【MyBatis】-----初识【MyBatis】

一、核心配置文件

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql:///mybatis" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    <!-- 引用映射文件 -->
    <mappers >
        <mapper resource="com/myBatis/mapper/userMapper.xml"/>
    </mappers>
</configuration>

二、实体类

package com.myBatis.entity;

public class EUser {
    private Integer id;
    private String name;
    private Integer age;
    public int getId() {
        return id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    @Override
    public String toString() {
        return "EUser [id=" + id + ", name=" + name + ", age=" + age + "]";
    }
    
    
    
}

三、实体类的映射文件

<?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">
    <!-- 
    为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的 
    -->
    <mapper namespace="com.myBatis.mapper.userMapper.xml">
    
    <!-- 根据id查询得到一个user对象 -->
    <select id="getUser" parameterType="int" resultType="com.myBatis.entity.EUser">
        select * from users where id=#{id}
    </select>
    <!--  根据id查询删除一个user对象 -->
    <delete id="deleteUser" parameterType="com.myBatis.entity.EUser">
        delete from users where id=#{id}
    </delete>
      <!-- 创建用户(Create) -->
    <insert id="addUser" parameterType="com.myBatis.entity.EUser">
        insert into users values(null,#{name},#{age})
    </insert>
     <!-- 修改用户(Update) -->
    <update id="updateUser" parameterType="com.myBatis.entity.EUser">
        update users set name=#{name},age=#{age} where id=#{id}
    </update>
    
    </mapper>

四、测试方法

package myBatisTest;

import java.io.IOException;
import java.io.Reader;

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.Test;

import com.myBatis.entity.EUser;


public class TestUser {
    
    
    
    //修改
    @Test
    public void testUpdateUser() {
        try {
            Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            SqlSession sqlSession= sqlSessionFactory.openSession(true);
            //先查找
             String select = "com.myBatis.mapper.userMapper.xml.getUser";
             EUser  user = sqlSession.selectOne(select, 5);
             System.out.println(user);
             //再修改
            user.setName("改啦2122");
            user.setAge(50);
            String update = "com.myBatis.mapper.userMapper.xml.updateUser";
            int i = sqlSession.update(update, user);
             System.out.println(i);
             EUser  user1= sqlSession.selectOne(select, 5);
             System.out.println(user1);
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }
    
    
    //添加
    @Test
    public void testAddUser() {
        try {
            Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            SqlSession sqlSession= sqlSessionFactory.openSession(true);
             String add = "com.myBatis.mapper.userMapper.xml.addUser";
             EUser user = new EUser();
            user.setName("用户孤傲苍狼");
            user.setAge(20);
            int i = sqlSession.insert(add, user);
             System.out.println(i);
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }
    
    
    //删除
    @Test
    public void testDeleteUser() {
        try {
            Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            /**
             * openSession(true)  手动提交
             * 数据库中的autocommit针对的是数据库自己以及命令窗口，必须在程序手动提交
             */
            SqlSession sqlSession= sqlSessionFactory.openSession(true);
             String delete = "com.myBatis.mapper.userMapper.xml.deleteUser";
             int i= sqlSession.delete(delete, 4);
             System.out.println(i);
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }
    
    
    //查询
    @Test
    public void testGetUser() {
        
        try {
            Reader reader= Resources.getResourceAsReader("SqlMapConfig.xml");
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            SqlSession sqlSession= sqlSessionFactory.openSession(true);
             String select = "com.myBatis.mapper.userMapper.xml.getUser";
             EUser  user = sqlSession.selectOne(select, 1);
             System.out.println(user);
        } catch (IOException e) {
            e.printStackTrace();
        } 
    }
}

注：

类的映射文件中的<mapper namespace="com.myBatis.mapper.userMapper.xml">  映射文件后缀名可不写

测试类中的 String select = "com.myBatis.mapper.userMapper.xml.getUser";   映射文件后缀名可不写

 参考：MyBatis学习总结(一)——MyBatis快速入门