MyBatis（三）代理Dao方式的CRUD操作

目录

一、代理Dao方式的CRUD操作

test

mapper

sql

一、代理Dao方式的CRUD操作

在入门案例中有很多重复的地方进行提取

@Before
    public void init() throws Exception {
        // 加载配置文件
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        // 创建工厂对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 创建Session对象
        session = factory.openSession();
        // 获取到代理对象
        mapper = session.getMapper(UserMapper.class);
    }

 @After
    public void destory() throws IOException {
        in.close();
        session.close();
    }

把befor和after提取出来后，再进行测试就简便了许多

test

/**
     * 测试查询所有的方法
     * @throws Exception 
     */
    @Test
    public void testFindAll() throws Exception {
        List<User> list = mapper.findAll();
        // 遍历
        for (User user : list) {
            System.out.println(user);
        }
        in.close();
    }
    
    @Test
    public void testFindById() throws Exception {
        User user = mapper.findById(41);
        System.out.println(user);
        in.close();
    }
​
    @Test
    public void testInsert() throws Exception {
        User user = new User();
        user.setUsername("美美");
        user.setBirthday(new Date());
        user.setSex("男");
        user.setAddress("顺义");
        mapper.insert(user);
        session.commit();
         System.out.println(user.getId());
    }
    
    @Test
    public void testUpdate() throws Exception {
        User user = mapper.findById(41);
        user.setUsername("小凤");
        mapper.update(user);
        session.commit();
    }
    
    @Test
    public void testDelete() throws Exception {
        mapper.delete(48);
        session.commit();
    }
    
    // 第一种
    @Test
    public void testFindByName() throws Exception {
        List<User> list = mapper.findByName("%王%");
        for (User user : list) {
            System.out.println(user);
        }
    }
    // 第二种
    @Test
    public void testFindByName() throws Exception {
        List<User> list = mapper.findByName("王");
        for (User user : list) {
            System.out.println(user);
        }
    }
    
    @Test
    public void testFindByCount() throws Exception {
        Integer count = mapper.findByCount();
        System.out.println("总记录数："+count);
    }
    

mapper

public interface UserMapper {
    
    public List<User> findAll();
    
    public User findById(Integer userId);
    
    public void insert(User user);
    
    public void update(User user);
    
    public void delete(Integer userId);
    
    public List<User> findByName(String username);
    
    public Integer findByCount();
    
}

sql

<?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.qcbyjy.mapper.UserMapper">
    <select id="findAll" resultType="com.qcbyjy.domain.User">
        select * from user
    </select>
    
    <!-- 
        通过id查询 
        SQL语句使用#{占位符的名称，名称可以任意}，仅限于基本数据类型和String类型
    -->
    <select id="findById" resultType="com.qcbyjy.domain.User" parameterType="int">
        select * from user where id = #{id};
    </select>
    
    <!--保存操作-->
    <insert id="insert" parameterType="com.qcbyjy.domain.User">
        /*
          keyProperty表示要返回的属性名称
          order取值AFTER表示插入数据后的行为
          resultType表示返回值的类型
        */
        <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
            select last_insert_id();
        </selectKey>
        insert into user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})
    </insert>
    
    <!-- 修改 -->
    <update id="update" parameterType="com.qcbyjy.domain.User">
        update user set username = #{username},birthday = #{birthday},sex = #{sex},address=#{address} where id = #{id}
    </update>
    
    <!-- 删除 -->
    <delete id="delete" parameterType="Integer">
        delete from user where id = #{id}
    </delete>
    
    <!-- 模糊查询 -->
    <select id="findByName" resultType="com.qcbyjy.domain.User" parameterType="string">
        <!-- 第一种方式的SQL语句 
        select * from user where username  like #{username}
        -->
        <!-- 第二章SQL语句的编写 强调：'%${value}%'不能修改，固定写法（不推荐使用）  -->
        select * from user where username  like '%${value}%'
    </select>
    
    <!-- 具体函数的查询 -->
    <select id="findByCount" resultType="int">
        select count(*) from user
    </select>
    
</mapper>