【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>

SqlMapConfig.xml

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 + "]";
     }

 }

EUser.java

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>

userMapper.xml

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();
         }
     }
 }

TestUser.java

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