注解的增删改查

package com.kuang.dao;

import com.kuang.pojo.User;
import org.apache.ibatis.annotations.*;
import org.junit.Test;

import java.util.List;
import java.util.Map;

public interface UserMapper {
@Select("select * from mybatis.user")
List<User> getUsers();
@Select("select * from user where id=#{id}")
User getUserById(@Param("id") int id);
@Insert("insert into user (id,name,pwd) values(#{id},#{name},#{password})")
int add(User user);
@Update("update user set name=#{name},pwd=#{pwd} where id =#{id}")
int update(Map<String,Object> map);
@Delete("delete from user where id =#{id}")
int Delete(@Param("id") int id);

}

import com.kuang.dao.UserMapper;
import com.kuang.pojo.User;
import com.kuang.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.HashMap;
import java.util.List;

public class UserMapperTest {

    @Test
    public void test(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> users = mapper.getUsers();
        for (User user : users) {
            System.out.println(user);
        }
        sqlSession.close();
    }

    @Test
    public void getUserById(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.getUserById(2);
        System.out.println(user);


        sqlSession.close();
    }

    @Test
    public void add(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int i = mapper.add(new User(5, "机身", "200103012"));
        if (i>0){
            System.out.println("插入成功");
        }
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void update(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        HashMap<String, Object> map = new HashMap<String, Object>();
        map.put("id",5);
        map.put("name","牛");
        map.put("pwd","20013");
        mapper.update(map);
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void Delete(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
         mapper.Delete(5);
         sqlSession.commit();


        sqlSession.close();
    }
}

 sql复杂要么维护老系统，要么就是小系统吧，微服务架构好，之前我们那个贼大的项目最长的sql才两行

 

<mappers>
      <!--绑定接口-->
    <mapper class="com.kuang.dao.UserMapper"/>
</mappers>

通配 

 三种方式

@Param注意事项

 #{} 与 ${}的区别

#{}是PrepareStatement有预编译，防止SQL注入问题

${}是普通的Statement没有预编译，可能会SQL注入