獲取自增主鍵的值：
mysql支持自增主鍵，自增主鍵值的獲取，mybatis也是利用statement.getGenreatedKeys()；
useGeneratedKeys="true"；使用自增主鍵獲取主鍵值策略
keyProperty；指定對應的主鍵屬性，也就是mybatis獲取到主鍵值以後，將這個值封裝給javaBean的哪個屬性

1、接口定義

package com.mybatis.dao;

import com.mybatis.bean.Employee;

public interface EmployeeMapper {
    public void addEmp(Employee employee);
}

2、mapper定義

<?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.mybatis.dao.EmployeeMapper">
    <!-- parameterType：參數類型，可以省略，
	獲取自增主鍵的值：
		mysql支持自增主鍵，自增主鍵值的獲取，mybatis也是利用statement.getGenreatedKeys()；
		useGeneratedKeys="true"；使用自增主鍵獲取主鍵值策略
		keyProperty；指定對應的主鍵屬性，也就是mybatis獲取到主鍵值以後，將這個值封裝給javaBean的哪個屬性
	-->
    <insert id="addEmp" parameterType="com.mybatis.bean.Employee" useGeneratedKeys="true" keyProperty="id">
        insert into tbl_employee(last_name, gender, email)
        values (#{lastName},#{gender},#{email})
    </insert>
</mapper>

3、測試代碼

package com.mybatis.demo;

import java.io.IOException;
import java.io.InputStream;

import com.mybatis.bean.Employee;
import com.mybatis.dao.EmployeeMapper;
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;

public class MyTest {
    public SqlSessionFactory getSqlSessionFactory() throws IOException {
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        return new SqlSessionFactoryBuilder().build(inputStream);
    }

    @Test
    public void testAdd() throws IOException {
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
        SqlSession openSession = sqlSessionFactory.openSession(true);
        try {
            EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
            Employee employee = new Employee("jetty", "[email protected]", 1);
            mapper.addEmp(employee);
            System.out.println(employee.getId());
        } finally {
            openSession.close();
        }
    }
}

Mybatis學習筆記4 - 獲取自增主鍵的值