mybatis学习-02-增删改查
2022/2/1 23:11:18
本文主要是介绍mybatis学习-02-增删改查,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
总流程:
1.编写接口
2.编写对应的mapper中的sql语句
3.测试
1. namespace
namespace中的包名要和Dao/Mapper中的接口保持一致!
2. select
选择,查询语句:
- id:就是对应的namespace中的方法名;
- resulType:sql语句执行的返回值!
- parameterType:参数类型
注意增删改需要提交事务!
userMapper.java接口:
package com.zuo.dao; import com.zuo.pojo.User; import java.util.List; /** * @description */ public interface UserMapper { //查询全部用户 List<User> getUserList(); //根据id查用户 User getUserById(int id); //insert一个用户 int addUser(User user); //修改用户 int updateUser(User user); //删除一个用户 int deleteUser(int id); }
userMapper.xml接口对应的mapper
<?xml version="1.0" encoding="UTF8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.zuo.dao.UserMapper"> <select id="getUserList" resultType="com.zuo.pojo.User">select * from mybatis.user</select> <select id="getUserById" parameterType="int" resultType="com.zuo.pojo.User">select * from user where id = #{id}</select> <insert id="addUser" parameterType="com.zuo.pojo.User">insert into user (id,name,pwd) values (#{id},#{name},#{pwd})</insert> <update id="updateUser" parameterType="com.zuo.pojo.User">update user set name=#{name},pwd=#{pwd} where id= #{id}</update> <delete id="deleteUser" parameterType="int">delete from user where id=#{id}</delete> </mapper>
UserMapperTest.java测试:
package com.zuo.dao; import com.zuo.pojo.User; import com.zuo.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; /** * @description */ public class UserMapperTest { @Test public void test(){ //第一步:获取sqlSession对象 SqlSession sqlSession = MybatisUtils.getSqlSession(); //方式一:getMapper执行sql UserMapper userMapper = sqlSession.getMapper(UserMapper.class); List<User> userList = userMapper.getUserList(); for(User user: userList){ System.out.println(user); } //关闭sqlSession sqlSession.close(); } @Test public void getUserById(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = userMapper.getUserById(1); System.out.println(user); sqlSession.close(); } @Test public void addUser(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper userMapper = sqlSession.getMapper(UserMapper.class); int res = userMapper.addUser(new User(10, "afa", "123")); if(res>0) { System.out.println("插入成功!"); } //提交事务 sqlSession.commit();//提交事务 sqlSession.close(); } @Test public void updateUser(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); int res = mapper.updateUser(new User(10, "haha", "12345")); if(res>0) { System.out.println("修改成功!"); } sqlSession.commit();//提交事务 sqlSession.close(); } @Test public void deleteUser(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); mapper.deleteUser(10); sqlSession.commit();//提交事务 sqlSession.close(); } }
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