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

　　UserMapperI接口的代码如下：

package me.gacl.mapping;

import java.util.List;
import me.gacl.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

/**
 * @author gacl
 * 定义sql映射的接口，使用注解指明方法要执行的SQL
 */
public interface UserMapperI {

    //使用@Insert注解指明add方法要执行的SQL
    @Insert("insert into users(name, age) values(#{name}, #{age})")
    public int add(User user);
    
    //使用@Delete注解指明deleteById方法要执行的SQL
    @Delete("delete from users where id=#{id}")
    public int deleteById(int id);
    
    //使用@Update注解指明update方法要执行的SQL
    @Update("update users set name=#{name},age=#{age} where id=#{id}")
    public int update(User user);
    
    //使用@Select注解指明getById方法要执行的SQL
    @Select("select * from users where id=#{id}")
    public User getById(int id);
    
    //使用@Select注解指明getAll方法要执行的SQL
    @Select("select * from users")
    public List getAll();
}

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

测试类代码

package me.gacl.test;

import java.util.List;
import me.gacl.domain.User;
import me.gacl.mapping.UserMapperI;
import me.gacl.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

public class TestCRUDByAnnotationMapper {

    @Test
    public void testAdd(){
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        //得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        User user = new User();
        user.setName("用户xdp");
        user.setAge(20);
        int add = mapper.add(user);
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(add);
    }
    
    @Test
    public void testUpdate(){
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        //得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        User user = new User();
        user.setId(3);
        user.setName("孤傲苍狼_xdp");
        user.setAge(26);
        //执行修改操作
        int retResult = mapper.update(user);
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }
    
    @Test
    public void testDelete(){
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        //得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        //执行删除操作
        int retResult = mapper.deleteById(7);
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(retResult);
    }
    
    @Test
    public void testGetUser(){
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        //得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        //执行查询操作，将查询结果自动封装成User返回
        User user = mapper.getById(8);
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(user);
    }
    
    @Test
    public void testGetAll(){
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        //得到UserMapperI接口的实现类对象，UserMapperI接口的实现类对象由sqlSession.getMapper(UserMapperI.class)动态构建出来
        UserMapperI mapper = sqlSession.getMapper(UserMapperI.class);
        //执行查询操作，将查询结果自动封装成List返回
        List lstUsers = mapper.getAll();
        //使用SqlSession执行完SQL之后需要关闭SqlSession
        sqlSession.close();
        System.out.println(lstUsers);
    }
}