mybatis 注解crud

1、接口

package com.wt.dao;

import com.wt.pojo.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface UserMapper {
    @Select("select * from user")
    List<User> getUserList();
}

2、xml 配置文件

   <mappers>
        <mapper class="com.wt.dao.UserMapper"/>
    </mappers>

3、测试使用

package com.wt.dao;

import com.wt.pojo.User;
import com.wt.utils.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserMapperTest {
    @Test
    public void getUserList(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = userMapper.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }
}

局限性

注解不是适用于复杂的sql语句(官网原话)，没有resultMap 数据库字段名和javaBean的字段名不同

案例

注解的crud

接口类

package com.wt.dao;

import com.wt.pojo.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserMapper {
    @Select("select * from user")
    List<User> getUserList();
    /*
    @Param 注解 
    1. 基本数据类型和 String类型 添加 改注解
    2. 其它引用数据类型不添加此注解
    3. 注解的名称，是查询语句的变量名
    4. xml映射文件 和 注解都可以使用
    5. 单个变量，加不加 Param 没有区别，但推荐添加
    */
    // 查
    @Select("select * from mybatis.user where id = #{uid}")
    User getUserById(@Param("uid") int id);

    // 增
    @Insert("insert into user(name, pwd) values(#{name}, #{password})")
    int insertUser(@Param("name") String name, @Param("password") String pwd);

    // 改
    @Update("update user set name= #{username} where id = #{uid}")
    int updateUser(@Param("username") String name, @Param("uid") int id);

    // 删
    @Delete("delete from user where id = #{uid}")
    int deleteUserByiD(@Param("uid") int id);
}

2、xml配置文件 mapper同上 用 class

3、测试

package com.wt.dao;

import com.wt.pojo.User;
import com.wt.utils.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserMapperTest {
    @Test
    public void getUserList(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = userMapper.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }

    @Test
    public void getUserByiD(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        User userById = userMapper.getUserById(1);
        System.out.println(userById);
        sqlSession.close();
    }

    @Test
    public void insertUser(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        int insertId = userMapper.insertUser("to", "12345");
        sqlSession.commit();
        System.out.println(insertId);
        sqlSession.close();
    }

    @Test
    public void updateUser(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        userMapper.updateUser("xx", 6);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void deleteUser(){
        SqlSession sqlSession = MyBatisUtil.getSession();
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        userMapper.deleteUserByiD(5);
        sqlSession.commit();
        sqlSession.close();
    }
}