准备工作:创建在com.jiang.pojo
中创建实体类
package com.jiang.pojo;
import lombok.Data;
//实体类
@Data
public class User {
private int id;
private String name;
private String pwd;
}
1、namespace
namespace中的包名要和 Dao/mapper 接口的包名一致!
2、select
选择,查询语句;
- id : 就是对应的namespace中的方法名;
- resultType:Sql语句执行的返回值!
- parameterType : 参数类型!
编写
UserMapper
接口//根据ID查询用户 User getUserById(int id);
编写对应的
UserMapper
中的sql语句<select id="getUserById" parameterType="int" resultType="com.jiang.pojo.User"> select * from mybatis.user where id = #{id} </select>
测试
@Test public void getUserById() { SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); User user = mapper.getUserById(1); System.out.println(user); sqlSession.close(); }
3、Insert
编写
UserMapper
接口//insert一个用户 int addUser(User user);
编写对应的
UserMapper
中的sql语句<insert id="addUser" parameterType="com.jiang.pojo.User"> insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd}); </insert>
测试
package com.jiang.dao; import com.jiang.pojo.User; import com.jiang.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; public class UserDaoTest { @Test public void getUserLike(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); int i = mapper.addUser(new User(5, "姜嘉航","465123")); if (i>0){ System.out.println("插入成功"); } //提交事务 sqlSession.commit(); sqlSession.close(); } }
4、update
编写
UserMapper
接口//修改用户 int updateUser(User user);
编写对应的
UserMapper
中的sql语句<update id="updateUser" parameterType="com.jiang.pojo.User"> update mybatis.user set name=#{name},pwd=#{pwd} where id = #{id} ; </update>
测试
package com.jiang.dao; import com.jiang.pojo.User; import com.jiang.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; public class UserDaoTest { @Test public void getUserLike(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); int i = mapper.updateUser(new User(5, "哈哈","1265123")); if (i>0){ System.out.println("更新成功"); } //提交事务 sqlSession.commit(); sqlSession.close(); } }
5、Delete
编写
UserMapper
接口//删除一个用户 int deleteUser(int id);
编写对应的
UserMapper
中的sql语句<delete id="deleteUser" parameterType="int"> delete from mybatis.user where id = #{id}; </delete>
测试
package com.jiang.dao; import com.jiang.pojo.User; import com.jiang.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; public class UserDaoTest { @Test public void getUserLike(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); UserMapper mapper = sqlSession.getMapper(UserMapper.class); mapper.deleteUser(5); System.out.println("删除成功"); sqlSession.commit(); sqlSession.close(); } }
注意点:
- 增删改需要提交事务!( sqlSession.commit();)