Mybatis学习笔记 【1】

mybatis学习笔记 【1】

1. 创建maven项目并添加相关依赖

       <dependency>
           <groupId>org.mybatisgroupId>
           <artifactId>mybatisartifactId>
           <version>3.4.6version>
       dependency>

       
       <dependency>
           <groupId>junitgroupId>
           <artifactId>junitartifactId>
           <version>4.13.2version>
           <scope>testscope>
       dependency>

       
       <dependency>
           <groupId>mysqlgroupId>
           <artifactId>mysql-connector-javaartifactId>
           <version>5.1.47version>
       dependency>

       
       <dependency>
           <groupId>log4jgroupId>
           <artifactId>log4jartifactId>
           <version>1.2.17version>
       dependency>

       
       <dependency>
           <groupId>org.projectlombokgroupId>
           <artifactId>lombokartifactId>
           <version>1.18.12version>
           <scope>providedscope>
       dependency>

2. 创建数据库和表并添加数据

CREATE DATABASE testdb;

USE testdb;

CREATE TABLE `t_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `address` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

INSERT INTO `t_user` VALUES ('1', '李洪刚', '20', '江阳区嘉裕花园3栋四楼15#');
INSERT INTO `t_user` VALUES ('2', '王云华', '30', '纳溪区大渡镇红鱼村三大队');
INSERT INTO `t_user` VALUES ('3', '郑小翠', '21', '江阳区老窖花园2栋五楼15号');

3. 在resource目录下创建jdbc.properties文件,添加以下内容

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/testdb?useSSL=false
jdbc.username=root
jdbc.password=1

4. 在resource目录下创建mybatis配置文件mybatis-config.xml

<configuration>
    
    <properties resource="jdbc.properties"/>
    
    <typeAliases>
        <package name="com.cxh.entity"/>
    typeAliases>

    <environments default="development">
        <environment id="development">
            <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="mapper/UserDaoMapper.xml"/>
    mappers>
configuration>

5. 创建实体类包entity，创建实体类User

package com.cxh.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
     
    private Integer id;
    private String name;
    private Integer age;
    private String address;
}

6. 创建dao包，创建UserDao

package com.cxh.dao;

import com.cxh.entity.User;

import java.util.List;

public interface UserDao {
     

    User findById(Integer id);
    List<User> findAll();
}

7. 在resource目录下创建mapper文件夹，在mapper文件夹下创建UserDaoMapper.xml

<mapper namespace="com.cxh.dao.UserDao">
    <select id="findById" parameterType="Integer" resultType="User">
        select * from t_user where id=#{id};
    select>

    <select id="findAll" resultType="User">
        select * from t_user;
    select>
mapper>

8. 在resource目录下创建log4j.properties

log4j.rootLogger=WARN, stdout, logfile
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

9. 创建测试类

package com.cxh.mappertest;

import com.cxh.dao.UserDao;
import com.cxh.entity.User;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.Reader;
import java.util.List;

/**
 * 测试用户操作
 */
public class TestUserOperation {
     

    private SqlSession sqlSession; //sql会话


    @Before
    public void init() throws IOException {
     
        //读取mybatis配置文件
        Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
        //基于mybatis配置文件构建sql会话工厂
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        //通过工场获得链接对象
        sqlSession = sqlSessionFactory.openSession();
        System.out.println("sqlSession启动...");
    }

    @Test
    public void testFindId(){
     
        int id = 1;
        //通过接口获取接口实现类对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        User user = mapper.findById(id);
        System.out.println(user == null? "id为["+id+"]的用户未找到" : user);
    }

    @Test
    public void testFindAll(){
     
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        List<User> users = mapper.findAll();
        users.forEach(System.out :: println);
    }

    @After
    public void destroy(){
     
        sqlSession.close();
        System.out.println("sqlSession关闭...");
    }
}

运行结果