延续上一篇增删改查，在添加的时候使用的是数据库的自增主键，如果换成oracle这种没有自增主键的就无法实现，并且保存完成之后，在程序中是获取不到对象id的。我们打印保存后的对象如下：
1.未配置主键自增
@Test
public void testMybatisAdd() {
//测试添加
SqlSessionFactory sqlSessionFactory = null;
SqlSession sqlSession = null;
try {
sqlSessionFactory = getSqlSessionFactory();
//openSession可以添加参数，无参数表示不会自动提交，需要手动提交
sqlSession = sqlSessionFactory.openSession();
// sqlSession = sqlSessionFactory.openSession(true);
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
Employee employee = new Employee();
//数据库设置id自增
employee.setLastName("huanan");
employee.setEmail("tang_man@sina.com");
employee.setGender("2");
mapper.addEmployee(employee);
System.out.println(employee);
sqlSession.commit();
} catch (IOException e) {
e.printStackTrace();
} finally {
sqlSession.close();
}
}
DEBUG - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@184f6be2]
DEBUG - ==> Preparing: insert into mybatis_employee (last_name,email,gender) values (?,?,?);
DEBUG - ==> Parameters: huanan(String), tang_man@sina.com(String), 2(String)
Employee [id=null, lastName=huanan, email=tang_man@sina.com, gender=2]
这里打印的id=null，mybatis可以通过配置，自动生成主键
2.配置主键自增
在insert 标签中添加两个值
useGeneratedKeys=”true”表示使用自增主键
keyProperty=”id”表示id为自增主键
<!-- 插入方法 -->
<insert id="addEmployee" parameterType="org.mybatis.crud.Employee" useGeneratedKeys="true" keyProperty="id">
insert into mybatis_employee
(last_name,email,gender)
values
(#{lastName},#{email},#{gender});
</insert>
再次测试添加方法，可以获取到主键的值id=7
DEBUG - ooo Using Connection [com.mysql.jdbc.JDBC4Connection@1f7030a6]
DEBUG - ==> Preparing: insert into mybatis_employee (last_name,email,gender) values (?,?,?);
DEBUG - ==> Parameters: hussanan(String), tang_@qq.com(String), 2(String)
Employee [id=7, lastName=hussanan, email=tang_@qq.com, gender=2]
3.不存在自增主键数据库如何配置
<!-- 插入方法oracle -->
<insert id="addEmployeeo">
<!--
keyProperty=id需要赋值主键的属性，一般都是id
order=before表示在插入之前执行该查询
resultType=Integer表示返回值为integer类型
-->
<selectKey keyProperty="id" order="BEFORE" resultType="Integer">
select employees_seq.nextval from dual;
</selectKey>
insert into mybatis_employee
(id,last_name,email,gender)
values
(#{id},#{lastName},#{email},#{gender});
</insert>