3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查

1、新建项目,如下图
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第1张图片

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第2张图片

2、导入mybatis所需要jar包,并加入依赖 add as library
mybatis需要jar包:mybatis-3.4.6.jar
mysql驱动jar包:mysql-connector-java-5.1.42.-bin.jar
日志记录jar包:log4j-1.2.14.jar
junit测试包:junit-4.12.jar和hamcrest-core-1.3.jar
所需jar包下载地址,包含整个项目代码
https://download.csdn.net/download/nba_linshuhao/10671396

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第3张图片

3、创建数据库,数据名字Student、表名字user
注意:字段id设置成自动递增
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第4张图片

4、IDEA配置Mysql数据源
idea右侧栏,选中DATABASE,然后点击+号—-DataSource-Mysql
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第5张图片

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第6张图片

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第7张图片

5、创建包,代码结构如下
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第8张图片

6、src下创建文件jdbc.properties
加上的useSSL=false原因是:
https://blog.csdn.net/u010429286/article/details/77750177

jdbc.properties代码如下:

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=UTF-8&useSSL=false
jdbc.username=root
jdbc.password=root

7、src下添加mybatis配置文件mybatis.cfg.xml,
创建mybatis.cfg.xml文件具体步骤看连接:
https://blog.csdn.net/nba_linshuhao/article/details/82735770

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第9张图片

mybatis.cfg.xml代码如下:(不是最终的,因为下面还需要添加内容)



<configuration>

    
    <properties resource="jdbc.properties">properties>

    
    <environments default="cybatis">
        <environment id="cybatis">
            
            <transactionManager type="JDBC" />

            
            
            
            
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            dataSource>
        environment>
    environments>

configuration>

8、log4j.properties代码如下:

### 设置Logger输出级别和输出目的地 ###
log4j.rootLogger=debug,stdout,logfile

### 把日志信息输出到控制台 ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
#log4j.appender.stdout.Target=System.err
log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout

### 把日志信息输出到文件:jbit.log ###
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=jbit.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %F %p %m%n

###显示SQL语句部分
log4j.logger.com.ibatis=DEBUG
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=DEBUG
log4j.logger.com.ibatis.common.jdbc.ScriptRunner=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

9、创建对应的实体对象文件: User.java
容易出错的点,忘记写无参构造方法,在接收查询结果时会用无参方法创建对象
详细解释见Userservice的方法selectUserById()中

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第10张图片

package com.cy.mybatis.beans;
import java.io.Serializable;
public class User implements Serializable {
    public  User(){}; 
    public  User(String username,String password,Double account){
        this.username=username;
        this.password=password;
        this.account=account;
    }
    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Double getAccount() {
        return account;
    }

    public void setAccount(Double account) {
        this.account = account;
    }

    private  Integer id;
    private  String username;
    private  String password;
    private Double account;


    public String toString() {
        return "User [id=" + id + ", username=" + username + ", password="
                + password + ", account=" + account + "]";
    }
}

10.创建方法接口UserMapper.java和定义操作user表的sql映射文件UserMapper.xml

3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第11张图片

01 接口UserMapper.java代码如下:

package com.cy.mybatis.mapper;
import com.cy.mybatis.beans.User;
import java.util.List;

public interface UserMapper {
    /**
     * 新增用戶
     * @param user
     * @return
     * @throws Exception
     */
    public int insertUser(User user) throws Exception;
    /**
     * 修改用戶
     * @param user
     * @param id
     * @return
     * @throws Exception
     */
    public int updateUser (User user,int id) throws Exception;
    /**
     * 刪除用戶
     * @param id
     * @return
     * @throws Exception
     */
    public int deleteUser(int id) throws Exception;
    /**
     * 根据id查询用户信息
     * @param id
     * @return
     * @throws Exception
     */
    public User selectUserById(int id) throws Exception;
    /**
     * 查询所有的用户信息
     * @return
     * @throws Exception
     */
    public List selectAllUser() throws Exception;
}

02、UserMapper.xml
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第12张图片

代码如下:



<mapper namespace="com.cy.mybatis.mapper.UserMapper">
    
    <resultMap id="userMap" type="User">
        <id property="id" column="id" javaType="java.lang.Integer">id>
        <result property="username" column="username" javaType="java.lang.String">result>
        <result property="password" column="password" javaType="java.lang.String">result>
        <result property="account" column="account" javaType="java.lang.Double">result>
    resultMap>
    
    
    
    


    <insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
        insert into user (username,password,account) values (#{username},#{password},#{account})
    insert>

    <update id="updateUser" >
        update user set username=#{username},password=#{password},account=#{account} where id=#{id}
    update>

    <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id}
    delete>

    <select id="selectUserById" parameterType="int" resultMap="userMap">
        select * from user where id=#{id}
    select>

    <select id="selectAllUser" resultMap="userMap">
        select * from user
    select>
mapper>

11、这时需要在mybatis.cfg.xml里注册UserMapper.xml文件
mybatis.cfg.xml的完整代码如下



<configuration>

    
    <properties resource="jdbc.properties">properties>

    
        <typeAliases >
             
             
             <package name="com.cy.mybatis.beans"/>
        typeAliases>


    
    <environments default="cybatis">
        <environment id="cybatis">
            
            <transactionManager type="JDBC" />

            
            
            
            
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            dataSource>
        environment>
    environments>

      
    <mappers>
        
        <mapper resource="com/cy/mybatis/mapper/UserMapper.xml"/>
        
        
    mappers>

configuration>

12、创建工具类文件DBTools.java
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第13张图片

代码如下:

package com.cy.mybatis.tools;

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

import java.io.Reader;

public class DBTools {
    public static SqlSessionFactory sessionFactory;

    static{
        try {
            //使用MyBatis提供的Resources类加载mybatis的配置文件
            Reader reader = Resources.getResourceAsReader("mybatis.cfg.xml");
            //构建sqlSession的工厂
            sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
    //创建能执行映射文件中sql的sqlSession
    public static SqlSession getSession(){
        return sessionFactory.openSession();
    }
}

13、编写测试文件UserServiceTest.java
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第14张图片

代码如下:

package com.cy.mybatis.service;

import com.cy.mybatis.beans.User;
import com.cy.mybatis.mapper.UserMapper;
import com.cy.mybatis.tools.DBTools;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;

public class UserServiceTest {
    @Test
    //添加操作
    public void insertUser() throws Exception {
        SqlSession session = DBTools.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        User user = new User("香蕉", "8888", 8888.8);
        try {
            mapper.insertUser(user);
            System.out.println(user.toString());
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }
    }

    @Test
    //删除操作
    public void deleteUser() throws Exception {
        SqlSession session=DBTools.getSession();
        UserMapper mapper=session.getMapper(UserMapper.class);
        try {
            mapper.deleteUser(1);
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }
    }

    @Test
    //选择操作
    public void selectUserById() throws Exception {
        SqlSession session=DBTools.getSession();
        UserMapper mapper=session.getMapper(UserMapper.class);
        try {
     //这里用到User类的无参构造方法创建对象,User user=new User();
            User user =mapper.selectUserById(2);
            System.out.println(user.toString());

            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }
    }

    @Test
    public void selectAllUser() throws Exception {
        SqlSession session= DBTools.getSession();
        UserMapper mapper=session.getMapper(UserMapper.class);
        try {
            List user=mapper.selectAllUser();
            System.out.println(user.toString());
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }
    }

}

14、运行,在每个增删改查对应的方法上面运行即可,
3、intellij idea中搭建Mybatis简单例子,并对数据库做增删改查_第15张图片

整体项目打包下载地址:
https://download.csdn.net/download/nba_linshuhao/10671396

遇到的问题
1、数据库表id字段未设置自动递增,这样添加数据会报错,因为本例中无构造方法中没有id,并且UserMapper.xml添加数据中没有添加id字段
2、不会创建mybatis.cfg.xml 和UserMapper.xml

下载之后直接用InteliJ IDEA打开即可运行,注意下看lib下的包有没有加入依赖,没有的话注意加入依赖add as library

这是我亲自运行后总结的,如果还有不明白的可以直接评论,看到后我会为你解答。

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