### 修改UserMapper ```java package com.gosuncn.dao; import com.gosuncn.entity.User; public interface UserMapper { void saveUser(User user); } ``` ### 修改UserMapper.xml ```xml <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.gosuncn.dao.UserMapper"> <insert id="saveUser" parameterType="com.gosuncn.entity.User"> <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer"> select last_insert_id() </selectKey> insert into user (name, age, address) values (#{name}, #{age}, #{address}) </insert> </mapper> ``` ### 修改MainTest ```java package com.gosuncn; import com.gosuncn.dao.UserMapper; import com.gosuncn.entity.User; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.InputStream; public class MainTest { public static void main(String[] args) throws Exception { InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml"); SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession sqlSession = sessionFactory.openSession(); UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = new User(); user.setName("ABC"); user.setAge(26); user.setAddress("BeiJin"); System.out.println(user); userMapper.saveUser(user); System.out.println(user); sqlSession.commit(); sqlSession.close(); inputStream.close(); } } ``` > user对象在保存前和保存后的id字段，一个是null，一个有值。