Mybatis实现增、删、改操作时返回主键

需求:查询出刚刚插入(删除/修改)的记录的详细信息

　　1、xxxMapper接口

public interface EmployeeMapper {
    // 添加操作
    public int insertEmployee(Employee employee);

    // 根据ID查询出一条记录
    public Employee queryEmployeeByEmployeeId(Integer employeeId);
}

　　2、xxxMapper.xml

<mapper namespace="com.mybatis.dao.EmployeeMapper">
	// 插入一条记录
	// useGeneratedKeys:默认值是true,但是还是建议写上
	// keyProperty:将刚刚插入的记录的主键使用传入的Employee对象中的employeeId属性接收
    <insert id="insertEmployee" useGeneratedKeys="true" keyProperty="employeeId">
        INSERT INTO employee VALUES (null,#{employeeName},#{employeePassword},#{employeeAge},#{departmentId})
    </insert>
	// 根据employeeId查询Employee对象
    <select id="queryEmployeeByEmployeeId" resultType="com.mybatis.entity.Employee">
        SELECT EMPLOYEE_ID,EMPLOYEE_NAME,EMPLOYEE_PASSWORD,EMPLOYEE_AGE,DEPARTMENT_ID FROM employee
        WHERE EMPLOYEE_ID=#{employeeId}
    </select>
</mapper>　

　　3、测试类

@Test
    public void test01() throws IOException {
        SqlSession session = TestMybatis.openSession();
        EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);
        Employee employee = new Employee();
        employee.setEmployeeName("田七");
        employee.setEmployeeAge("27");
        employee.setEmployeePassword("4456");
        employee.setDepartmentId(4);
        // 这里返回的是影响的行数
        int i = mapper.insertEmployee(employee);
        // 根据插入的id,查询出刚刚插入的记录,因为我们将插入的主键封装进了Employee对象的employeeId属性中
        Employee e = mapper.queryEmployeeByEmployeeId(employee.getEmployeeId());
        System.out.println(e);
    }

　　4、测试结果

Employee{employeeId=9, employeeName='田七', employeePassword='4456', employeeAge='27', departmentId=4}