若云止水
若云止水

mybatis02 CRUD

CRUD代表四个基本功能：创建（Create）、检索（Retrieve）、更新（Update）和删除（Delete）。它们是大多数应用程序所需要的最基本的持久化操作。

- 创建（Create）: 这是指创建或添加新的条目。
- 检索（Retrieve）: 这是指读取或查看已有的条目。
- 更新（Update）: 这是指更新或修改已有的条目。
- 删除（Delete）: 这是指删除已有的条目。

pom.xml



    4.0.0

    com.wsd
    testMyBatis2
    1.0-SNAPSHOT
    jar

    
        
        
            org.mybatis
            mybatis
            3.5.10
        

        
        
            mysql
            mysql-connector-java
            8.0.30
        

        
        
            junit
            junit
            4.13.2
            test
        
        
        
        
            ch.qos.logback
            logback-classic
            1.2.11
            test
        
    



    
        
            
                org.apache.maven.plugins
                maven-compiler-plugin
                3.1
                
                    17
                    17

mybatis-config.xml

CarMapper.xml




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,'102','霸图',50.30,'2024-11-05','新能源')

logback.xml




    
    
        
            
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
        
    
    
    
        
            
            ${LOG_HOME}/TestWeb.log.%d{yyyy-MM-dd}.log
            
            30
        
        
            
            %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n
        
        
        
            100MB

 

获取Sqlsession的工具类： 

package com.wsd;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

/**
 * @program: spring_learn
 * @description: Utility class for mybatis
 * @author: Mr.Wang
 * @create: 2023-06-17 17:38
 **/
public class SqlSessionUtil {

    private SqlSessionUtil(){}

    private static SqlSessionFactory sqlSessionFactory;

    /**
     * 类加载时初始化sqlSessionFactory对象
     */
    static {
        try {
            SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
            sqlSessionFactory = sqlSessionFactoryBuilder.build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 每调用一次openSession()可获取一个新的会话。
     *
     * @return 新的会话对象
     */
    public static SqlSession openSession() {
        return sqlSessionFactory.openSession();
    }
}

test:

package com.wsd;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testInsert(){

        // 准备数据
        Map map = new HashMap<>();
        map.put("k1", "103");
        map.put("k2", "虚空");
        map.put("k3", 50.3);
        map.put("k4", "2021-01-07");
        map.put("k5", "新能源");

        SqlSession sqlSession = SqlSessionUtil.openSession();

        /*
        * 执行sql语句
        * parameter1 insertCar CarMapper.xml insert标签的id,
        * parameter2
        * */
        int count = sqlSession.insert("insertCar",);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();

    }
}

CarMapper.xml




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{k1},#{k2},#{k3},#{k4},#{k5})

mybatis将 sql 中 #{k1} 中的值k1作为 map 的 key ,从而获取k1对应的value 103,将 #{k1} 替换为 103，形成最终的sql 语句 

test result:

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=62981 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testInsert
2023-06-17 21:13:05.633 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-17 21:13:05.634 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:13:05.634 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:13:05.634 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:13:05.634 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:13:05.696 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-17 21:13:05.933 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 937744315.
2023-06-17 21:13:05.933 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:13:05.933 [main] DEBUG car.insertCar - ==>  Preparing: insert into t_car (id,car_num,brand,guide_price,produce_time,car_type) values (null,?,?,?,?,?)
2023-06-17 21:13:05.963 [main] DEBUG car.insertCar - ==> Parameters: 103(String), 虚空(String), 50.3(Double), 2021-01-07(String), 新能源(String)
2023-06-17 21:13:05.979 [main] DEBUG car.insertCar - <==    Updates: 1
1
2023-06-17 21:13:05.979 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:13:05.979 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:13:05.979 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:13:05.979 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 937744315 to pool.

Process finished with exit code 0
 

 

 mybatis02 CRUD_第1张图片

 

修改：

CarMapper.xml:




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})

test:

package com.wsd;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testInsert(){

        // 准备数据
        Map map = new HashMap<>();
        map.put("carNum", "104");
        map.put("brand", "301");
        map.put("guidePrice", 30.6);
        map.put("produceTime", "2021-03-06");
        map.put("carType", "新能源");

        SqlSession sqlSession = SqlSessionUtil.openSession();

        /*
        * 执行sql语句
        * parameter1 insertCar CarMapper.xml insert标签的id,
        * parameter2 map sql语句需要的数据
        * */
        int count = sqlSession.insert("insertCar",map);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();

    }
}

test result :

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=63121 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testInsert
2023-06-17 21:21:15.876 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-17 21:21:15.892 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:21:15.892 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:21:15.892 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:21:15.892 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 21:21:15.954 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-17 21:21:16.158 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 937744315.
2023-06-17 21:21:16.158 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:21:16.158 [main] DEBUG car.insertCar - ==>  Preparing: insert into t_car (id,car_num,brand,guide_price,produce_time,car_type) values (null,?,?,?,?,?)
2023-06-17 21:21:16.190 [main] DEBUG car.insertCar - ==> Parameters: 104(String), 301(String), 30.6(Double), 2021-03-06(String), 新能源(String)
2023-06-17 21:21:16.212 [main] DEBUG car.insertCar - <==    Updates: 1
1
2023-06-17 21:21:16.212 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:21:16.212 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:21:16.212 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-17 21:21:16.212 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 937744315 to pool.

Process finished with exit code 0
 

mybatis02 CRUD_第2张图片 

 

使用 pojo（简单普通的java对象）封装sql 需要的data

package com.wsd.pojo;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 21:53
 **/
public class Car {

    private Long id;
    private String carNum;
    private String brand;
    private Double guidePrice;
    private String produceTime;
    private String carType;

    @Override
    public String toString() {
        return "Car{" +
                "id=" + id +
                ", carNum='" + carNum + '\'' +
                ", brand='" + brand + '\'' +
                ", guidePrice=" + guidePrice +
                ", produceTime='" + produceTime + '\'' +
                ", carType='" + carType + '\'' +
                '}';
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getCarNum() {
        return carNum;
    }

    public void setCarNum(String carNum) {
        this.carNum = carNum;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public Double getGuidePrice() {
        return guidePrice;
    }

    public void setGuidePrice(Double guidePrice) {
        this.guidePrice = guidePrice;
    }

    public String getProduceTime() {
        return produceTime;
    }

    public void setProduceTime(String produceTime) {
        this.produceTime = produceTime;
    }

    public String getCarType() {
        return carType;
    }

    public void setCarType(String carType) {
        this.carType = carType;
    }
}

CarMapper.xml :




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})

 #{carNum} carNum 是 Car 的属性 carNum 

mybatis 根据  #{carNum} 中的 carNum 推断其getter 方法 为getCarNum(),

(推断: get + carNum首字母大写  )

然后调用 Car 的 getCarNum() 获取属性的值value，并以value 替代 #{carNum} 的位置

test:

package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testInsertCarByPOJO(){
        // 创建POJO，封装数据
        Car car = new Car();
        car.setCarNum("104");
        car.setBrand("百花");
        car.setGuidePrice(36.23);
        car.setProduceTime("2020-02-22");
        car.setCarType("新能源");
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL，传数据
        int count = sqlSession.insert("insertCar", car);
        System.out.println("插入了几条记录" + count);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testInsert(){

        // 准备数据
        Map map = new HashMap<>();
        map.put("carNum", "104");
        map.put("brand", "301");
        map.put("guidePrice", 30.6);
        map.put("produceTime", "2021-03-06");
        map.put("carType", "新能源");

        SqlSession sqlSession = SqlSessionUtil.openSession();

        /*
        * 执行sql语句
        * parameter1 insertCar CarMapper.xml insert标签的id,
        * parameter2 map sql语句需要的数据
        * */
        int count = sqlSession.insert("insertCar",map);
        System.out.println(count);
        sqlSession.commit();
        sqlSession.close();

    }
}

testInsertCarByPOJO result:

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=63996 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testInsertCarByPOJO
2023-06-17 22:07:27.838 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-17 22:07:27.846 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 22:07:27.846 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 22:07:27.846 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 22:07:27.846 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-17 22:07:27.908 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-17 22:07:28.112 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 1870209957.
2023-06-17 22:07:28.112 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-17 22:07:28.112 [main] DEBUG car.insertCar - ==>  Preparing: insert into t_car (id,car_num,brand,guide_price,produce_time,car_type) values (null,?,?,?,?,?)
2023-06-17 22:07:28.144 [main] DEBUG car.insertCar - ==> Parameters: 104(String), 百花(String), 36.23(Double), 2020-02-22(String), 新能源(String)
2023-06-17 22:07:28.176 [main] DEBUG car.insertCar - <==    Updates: 1
插入了几条记录1
2023-06-17 22:07:28.176 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-17 22:07:28.176 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-17 22:07:28.176 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-17 22:07:28.176 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 1870209957 to pool.

Process finished with exit code 0
 

table:

mybatis02 CRUD_第3张图片 

 

delete

CarMapper.xml:




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}

 test:

package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testDeleteByCarNum(){
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        int count = sqlSession.delete("deleteByCarNum", "102");
        System.out.println("删除了几条记录：" + count);
        sqlSession.commit();
        sqlSession.close();
    }
    
}

只有一个占位符 #{}，那么#{} 中的内容没有要求，随意
 delete from t_car where car_num = #{carNum} 
int count = sqlSession.delete("deleteByCarNum", "102");

test result:

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=50561 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testDeleteByCarNum
2023-06-18 09:20:35.649 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-18 09:20:35.664 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 09:20:35.664 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 09:20:35.664 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 09:20:35.664 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 09:20:35.789 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-18 09:20:36.166 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 937744315.
2023-06-18 09:20:36.166 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-18 09:20:36.182 [main] DEBUG car.deleteByCarNum - ==>  Preparing: delete from t_car where car_num = ?
2023-06-18 09:20:36.213 [main] DEBUG car.deleteByCarNum - ==> Parameters: 102(String)
2023-06-18 09:20:36.229 [main] DEBUG car.deleteByCarNum - <==    Updates: 7
删除了几条记录：7
2023-06-18 09:20:36.229 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-18 09:20:36.229 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-18 09:20:36.244 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@37e4d7bb]
2023-06-18 09:20:36.244 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 937744315 to pool.

Process finished with exit code 0
 

table data: 

 mybatis02 CRUD_第4张图片

 

update:

CarMapper.xml




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}
    

    
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}

test:

package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testUpdateCarById(){
        // 准备数据
        Car car = new Car();
        car.setId(172L);
        car.setCarNum("102");
        car.setBrand("微草");
        car.setGuidePrice(30.23);
        car.setProduceTime("2022-04-13");
        car.setCarType("新能源");
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        int count = sqlSession.update("updateCarById", car);
        System.out.println("更新了几条记录：" + count);
        sqlSession.commit();
        sqlSession.close();
    }
}

result:

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=52073 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testUpdateCarById
2023-06-18 10:13:59.845 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-18 10:13:59.865 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:13:59.865 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:13:59.865 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:13:59.865 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:13:59.946 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-18 10:14:00.277 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 1870209957.
2023-06-18 10:14:00.277 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-18 10:14:00.277 [main] DEBUG car.updateCarById - ==>  Preparing: update t_car set car_num = ?, brand = ?, guide_price = ?, produce_time = ?, car_type = ? where id = ?
2023-06-18 10:14:00.325 [main] DEBUG car.updateCarById - ==> Parameters: 102(String), 微草(String), 30.23(Double), 2022-04-13(String), 新能源(String), 172(Long)
2023-06-18 10:14:00.348 [main] DEBUG car.updateCarById - <==    Updates: 1
更新了几条记录：1
2023-06-18 10:14:00.366 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-18 10:14:00.366 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-18 10:14:00.366 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6f7923a5]
2023-06-18 10:14:00.366 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 1870209957 to pool.

Process finished with exit code 0
 

table data : 

mybatis02 CRUD_第5张图片

selectOne :

 CarMapper.xml




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}
    

    
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}

 

resultType="com.wsd.pojo.Car"  用com.wsd.pojo.Car 类型 来封装查询的结果

创建一个Car对象，将查询结果的字段赋值给对象相对应的属性

 

test :

package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testSelectCarById(){
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        //selectOne 只会返回一条查询结果
        Object car = sqlSession.selectOne("selectCarById", 172);
        System.out.println(car);
        sqlSession.commit();
        sqlSession.close();
    }

}

result :

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=52438 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testSelectCarById
2023-06-18 10:34:15.185 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-18 10:34:15.192 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:34:15.192 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:34:15.200 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:34:15.200 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:34:15.250 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-18 10:34:15.430 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 157168588.
2023-06-18 10:34:15.430 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:34:15.440 [main] DEBUG car.selectCarById - ==>  Preparing: select * from t_car where id = ?
2023-06-18 10:34:15.476 [main] DEBUG car.selectCarById - ==> Parameters: 172(Integer)
2023-06-18 10:34:15.511 [main] DEBUG car.selectCarById - <==      Total: 1
Car{id=172, carNum='null', brand='微草', guidePrice=null, produceTime='null', carType='null'}
2023-06-18 10:34:15.530 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:34:15.530 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:34:15.530 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 157168588 to pool.

Process finished with exit code 0
 

 carNum='null'  是因为 Car 的属性carNum 与 列名 car_num 不一样，所以没能成功赋值

修改：

CarMapper.xml :




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}
    

    
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}

select id,car_num as carNum,brand,guide_price as guidePrice,produce_time as produceTime,car_type as carType
from t_car
where id = #{id}

car_num as carNum 通过其别名来使查询结果的列名和Car 的属性可以相对应

 

 retest result :

"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=52894 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testSelectCarById
2023-06-18 10:53:03.996 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
2023-06-18 10:53:03.996 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:53:03.996 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:53:03.996 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:53:03.996 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
2023-06-18 10:53:04.059 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
2023-06-18 10:53:04.232 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 157168588.
2023-06-18 10:53:04.232 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:53:04.232 [main] DEBUG car.selectCarById - ==>  Preparing: select id,car_num as carNum,brand,guide_price as guidePrice,produce_time as produceTime,car_type as carType from t_car where id = ?
2023-06-18 10:53:04.264 [main] DEBUG car.selectCarById - ==> Parameters: 172(Integer)
2023-06-18 10:53:04.296 [main] DEBUG car.selectCarById - <==      Total: 1
Car{id=172, carNum='102', brand='微草', guidePrice=30.23, produceTime='2022-04-13', carType='新能源'}
2023-06-18 10:53:04.311 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:53:04.311 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 10:53:04.311 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 157168588 to pool.

Process finished with exit code 0
 

selectList        :

CarMapper.xml




    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}
    

    
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}

test:

package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testSelectCarAll(){
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        List cars = sqlSession.selectList("selectCarAll");
        sqlSession.commit();
        sqlSession.close();
        // 输出结果
        cars.forEach(car -> System.out.println(car));
        
    }
}


result :




"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=59232 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testSelectCarAll
 2023-06-18 12:08:02.268 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
 2023-06-18 12:08:02.281 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:08:02.281 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:08:02.281 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:08:02.281 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:08:02.331 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
 2023-06-18 12:08:02.498 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 157168588.
 2023-06-18 12:08:02.498 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
2023-06-18 12:08:02.501 [main] DEBUG car.selectCarAll - ==>  Preparing: select id, car_num as carNum, brand, guide_price as guidePrice, produce_time as produceTime, car_type as carType from t_car
 2023-06-18 12:08:02.531 [main] DEBUG car.selectCarAll - ==> Parameters: 
 2023-06-18 12:08:02.565 [main] DEBUG car.selectCarAll - <==      Total: 10
 2023-06-18 12:08:02.567 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
 2023-06-18 12:08:02.568 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@95e33cc]
 2023-06-18 12:08:02.568 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 157168588 to pool.
 Car{id=165, carNum='6666', brand='丰田霸道', guidePrice=32.0, produceTime='2020-11-11', carType='燃油车'}
 Car{id=166, carNum='1202', brand='大众速腾', guidePrice=30.0, produceTime='2020-11-11', carType='燃油车'}
 Car{id=167, carNum='1203', brand='奔驰GLC', guidePrice=5.0, produceTime='2010-12-03', carType='燃油车'}
 Car{id=168, carNum='1204', brand='奥迪Q7', guidePrice=3.0, produceTime='2009-10-11', carType='燃油车'}
 Car{id=169, carNum='1205', brand='朗逸', guidePrice=4.0, produceTime='2001-10-11', carType='新能源'}
 Car{id=171, carNum='1207', brand='奥迪A6', guidePrice=30.0, produceTime='2000-01-02', carType='燃油车'}
 Car{id=172, carNum='102', brand='微草', guidePrice=30.23, produceTime='2022-04-13', carType='新能源'}
 Car{id=181, carNum='103', brand='虚空', guidePrice=50.3, produceTime='2021-01-07', carType='新能源'}
 Car{id=182, carNum='104', brand='301', guidePrice=30.6, produceTime='2021-03-06', carType='新能源'}
 Car{id=183, carNum='104', brand='百花', guidePrice=36.23, produceTime='2020-02-22', carType='新能源'}


Process finished with exit code 0
  


    




mybatis02 CRUD_第6张图片 


 


namespace:


mybatis-config.xml :



        

    


    
        
        
            
            
            
            
        
    


    
    






有2个mapper文件




CarMapper.xml :





    
    
        insert into t_car
            (id,car_num,brand,guide_price,produce_time,car_type)
        values
            (null,#{carNum},#{brand},#{guidePrice},#{produceTime},#{carType})
    

    
        delete from t_car where car_num = #{carNum}
    

    
        update t_car set
            car_num = #{carNum},
            brand = #{brand},
            guide_price = #{guidePrice},
            produce_time = #{produceTime},
            car_type = #{carType}
        where id = #{id}
    

    

    
    



 CarMapper2.xml :





    
    



test :


package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testNamespace(){
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        List cars = sqlSession.selectList("selectCarAll");
        sqlSession.commit();
        sqlSession.close();
        // 输出结果
        cars.forEach(car -> System.out.println(car));
    }

}


result :




"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=59606 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testNamespace
 2023-06-18 12:23:21.435 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
 2023-06-18 12:23:21.451 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:23:21.451 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:23:21.451 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:23:21.451 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.


org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.IllegalArgumentException: selectCarAll is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)
 ### Cause: java.lang.IllegalArgumentException: selectCarAll is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)


    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
     at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:153)
     at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:145)
     at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
     at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:135)
     at com.wsd.TestCarMapper.testNamespace(TestCarMapper.java:24)
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     at java.base/java.lang.reflect.Method.invoke(Method.java:568)
     at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
     at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
     at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
     at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
     at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
     at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
     at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
     at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
     at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
     at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
     at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
     at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
     at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
     at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
     at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
     at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
     at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
     at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
     at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
     at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
     at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
     at java.base/java.lang.reflect.Method.invoke(Method.java:568)
     at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:131)
 Caused by: java.lang.IllegalArgumentException: selectCarAll is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)
     at org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:1066)
     at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:853)
     at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:846)
     at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
     ... 34 more



 Process finished with exit code -1
  






selectCarAll is ambiguous in Mapped Statements collection (try using the full name including the namespace, or rename one of the entries)


selectCarAll在映射语句集合中是不明确的(尝试使用包含名称空间的全名，或者重命名其中一个条目


2个Mapper.xml 文件中都有 selectAll,不清楚具体使用哪一个






修改：


package com.wsd;

import com.wsd.pojo.Car;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @program: spring_learn
 * @description:
 * @author: Mr.Wang
 * @create: 2023-06-17 20:53
 **/
public class TestCarMapper {

    @Test
    public void testNamespace(){
        // 获取SqlSession对象
        SqlSession sqlSession = SqlSessionUtil.openSession();
        // 执行SQL语句
        List cars = sqlSession.selectList("car2.selectCarAll");
        sqlSession.commit();
        sqlSession.close();
        // 输出结果
        cars.forEach(car -> System.out.println(car));
    }

}


retest result :




"C:\Program Files\Java\jdk-17\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 -Didea.launcher.port=59803 "-Didea.launcher.bin.path=C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\lib\idea_rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit-rt.jar;C:\Minecloud\IDEA_2019\IntelliJ IDEA 2019.1\plugins\junit\lib\junit5-rt.jar;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\test-classes;C:\Minecloud\IDEA_workspace\spring_learn\testMyBatis2\target\classes;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\mybatis\mybatis\3.5.10\mybatis-3.5.10.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\mysql\mysql-connector-java\8.0.30\mysql-connector-java-8.0.30.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\com\google\protobuf\protobuf-java\3.19.4\protobuf-java-3.19.4.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\junit\junit\4.13.2\junit-4.13.2.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-classic\1.2.11\logback-classic-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\ch\qos\logback\logback-core\1.2.11\logback-core-1.2.11.jar;C:\Minecloud\maven_3.9\apache-maven-3.9.0\repo\org\slf4j\slf4j-api\1.7.32\slf4j-api-1.7.32.jar" com.intellij.rt.execution.application.AppMainV2 com.intellij.rt.execution.junit.JUnitStarter -ideVersion5 -junit4 com.wsd.TestCarMapper,testNamespace
 2023-06-18 12:31:09.418 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.
 2023-06-18 12:31:09.442 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:31:09.442 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:31:09.442 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:31:09.442 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
 2023-06-18 12:31:09.512 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
 2023-06-18 12:31:09.764 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 1939022383.
 2023-06-18 12:31:09.764 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7393222f]
2023-06-18 12:31:09.779 [main] DEBUG car2.selectCarAll - ==>  Preparing: select brand, guide_price as guidePrice, produce_time as produceTime, car_type as carType from t_car
 2023-06-18 12:31:09.842 [main] DEBUG car2.selectCarAll - ==> Parameters: 
 2023-06-18 12:31:09.943 [main] DEBUG car2.selectCarAll - <==      Total: 10
 2023-06-18 12:31:09.943 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7393222f]
 2023-06-18 12:31:09.943 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@7393222f]
 2023-06-18 12:31:09.943 [main] DEBUG o.apache.ibatis.datasource.pooled.PooledDataSource - Returned connection 1939022383 to pool.
 Car{id=null, carNum='null', brand='丰田霸道', guidePrice=32.0, produceTime='2020-11-11', carType='燃油车'}
 Car{id=null, carNum='null', brand='大众速腾', guidePrice=30.0, produceTime='2020-11-11', carType='燃油车'}
 Car{id=null, carNum='null', brand='奔驰GLC', guidePrice=5.0, produceTime='2010-12-03', carType='燃油车'}
 Car{id=null, carNum='null', brand='奥迪Q7', guidePrice=3.0, produceTime='2009-10-11', carType='燃油车'}
 Car{id=null, carNum='null', brand='朗逸', guidePrice=4.0, produceTime='2001-10-11', carType='新能源'}
 Car{id=null, carNum='null', brand='奥迪A6', guidePrice=30.0, produceTime='2000-01-02', carType='燃油车'}
 Car{id=null, carNum='null', brand='微草', guidePrice=30.23, produceTime='2022-04-13', carType='新能源'}
 Car{id=null, carNum='null', brand='虚空', guidePrice=50.3, produceTime='2021-01-07', carType='新能源'}
 Car{id=null, carNum='null', brand='301', guidePrice=30.6, produceTime='2021-03-06', carType='新能源'}
 Car{id=null, carNum='null', brand='百花', guidePrice=36.23, produceTime='2020-02-22', carType='新能源'}


Process finished with exit code 0
  






2个不同 namespace 中 可以使用相同的 id,加上 namespace 作为前缀就可以将 2个相同的 id 区分出来





























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    华为OD2023（B卷）机试题库全覆盖，刷题指南点这里WeAreATeam时间限制：1秒|内存限制：32768K|语言限制：不限题目描述：总共有n个人在机房，每个人有一个标号（1<=标号<=n），他们分成了多个团队，需要你根据收到的m条消息判定指定的两个人是否在一个团队中，具体的：1、消息构成为：abc，整数a、b分别代
    

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  • 关于城市旅游的HTML网页设计——(旅游风景云南 5页)HTML+CSS+JavaScript
二挡起步
web前端期末大作业javascripthtmlcss旅游风景

    ⛵源码获取文末联系✈Web前端开发技术描述网页设计题材，DIV+CSS布局制作,HTML+CSS网页设计期末课程大作业|游景点介绍|旅游风景区|家乡介绍|等网站的设计与制作|HTML期末大学生网页设计作业，Web大学生网页HTML：结构CSS：样式在操作方面上运用了html5和css3，采用了div+css结构、表单、超链接、浮动、绝对定位、相对定位、字体样式、引用视频等基础知识JavaScrip
    

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  • HTML网页设计制作大作业（div+css） 云南我的家乡旅游景点 带文字滚动
二挡起步
web前端期末大作业web设计网页规划与设计htmlcssjavascriptdreamweaver前端

    Web前端开发技术描述网页设计题材，DIV+CSS布局制作,HTML+CSS网页设计期末课程大作业游景点介绍|旅游风景区|家乡介绍|等网站的设计与制作HTML期末大学生网页设计作业HTML：结构CSS：样式在操作方面上运用了html5和css3，采用了div+css结构、表单、超链接、浮动、绝对定位、相对定位、字体样式、引用视频等基础知识JavaScript：做与用户的交互行为文章目录前端学习路线
    

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  • node.js学习
小猿L
node.jsnode.js学习vim

    node.js学习实操及笔记温故node.js，node.js学习实操过程及笔记~node.js学习视频node.js官网node.js中文网实操笔记githubcsdn笔记为什么学node.js可以让别人访问我们编写的网页为后续的框架学习打下基础，三大框架vuereactangular离不开node.jsnode.js是什么官网：node.js是一个开源的、跨平台的运行JavaScript的运行
    

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  • insert into select 主键自增_mybatis拦截器实现主键自动生成
weixin_39521651
insertintoselect主键自增mybatisdelete返回值mybatisinsert返回主键mybatisinsert返回对象mybatisplusinsert返回主键mybatisplus插入生成id

    前言前阵子和朋友聊天，他说他们项目有个需求，要实现主键自动生成，不想每次新增的时候，都手动设置主键。于是我就问他，那你们数据库表设置主键自动递增不就得了。他的回答是他们项目目前的id都是采用雪花算法来生成，因此为了项目稳定性，不会切换id的生成方式。朋友问我有没有什么实现思路，他们公司的orm框架是mybatis，我就建议他说，不然让你老大把mybatis切换成mybatis-plus。mybat
    

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  • Java 重写(Override)与重载(Overload)
叨唧唧的

    Java重写(Override)与重载(Overload)重写(Override)重写是子类对父类的允许访问的方法的实现过程进行重新编写,返回值和形参都不能改变。即外壳不变，核心重写！重写的好处在于子类可以根据需要，定义特定于自己的行为。也就是说子类能够根据需要实现父类的方法。重写方法不能抛出新的检查异常或者比被重写方法申明更加宽泛的异常。例如：父类的一个方法申明了一个检查异常IOExceptio
    

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  • 简单了解 JVM
记得开心一点啊
jvm

    目录♫什么是JVM♫JVM的运行流程♫JVM运行时数据区♪虚拟机栈♪本地方法栈♪堆♪程序计数器♪方法区/元数据区♫类加载的过程♫双亲委派模型♫垃圾回收机制♫什么是JVMJVM是JavaVirtualMachine的简称，意为Java虚拟机。虚拟机是指通过软件模拟的具有完整硬件功能的、运行在一个完全隔离的环境中的完整计算机系统（如：JVM、VMwave、VirtualBox）。JVM和其他两个虚拟机
    

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  • 1分钟解决 -bash: mvn: command not found，在Centos 7中安装Maven
Energet!c
开发语言

    1分钟解决-bash:mvn:commandnotfound，在Centos7中安装Maven检查Java环境1下载Maven2解压Maven3配置环境变量4验证安装5常见问题与注意事项6总结检查Java环境Maven依赖Java环境，请确保系统已经安装了Java并配置了环境变量。可以通过以下命令检查：java-version如果未安装，请先安装Java。1下载Maven从官网下载：前往Apach
    

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  • Java企业面试题3
马龙强_
java

    1.break和continue的作用(智*图)break：用于完全退出一个循环（如for,while）或一个switch语句。当在循环体内遇到break语句时，程序会立即跳出当前循环体，继续执行循环之后的代码。continue：用于跳过当前循环体中剩余的部分，并开始下一次循环。如果是在for循环中使用continue，则会直接进行条件判断以决定是否执行下一轮循环。2.if分支语句和switch分
    

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  • JVM、JRE和 JDK：理解Java开发的三大核心组件
Y雨何时停T
Javajava

    Java是一门跨平台的编程语言，它的成功离不开背后强大的运行环境与开发工具的支持。在Java的生态中，JVM（Java虚拟机）、JRE（Java运行时环境）和JDK（Java开发工具包）是三个至关重要的核心组件。本文将探讨JVM、JDK和JRE的区别，帮助你更好地理解Java的运行机制。1.JVM：Java虚拟机（JavaVirtualMachine）什么是JVM？JVM，即Java虚拟机，是Ja
    

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  • Java面试题精选：消息队列(二)
芒果不是芒
Java面试题精选javakafka

    一、Kafka的特性1.消息持久化：消息存储在磁盘，所以消息不会丢失2.高吞吐量：可以轻松实现单机百万级别的并发3.扩展性：扩展性强，还是动态扩展4.多客户端支持：支持多种语言（Java、C、C++、GO、）5.KafkaStreams（一个天生的流处理）:在双十一或者销售大屏就会用到这种流处理。使用KafkaStreams可以快速的把销售额统计出来6.安全机制：Kafka进行生产或者消费的时候会
    

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  • 白骑士的Java教学基础篇 2.5 控制流语句
白骑士所长
Java教学java开发语言

    欢迎继续学习Java编程的基础篇！在前面的章节中，我们了解了Java的变量、数据类型和运算符。接下来，我们将探讨Java中的控制流语句。控制流语句用于控制程序的执行顺序，使我们能够根据特定条件执行不同的代码块，或重复执行某段代码。这是编写复杂程序的基础。通过学习这一节内容，你将掌握如何使用条件语句和循环语句来编写更加灵活和高效的代码。条件语句条件语句用于根据条件的真假来执行不同的代码块。if语句‘
    

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  • python语法——三目运算符
HappyRocking
pythonpython三目运算符

    在java中，有三目运算符，如：intc=(a>b)?a:b表示c取两者中的较大值。但是在python，不能直接这样使用，估计是因为冒号在python有分行的关键作用。那么在python中，如何实现类似功能呢？可以使用ifelse语句，也是一行可以完成，格式为：aifbelsec表示如果b为True，则表达式等于a，否则等于c。如：c=(aif(a>b)elseb)同样是完成了取最大值的功能。
    

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  • ArrayList 源码解析
程序猿进阶
Java基础ArrayListListjava面试性能优化架构设计idea

    ArrayList是Java集合框架中的一个动态数组实现，提供了可变大小的数组功能。它继承自AbstractList并实现了List接口，是顺序容器，即元素存放的数据与放进去的顺序相同，允许放入null元素，底层通过数组实现。除该类未实现同步外，其余跟Vector大致相同。每个ArrayList都有一个容量capacity，表示底层数组的实际大小，容器内存储元素的个数不能多于当前容量。当向容器中添
    

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  • Java爬虫框架（一）--架构设计
狼图腾-狼之传说
java框架java任务html解析器存储电子商务

    一、架构图那里搜网络爬虫框架主要针对电子商务网站进行数据爬取，分析，存储，索引。爬虫：爬虫负责爬取，解析，处理电子商务网站的网页的内容数据库：存储商品信息索引：商品的全文搜索索引Task队列：需要爬取的网页列表Visited表：已经爬取过的网页列表爬虫监控平台：web平台可以启动，停止爬虫，管理爬虫，task队列，visited表。二、爬虫1.流程1)Scheduler启动爬虫器，TaskMast
    

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  • Java：爬虫框架
dingcho
Javajava爬虫

    一、ApacheNutch2【参考地址】Nutch是一个开源Java实现的搜索引擎。它提供了我们运行自己的搜索引擎所需的全部工具。包括全文搜索和Web爬虫。Nutch致力于让每个人能很容易,同时花费很少就可以配置世界一流的Web搜索引擎.为了完成这一宏伟的目标,Nutch必须能够做到:每个月取几十亿网页为这些网页维护一个索引对索引文件进行每秒上千次的搜索提供高质量的搜索结果简单来说Nutch支持分
    

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  • python怎么将png转为tif_png转tif
weixin_39977276

    发国外的文章要求图片是tif，cmyk色彩空间的。大小尺寸还有要求。比如网上大神多，找到了一段代码，感谢！https://www.jianshu.com/p/ec2af4311f56https://github.com/KevinZc007/image2Tifimportjava.awt.image.BufferedImage;importjava.io.File;importjava.io.Fi
    

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  • JavaScript 中，深拷贝（Deep Copy）和浅拷贝（Shallow Copy）
跳房子的前端
前端面试javascript开发语言ecmascript

    在JavaScript中，深拷贝（DeepCopy）和浅拷贝（ShallowCopy）是用于复制对象或数组的两种不同方法。了解它们的区别和应用场景对于避免潜在的bugs和高效地处理数据非常重要。以下是对深拷贝和浅拷贝的详细解释，包括它们的概念、用途、优缺点以及实现方式。1.浅拷贝（ShallowCopy）概念定义：浅拷贝是指创建一个新的对象或数组，其中包含了原对象或数组的基本数据类型的值和对引用数
    

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  • JAVA·一个简单的登录窗口
MortalTom
java开发语言学习

    文章目录概要整体架构流程技术名词解释技术细节资源概要JavaSwing是Java基础类库的一部分，主要用于开发图形用户界面（GUI）程序整体架构流程新建项目，导入sql.jar包（链接放在了文末），编译项目并运行技术名词解释一、特点丰富的组件提供了多种可视化组件，如按钮（JButton）、文本框（JTextField）、标签（JLabel）、下拉列表（JComboBox）等，可以满足不同的界面设计
    

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  • WebMagic：强大的Java爬虫框架解析与实战
Aaron_945
Javajava爬虫开发语言

    文章目录引言官网链接WebMagic原理概述基础使用1.添加依赖2.编写PageProcessor高级使用1.自定义Pipeline2.分布式抓取优点结论引言在大数据时代，网络爬虫作为数据收集的重要工具，扮演着不可或缺的角色。Java作为一门广泛使用的编程语言，在爬虫开发领域也有其独特的优势。WebMagic是一个开源的Java爬虫框架，它提供了简单灵活的API，支持多线程、分布式抓取，以及丰富的
    

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  • 博客网站制作教程
2401_85194651
javamaven

    首先就是技术框架：后端：Java+SpringBoot数据库：MySQL前端：Vue.js数据库连接：JPA(JavaPersistenceAPI)1.项目结构blog-app/├──backend/│├──src/main/java/com/example/blogapp/││├──BlogApplication.java││├──config/│││└──DatabaseConfig.java
    

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  • 00. 这里整理了最全的爬虫框架（Java + Python）
有一只柴犬
爬虫系列爬虫javapython

    目录1、前言2、什么是网络爬虫3、常见的爬虫框架3.1、java框架3.1.1、WebMagic3.1.2、Jsoup3.1.3、HttpClient3.1.4、Crawler4j3.1.5、HtmlUnit3.1.6、Selenium3.2、Python框架3.2.1、Scrapy3.2.2、BeautifulSoup+Requests3.2.3、Selenium3.2.4、PyQuery3.2
    

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  • JAVA学习笔记之23种设计模式学习
victorfreedom
Java技术设计模式androidjava常用设计模式

    博主最近买了《设计模式》这本书来学习，无奈这本书是以C++语言为基础进行说明，整个学习流程下来效率不是很高，虽然有的设计模式通俗易懂，但感觉还是没有充分的掌握了所有的设计模式。于是博主百度了一番，发现有大神写过了这方面的问题，于是博主迅速拿来学习。一、设计模式的分类总体来说设计模式分为三大类：创建型模式，共五种：工厂方法模式、抽象工厂模式、单例模式、建造者模式、原型模式。结构型模式，共七种：适配器
    

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  • JavaScript `Map` 和 `WeakMap`详细解释
跳房子的前端
JavaScript原生方法javascript前端开发语言

    在JavaScript中，Map和WeakMap都是用于存储键值对的数据结构，但它们有一些关键的不同之处。MapMap是一种可以存储任意类型的键值对的集合。它保持了键值对的插入顺序，并且可以通过键快速查找对应的值。Map提供了一些非常有用的方法和属性来操作这些数据对：set(key,value):将一个键值对添加到Map中。如果键已经存在，则更新其对应的值。get(key):获取指定键的值。如果键
    

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  • MyBatis 详解
阿贾克斯的黎明
javamybatis

    目录目录一、MyBatis是什么二、为什么使用MyBatis（一）灵活性高（二）性能优化（三）易于维护三、怎么用MyBatis（一）添加依赖（二）配置MyBatis（三）创建实体类和接口（四）使用MyBatis一、MyBatis是什么MyBatis是一个优秀的持久层框架，它支持自定义SQL、存储过程以及高级映射。MyBatis免除了几乎所有的JDBC代码以及设置参数和获取结果集的工作。它可以通过简
    

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  • 切换淘宝最新npm镜像源是
hai40587
npm前端node.js

    切换淘宝最新npm镜像源是一个相对简单的过程，但首先需要明确当前淘宝npm镜像源的状态和最新的镜像地址。由于网络环境和服务更新，镜像源的具体地址可能会发生变化，因此，我将基于当前可获取的信息，提供一个通用的切换步骤，并附上最新的镜像地址（截至回答时）。一、了解npm镜像源npm（NodePackageManager）是JavaScript的包管理器，用于安装、更新和管理项目依赖。由于npm官方仓库
    

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  • jquery实现的jsonp掉java后台
知了ing
javajsonpjquery

     什么是JSONP？
先说说JSONP是怎么产生的：
其实网上关于JSONP的讲解有很多，但却千篇一律，而且云里雾里，对于很多刚接触的人来讲理解起来有些困难，小可不才，试着用自己的方式来阐释一下这个问题，看看是否有帮助。
1、一个众所周知的问题，Ajax直接请求普通文件存在跨域无权限访问的问题，甭管你是静态页面、动态网页、web服务、WCF，只要是跨域请求，一律不准；
2、
    

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  • Struts2学习笔记
caoyong
struts2

    SSH : Spring + Struts2 + Hibernate
三层架构(表示层,业务逻辑层,数据访问层) MVC模式 (Model View Controller)
分层原则:单向依赖，接口耦合
1、Struts2  =  Struts  + Webwork
2、搭建struts2开发环境
   a>、到www.apac
    

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  • SpringMVC学习之后台往前台传值方法
满城风雨近重阳
springMVC

    springMVC控制器往前台传值的方法有以下几种：
1.ModelAndView
   通过往ModelAndView中存放viewName：目标地址和attribute参数来实现传参：
   
 ModelAndView mv=new ModelAndView();
 mv.setViewName="success
    

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  • WebService存在的必要性？
一炮送你回车库
webservice

    做Java的经常在选择Webservice框架上徘徊很久，Axis  Xfire Axis2 CXF ，他们只有一个功能，发布HTTP服务然后用XML做数据传输。
是的，他们就做了两个功能，发布一个http服务让客户端或者浏览器连接，接收xml参数并发送xml结果。
当在不同的平台间传输数据时，就需要一个都能解析的数据格式。
但是为什么要使用xml呢？不能使json或者其他通用数据
    

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  • js年份下拉框
3213213333332132
java web ee

    
<div id="divValue">test...</div>测试
//年份
<select id="year"></select>
<script type="text/javascript">
window.onload = 
    

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  • 简单链式调用的实现技术
归来朝歌
方法调用链式反应编程思想

    在编程中，我们可以经常遇到这样一种场景：一个实例不断调用它自身的方法，像一条链条一样进行调用
这样的调用你可能在Ajax中，在页面中添加标签：
$("<p>").append($("<span>").text(list[i].name)).appendTo("#result");
 
也可能在HQ
    

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  • JAVA调用.net 发布的webservice 接口
darkranger
webservice

     /**
* @Title: callInvoke
* @Description: TODO(调用接口公共方法)
* @param @param url 地址
* @param @param method 方法
* @param @param pama 参数
* @param @return
* @param @throws BusinessException 
    

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  • Javascript模糊查找 | 第一章 循环不能不重视。
aijuans
Way

     最近受我的朋友委托用js+HTML做一个像手册一样的程序，里面要有可展开的大纲，模糊查找等功能。我这个人说实在的懒，本来是不愿意的，但想起了父亲以前教我要给朋友搞好关系，再加上这也可以巩固自己的js技术，于是就开始开发这个程序，没想到却出了点小问题，我做的查找只能绝对查找。具体的js代码如下：
function search(){
var arr=new Array("my
    

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  • 狼和羊，该怎么抉择
atongyeye
工作

    狼和羊，该怎么抉择
在做一个链家的小项目，只有我和另外一个同事两个人负责，各负责一部分接口，我的接口写完，并全部测联调试通过。所以工作就剩下一下细枝末节的，工作就轻松很多。每天会帮另一个同事测试一些功能点，协助他完成一些业务型不强的工作。
今天早上到公司没多久，领导就在QQ上给我发信息，让我多协助同事测试，让我积极主动些，有点责任心等等，我听了这话，心里面立马凉半截，首先一个领导轻易说
    

    • 

  • 读取android系统的联系人拨号
百合不是茶
androidsqlite数据库内容提供者系统服务的使用

     
     联系人的姓名和号码是保存在不同的表中,不要一下子把号码查询来,我开始就是把姓名和电话同时查询出来的,导致系统非常的慢
 
关键代码:
 
 
1, 使用javabean操作存储读取到的数据
package com.example.bean;
/**
*
* @author Admini
    

    • 

  • ORACLE自定义异常
bijian1013
数据库自定义异常

    实例：
CREATE OR REPLACE PROCEDURE test_Exception
(
ParameterA IN varchar2,
ParameterB IN varchar2,
ErrorCode OUT varchar2 --返回值,错误编码
)
AS
/*以下是一些变量的定义*/
V1 NUMBER;
V2 nvarc
    

    • 

  • 查看端号使用情况
征客丶
windows

    一、查看端口
在windows命令行窗口下执行：
>netstat -aon|findstr "8080"
显示结果：
TCP     127.0.0.1:80         0.0.0.0:0    &
    

    • 

  • 【Spark二十】运行Spark Streaming的NetworkWordCount实例
bit1129
wordcount

    Spark Streaming简介
  NetworkWordCount代码
 
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with

    

    • 

  • Struts2 与 SpringMVC的比较
BlueSkator
struts2spring mvc

    1. 机制：spring mvc的入口是servlet，而struts2是filter，这样就导致了二者的机制不同。 2. 性能：spring会稍微比struts快。spring mvc是基于方法的设计，而sturts是基于类，每次发一次请求都会实例一个action，每个action都会被注入属性，而spring基于方法，粒度更细，但要小心把握像在servlet控制数据一样。spring
    

    • 

  • Hibernate在更新时，是可以不用session的update方法的(转帖）
BreakingBad
Hibernateupdate

    地址：http://blog.csdn.net/plpblue/article/details/9304459
public void synDevNameWithItil()
{Session session = null;Transaction tr = null;try{session = HibernateUtil.getSession();tr = session.beginTran
    

    • 

  • 读《研磨设计模式》-代码笔记-观察者模式
bylijinnan
java设计模式

    声明： 本文只为方便我个人查阅和理解，详细的分析以及源代码请移步 原作者的博客http://chjavach.iteye.com/
import java.util.ArrayList;
import java.util.List;
import java.util.Observable;
import java.util.Observer;
/**
* “观
    

    • 

  • 重置MySQL密码
chenhbc
mysql重置密码忘记密码

    如果你也像我这么健忘，把MySQL的密码搞忘记了，经过下面几个步骤就可以重置了（以Windows为例，Linux/Unix类似）：
1、关闭MySQL服务
2、打开CMD，进入MySQL安装目录的bin目录下，以跳过权限检查的方式启动MySQL
mysqld --skip-grant-tables
 3、新开一个CMD窗口，进入MySQL
mysql -uroot
 
    

    • 

  • 再谈系统论，控制论和信息论
comsci
设计模式生物能源企业应用领域模型

    
                           再谈系统论，控制论和信息论
    偶然看
    

    • 

  • oracle moving window size与 AWR retention period关系
daizj
oracle

    转自： http://tomszrp.itpub.net/post/11835/494147
晚上在做11gR1的一个awrrpt报告时,顺便想调整一下AWR snapshot的保留时间,结果遇到了ORA-13541这样的错误.下面是这个问题的发生和解决过程.
SQL> select * from v$version;
BANNER
-------------------
    

    • 

  • Python版B树
dieslrae
python

    话说以前的树都用java写的,最近发现python有点生疏了,于是用python写了个B树实现,B树在索引领域用得还是蛮多了,如果没记错mysql的默认索引好像就是B树...
首先是数据实体对象,很简单,只存放key,value
class Entity(object):
'''数据实体'''
def __init__(self,key,value)
    

    • 

  • C语言冒泡排序
dcj3sjt126com
算法

    代码示例：
# include <stdio.h>
//冒泡排序
void sort(int * a, int len)
{
int i, j, t;
for (i=0; i<len-1; i++)
{
for (j=0; j<len-1-i; j++)
{
if (a[j] > a[j+1]) // >表示升序 
    

    • 

  • 自定义导航栏样式
dcj3sjt126com
自定义

    -(void)setupAppAppearance
{
[[UILabel appearance] setFont:[UIFont fontWithName:@"FZLTHK—GBK1-0" size:20]];
[UIButton appearance].titleLabel.font =[UIFont fontWithName:@"FZLTH
    

    • 

  • 11.性能优化-优化-JVM参数总结
frank1234
jvm参数性能优化

    1.堆
-Xms --初始堆大小
-Xmx --最大堆大小
-Xmn --新生代大小
-Xss --线程栈大小
-XX:PermSize  --永久代初始大小
-XX:MaxPermSize  --永久代最大值
-XX:SurvivorRatio --新生代和suvivor比例,默认为8
-XX:TargetSurvivorRatio --survivor可使用
    

    • 

  • nginx日志分割 for linux
HarborChung
nginxlinux脚本

    nginx日志分割 for linux 默认情况下，nginx是不分割访问日志的，久而久之，网站的日志文件将会越来越大，占用空间不说，如果有问题要查看网站的日志的话，庞大的文件也将很难打开，于是便有了下面的脚本   使用方法，先将以下脚本保存为 cutlog.sh，放在/root 目录下，然后给予此脚本执行的权限
 
复制代码代码如下:
chmo
    

    • 

  • Spring4新特性——泛型限定式依赖注入
jinnianshilongnian
springspring4泛型式依赖注入

    Spring4新特性——泛型限定式依赖注入
Spring4新特性——核心容器的其他改进
Spring4新特性——Web开发的增强
Spring4新特性——集成Bean Validation 1.1(JSR-349)到SpringMVC 
Spring4新特性——Groovy Bean定义DSL
Spring4新特性——更好的Java泛型操作API 
Spring4新
    

    • 

  • centOS安装GCC和G++
liuxihope
centosgcc

    Centos支持yum安装，安装软件一般格式为yum install .......，注意安装时要先成为root用户。
按照这个思路，我想安装过程如下：
安装gcc：yum install gcc
安装g++： yum install g++
实际操作过程发现，只能有gcc安装成功，而g++安装失败，提示g++ command not found。上网查了一下，正确安装应该
    

    • 

  • 第13章 Ajax进阶（上）
onestopweb
Ajax

    index.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/
    

    • 

  • How to determine BusinessObjects service pack and fix pack
blueoxygen
BO

    http://bukhantsov.org/2011/08/how-to-determine-businessobjects-service-pack-and-fix-pack/
 
The table below is helpful. Reference
  BOE XI 3.x
12.0.0.
y BOE XI 3.0 12.0.
x.
y BO
    

    • 

  • Oracle里的自增字段设置
tomcat_oracle
oracle

    　大家都知道吧，这很坑，尤其是用惯了mysql里的自增字段设置，结果oracle里面没有的。oh，no 　　我用的是12c版本的，它有一个新特性，可以这样设置自增序列，在创建表是，把id设置为自增序列
create table t
(
id 　　 　　 number generated by default as identity (start with 1 increment b
    

    • 

  • Spring Security（01）——初体验
yang_winnie
springSecurity

    Spring Security（01）——初体验
    博客分类： spring Security
Spring Security入门安全认证
       首先我们为Spring Security专门建立一个Spring的配置文件，该文件就专门用来作为Spring Security的配置
    

    •