一、需求

向数据库插入一条记录后，希望能立即拿到这条记录在数据库中的主键值。

二、代码演示

1、方式1 - useGeneratedKeys

• 数据库环境

  CREATE DATABASE `mybatis_db`;
  USE `mybatis_db`;
  CREATE TABLE `user` (`id` INT(11) NOT NULL AUTO_INCREMENT,`username` VARCHAR(32) NOT NULL COMMENT '用户名称',`birthday` DATETIME DEFAULT NULL COMMENT '生日',`sex` CHAR(1) DEFAULT NULL COMMENT '性别',`address` VARCHAR(256) DEFAULT NULL COMMENT '地址',PRIMARY KEY (`id`)
  ) ENGINE=INNODB DEFAULT CHARSET=utf8;-- insert.... 
  INSERT INTO USER(id,username,birthday,sex,address) VALUES (1,'tom','2024-01-01 00:00:00','男','北京'),(2,'jerry','2023-01-01 00:00:00','男','上海');
  

  

• pom依赖

  <?xml version="1.0" encoding="UTF-8"?>
  <project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>mybatis-dao</artifactId><version>1.0-SNAPSHOT</version><!--指定编码及版本--><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.encoding>UTF-8</maven.compiler.encoding><java.version>1.11</java.version><maven.compiler.source>1.11</maven.compiler.source><maven.compiler.target>1.11</maven.compiler.target></properties><!--引入相关依赖--><dependencies><!--引入mybatis依赖--><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.3</version></dependency><!--引入mysql驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.47</version></dependency><!--引入junit--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version></dependency></dependencies></project>
  

• SqlMapConfig.xml

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><properties resource="jdbc.properties"></properties><typeAliases><!--方式一：给单个实体起别名-->
  <!--        <typeAlias type="domain.User" alias="user"></typeAlias>--><!--方式二：批量起别名 别名就是类名，且不区分大小写--><package name="domain"/></typeAliases><!--环境配置--><environments default="mysql"><!--使用mysql环境--><environment id="mysql"><!--使用jdbc事务管理亲--><transactionManager type="JDBC"></transactionManager><!-- 使用连接池--><dataSource type="POOLED"><property name="driver" value="${jdbc.driver}"/><property name="url" value="${jdbc.url}"/><property name="username" value="${jdbc.username}"/><property name="password" value="${jdbc.password}"/></dataSource></environment></environments><!--加载映射配置--><mappers><mapper resource="mapper/UserMapper.xml"></mapper></mappers></configuration>
  

• User实体类

  package domain;import java.util.Date;public class User {private Integer id;private String usernameabc;private Date birthday;private String sex;private String address;public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public Date getBirthday() {return birthday;}public void setBirthday(Date birthday) {this.birthday = birthday;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public String getUsernameabc() {return usernameabc;}public void setUsernameabc(String usernameabc) {this.usernameabc = usernameabc;}@Overridepublic String toString() {return "User{" +"id=" + id +", usernameabc='" + usernameabc + '\'' +", birthday=" + birthday +", sex='" + sex + '\'' +", address='" + address + '\'' +'}';}
  }

• UserMapper.xml

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="mapper.UserMapper"><!--id : 标签的唯一标识type: 封装后实体类型--><resultMap id="userResultMap" type="domain.User"><!--手动配置映射关系--><!--id: 用来配置主键--><id property="id" column="id"></id><!-- result: 表中普通字段的封装--><result property="usernameabc" column="username"></result><result property="birthday" column="birthday"></result><result property="sex" column="sex"></result><result property="address" column="address"></result></resultMap><!--返回主键：方式1注意：只适用于主键自增的数据库，mysql 和 sqlserver 支持，oracle 不支持 --><insert id="save1" parameterType="user" useGeneratedKeys="true" keyProperty="id">insert into user(username, birthday, sex, address)values (#{usernameabc}, #{birthday}, #{sex}, #{address})</insert></mapper>
  

• UserMapper.java

  package mapper;import domain.User;import java.util.List;public interface UserMapper {public void save1(User user);}

• 测试类

  package test;import domain.User;
  import mapper.UserMapper;
  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 org.junit.Test;import java.io.InputStream;
  import java.util.List;public class MybatisTest {//返回主键：方式1@Testpublic void testSave1() throws Exception {InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = new User();user.setUsernameabc("张三");user.setBirthday(new Date());user.setSex("男");user.setAddress("河南");mapper.save1(user);sqlSession.commit();System.out.println("获取返回user的id：" + user.getId());sqlSession.close();}}

• 测试结果

  

2、方式2-selectKey

• UserMapper.java

  package mapper;import domain.User;import java.util.List;public interface UserMapper {public void save1(User user);public void save2(User user);}

• UserMapper.xml

  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="mapper.UserMapper"><!--id : 标签的唯一标识type: 封装后实体类型--><resultMap id="userResultMap" type="domain.User"><!--手动配置映射关系--><!--id: 用来配置主键--><id property="id" column="id"></id><!-- result: 表中普通字段的封装--><result property="usernameabc" column="username"></result><result property="birthday" column="birthday"></result><result property="sex" column="sex"></result><result property="address" column="address"></result></resultMap><!--返回主键：方式1注意：只适用于主键自增的数据库，mysql 和 sqlserver 支持，oracle 不支持 --><insert id="save1" parameterType="user" useGeneratedKeys="true" keyProperty="id">insert into user(username, birthday, sex, address)values (#{usernameabc}, #{birthday}, #{sex}, #{address})</insert><!--返回主键：方式2--><!--selectKey 适用范围广，支持所有类型数据库keyColumn="id" 指定主键列名keyProperty="id" 指定主键封装到实体的 id 属性中resultType="int" 指定主键类型order="AFTER" 设置在 sql 语句执行前（后），执行此语句--><insert id="save2" parameterType="user"><selectKey keyColumn="id" keyProperty="id" resultType="int" order="AFTER">select LAST_INSERT_ID()</selectKey>insert into user(username, birthday, sex, address)values (#{usernameabc}, #{birthday}, #{sex}, #{address})</insert></mapper>
  

• 测试类

  package test;import domain.User;
  import mapper.UserMapper;
  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 org.junit.Test;import java.io.InputStream;
  import java.util.List;public class MybatisTest {//返回主键：方式1@Testpublic void testSave1() throws Exception {InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = new User();user.setUsernameabc("张三");user.setBirthday(new Date());user.setSex("男");user.setAddress("河南");mapper.save1(user);sqlSession.commit();System.out.println("获取返回user的id：" + user.getId());sqlSession.close();}//返回主键：方式2@Testpublic void testSave2() throws Exception {InputStream resourceAsStream = Resources.getResourceAsStream("SqlMapConfig.xml");SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);SqlSession sqlSession = sqlSessionFactory.openSession();UserMapper mapper = sqlSession.getMapper(UserMapper.class);User user = new User();user.setUsernameabc("李四");user.setBirthday(new Date());user.setSex("男");user.setAddress("河北");mapper.save2(user);sqlSession.commit();System.out.println("获取返回user的id：" + user.getId());sqlSession.close();}}

• 测试结果