参考官网：https://mybatis.org/mybatis-3/zh/index.html

1.搭建数据库环境

CREATE DATABASE `mybatis`;

USE `mybatis`;

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (
`id` int(20) NOT NULL,
`name` varchar(30) DEFAULT NULL,
`pwd` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert  into `user`(`id`,`name`,`pwd`) values (1,'奔奔','123456'),(2,'张三','123456'),(3,'李四','123456');

 2.导入MyBatis相关jar包

<dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis</artifactId>
   <version>3.5.2</version>
</dependency>
<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>5.1.47</version>
</dependency>

 3.引入MyBatis所需要的db.properties文件 

 　　下面这个是固定的文件，可以复用

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybaits?useSSL=true&useUnicode=true&\
  characterEncoding=UTF-8&serverTimezone=UTC
username=root
password=123456

 4.编写MyBatis核心配置文件

　　这个文件在配置好以后，一般很少有改变

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--引入外部配置文件-->
    <properties resource="db.properties"/>
    <!--给实体类写别名-->
    <typeAliases>
        <package name="com.ben.pojo"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>
<mappers>
    <mapper resource="UserMapper.xml"/>
</mappers>
</configuration>

5.创建实体类User

package com.ben.pojo;

public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

6.编写MyBatis工具类

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.IOException;
import java.io.InputStream;

public class MybatisUtils {

   private static SqlSessionFactory sqlSessionFactory;

   static {
       try {
           String resource = "mybatis-config.xml";
           InputStream inputStream = Resources.getResourceAsStream(resource);
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
      } catch (IOException e) {
           e.printStackTrace();
      }
  }

   //获取SqlSession连接
   public static SqlSession getSession(){
       return sqlSessionFactory.openSession();
  }

}

 7.编写Mapper接口类(相当于dao层的接口) 

package com.ben.dao;
import com.ben.pojo.User;
import java.util.List;
public interface UserMapper {
    //查询全部用户
    List<User> getUserList();
    //根据id查询用户
    User getUserById(int id);//里面的参数就是sql语句中要填写的参数，见test类
    //insert一个用户
    int addUser(User user);
    //修改用户
    int updateUser(User user);
    //删除一个用户
    int deleteUser(int id);
}

8.编写Mapper.xml配置文件
　　namespace 十分重要，不能写错！

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ben.dao.UserMapper">
   <select id="getUserList" resultType="User">
       select * from mybaits.user
   </select>
    <select id="getUserById" parameterType="int"
            resultType="com.ben.pojo.User">
        select* from mybaits.user where id=#{id}
    </select>
    <insert id="addUser" parameterType="com.ben.pojo.User">
        insert into mybaits.user(id,name,pwd) values(#{id},#{name},#{pwd})
    </insert>
    <update id="updateUser" parameterType="com.ben.pojo.User">
        update mybaits.user set name=#{name},pwd=#{pwd} where id=#{id};
    </update>
    <delete id="deleteUser" parameterType="int">
        delete from mybaits.user where id=#{id};
    </delete>
</mapper>

9.编写测试类

package dao;
import com.ben.dao.UserMapper;
import com.ben.pojo.User;
import com.ben.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper userDao = sqlSession.getMapper(UserMapper.class);
        List<User> userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }
    @Test
    public void testGetUserById(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }
    @Test
    public void TestAddUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int result = mapper.addUser(new User(3, "李四", "123123"));
        System.out.println(result);
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void testUpdateUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.updateUser(new User(3,"王二麻","123123"));
        sqlSession.commit();
        sqlSession.close();
    }
    @Test
    public void testDeleteUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.deleteUser(3);
        sqlSession.commit();
        sqlSession.close();
    }
}

 

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