MyBatis学习总结(二)——使用MyBatis对表执行CRUD操作 MyBatis学习总结(一)——MyBatis入门学习

该文章是在上篇文章 MyBatis学习总结(一)——MyBatis入门学习 的基础上添加的MyBatis对CRUD的操作

一、使用MyBatis对表执行CRUD操作——基于XML的实现

1、定义sql映射xml文件

　　userMapper.xml文件的内容如下：

<?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
      例如namespace="com.myl.mapping.userMapper"就是com.myl.mapping(包名)+userMapper(userMapper.xml文件去除后缀)
 -->
 
<mapper namespace="com.myl.entity.userMapper">

 <!-- 
     在select标签中编写查询的SQL语句， 设置select标签的id属性为getUser，id属性值必须是唯一的，不能够重复
      使用parameterType属性指明查询时使用的参数类型，resultType属性指明查询返回的结果集类型
    resultType="com.myl.entity.User"就表示将查询结果封装成一个User类的对象返回
    User类就是users表所对应的实体类
  -->
 
  <!--根据id查询得到一个user对象-->
 
    <select id="getUser" parameterType="int" resultType="com.myl.entity.User">
        select * from user where id=#{id}
    </select>
    
    <!-- 查找所有数据 -->
    <select id="getAllUser" resultType="com.myl.entity.User">
        select * from user
    </select>
    
    <!-- 添加数据 -->
    <insert id="addUser" parameterType="com.myl.entity.User">
        insert into user (name,age,job,deptno,hdate) values (#{name},#{age},#{job},#{deptno},#{hdate, jdbcType=DATE})
    </insert>
    
    <!-- 修改数据 -->
    <update id="updateUser" parameterType="com.myl.entity.User">
        update user set name=#{name},age=#{age},job=#{job},deptno=#{deptno},hdate=#{hdate} where id=#{id}
    </update>
    
    <!-- 删除数据 -->
    <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id}
    </delete>

</mapper>

单元测试代码TestCRUD.java

package com.myl;

import java.util.Date;
import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.myl.entity.User;
import com.myl.util.MybatisUtil;
/**
 * 测试 CRUD
 * @author myl
 * @date      2018年4月22日   上午11:23:43
 */
public class TestCRUD {

    @Test
    public void getUserById() {
        SqlSession sqlSession = MybatisUtil.getSession();
        /**
         * 执行操作，getUser 为select的id属性值
         */
        User user = sqlSession.selectOne("getUser", 1);
        System.out.println(user);
        //使用sqlSession执行完sql之后，关闭sqlSession
        sqlSession.close();
    }
    
    @Test
    public void getAllUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        
        /**
         * 执行查询操作，将查询结果自动封装成List<User>返回
         * getAllUser 为select标签的id属性值
         */
        List<User> userList = sqlSession.selectList("getAllUser");
        
        for(User user : userList){
            System.out.println(user);
        }
        sqlSession.close();
    }
    
    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        User user = new User();
        user.setName("maoyl");
        user.setAge(15);
        user.setJob("java");
        user.setDeptno(1);
        user.setHdate(new Date());
        /**
         * 执行添加操作
         * addUser为insert的id属性值
         */
        int result = sqlSession.insert("addUser", user);
        /**
         * 手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(true); 则不必手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(false); 需要手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(); 需要手动提交事务
         */
        sqlSession.commit();
        sqlSession.close();
        System.out.println(result);
        
    }
    
    @Test
    public void update(){
        SqlSession sqlSession = MybatisUtil.getSession();
        
        User user = sqlSession.selectOne("getUser", 8);
        if(user == null){
            System.out.println("未查找到数据");
            return;
        }
        user.setName("tangt");
        user.setAge(2);
        user.setJob("techer");
        user.setHdate(new Date());
        int result = sqlSession.update("updateUser", user);
        /**
         * 手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(true); 则不必手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(false); 需要手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(); 需要手动提交事务
         */
        sqlSession.commit();
        sqlSession.close();
        System.out.println(result);
        
    }
    
    @Test
    public void deleteUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        //若有该数据 result返回 1 删除成功 。若无该数据则result返回 0
        int result = sqlSession.delete("deleteUser", 8);
        /**
         * 手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(true); 则不必手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(false); 需要手动提交事务
         * 若 SqlSession sqlSession = MybatisUtil.getSession(); 需要手动提交事务
         */
        sqlSession.commit();
        sqlSession.close();
        System.out.println(result);
    }

}

用到的Mybatis工具类

package com.myl.util;

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;

/**
 * @author myl
 * @date      2018年4月22日   上午11:04:57
 * 获取 SqlSessionFactory SqlSession 对象的工具类
 */
public class MybatisUtil {
    
    /**
     * 获取SqlSessionFactory
     * @return:         SqlSessionFactory   
     * @throws
     */
    public static SqlSessionFactory getSessionFactory(){
        String conf = "mybatisConf.xml";
        Reader reader;
        SqlSessionFactory factory = null;
        try {
            reader = Resources.getResourceAsReader(conf);
            factory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return factory;
    }
    
    /**
     * 获取 SqlSession
     * @return:         SqlSession   
     * @throws
     */
    public static SqlSession getSession(){
        return getSessionFactory().openSession();
    }
    
    /**
     * 获取 SqlSession 
     * 注：
     *         true 表示创建的SqlSession的对象在执行完sql之后会自动提交事务
     *         false 表示创建的SqlSession的对象在执行完sql之后不会自动提交事务，则需要我们手动提交， 调用sqlSession.commit()即可
     * @param:             @param isAutoCommit
     * @return:         SqlSession   
     * @throws
     */
    public static SqlSession getSession(boolean isAutoCommit){
        return getSessionFactory().openSession(isAutoCommit);
    }
    
}

所有测试均通过

二、使用MyBatis对表执行CRUD操作——基于注解的实现

1、定义sql映射的接口

　　UserMapperInter接口的代码如下：

package com.myl.mapping;

import java.util.List;

import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import com.myl.entity.User;

public interface UserMapperInter {
    
    @Select("select * from user where id = #{id}")
    public User getUserById(int id);
    
    @Select("select * from user")
    public List<User> getAllUser();
    
    @Insert("insert into user (name,age,job,hdate,deptno) values (#{name},#{age},#{job},#{hdate},#{deptno})")
    public int addUser(User user);
    
    @Update("update user set name = #{name}, age = #{age}, hdate = #{hdate}, deptno = #{deptno} where id = #{id}")
    public int updateUser(User user);
    
    @Delete("delete from user where id = #{id}")
    public int deleteUser(int id);
    
}

需要说明的是，我们不需要针对UserMapperI接口去编写具体的实现类代码，这个具体的实现类由MyBatis帮我们动态构建出来，我们只需要直接拿来使用即可。

　　2、在conf.xml文件中注册这个映射接口

<?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://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
      <!-- 
        注册userMapper.xml文件， 
         userMapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/userMapper.xml
        -->
        <mapper resource="com/myl/mapping/userMapper.xml"/>
        
        <!-- 注册UserMapper映射接口-->
        <mapper class="com.myl.mapping.UserMapperInter" />
    </mappers>
    
</configuration>

单元测试类的代码：

package com.myl;


import java.util.Date;
import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.myl.entity.User;
import com.myl.mapping.UserMapperInter;
import com.myl.util.MybatisUtil;

public class TestCRUD2 {

    @Test
    public void getUserById() {
        SqlSession sqlSession = MybatisUtil.getSession();
        UserMapperInter mapper = sqlSession.getMapper(UserMapperInter.class);
        User user = mapper.getUserById(1);
        System.out.println(user);
        sqlSession.close();
    }
    
    @Test
    public void getAllUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        UserMapperInter mapper = sqlSession.getMapper(UserMapperInter.class);
        List<User> userList = mapper.getAllUser();
        for(User user : userList){
            System.out.println(user);
        }
        sqlSession.close();
    }
    
    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        UserMapperInter mapper = sqlSession.getMapper(UserMapperInter.class);
        User user = new User();
        user.setName("xqt");
        user.setAge(22);
        user.setJob("java");
        user.setDeptno(4);
        user.setHdate(new Date());
        int result = mapper.addUser(user);
        System.out.println(result);
        sqlSession.commit();
        sqlSession.close();
    }
    
    @Test
    public void updateUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        UserMapperInter mapper = sqlSession.getMapper(UserMapperInter.class);
        User user = mapper.getUserById(11);
        System.out.println(user);
        if(user == null){
            System.out.println("没有该用户");
            return;
        }
        user.setName("myl");
        user.setAge(2);
        user.setDeptno(3);
        int result = mapper.updateUser(user);
        System.out.println(result);
        sqlSession.commit();
        sqlSession.close();
    }
    
    @Test
    public void deleteUser(){
        SqlSession sqlSession = MybatisUtil.getSession();
        UserMapperInter mapper = sqlSession.getMapper(UserMapperInter.class);
        //如果返回 0 则删除的用户不存在，删除失败
        int result = mapper.deleteUser(12);
        System.out.println(result);
        sqlSession.commit();
        sqlSession.close();
    }

}

所有测试均通过