Springdata JPA(2.0.6版本)中相似但不同的东西的方法，findById和getOne，findOneById

我就是我 2022-03-15 04:42 410阅读 0赞

# findById、getOne和findOneById的区别 #

**代码示例**

@GetMapping("/getOne")
    	public ResultBean getOne(Long id) {
    		return ResultBean.ok(stu2Service.getOne(id));
    	}

@GetMapping("/findById")
    	public ResultBean findById(Long id) {
    		return ResultBean.ok(stu2Service.findById(id));
    	}

@GetMapping("/findOneById")
    	public ResultBean findOneById(Long id) {
    		return ResultBean.ok(stu2Service.findOneById(id));
    	}

**总结 不同点**

1.  返回对象不同

public Optional<T> findById(ID id)；	返回的是Optional对象，通过.get()可获取到对象
    public T getOne(ID id)；	不是直接返回的对象，但此方法可以获取对象的相关属性值
    Stu2 findOneById(Long id);	根据命名规则中自定义实现，可直接返回到对象

1.  对空值异常的处理不同,此处模拟的是如果Id在数据库中不存在时的异常

findById
            	No value present] with root cause

getOne
     	Unable to find com.aust.first.entity.Stu2 with id 20

findOneById，没有异常出现

1.  SQL语句不同

findById
            	SELECT
    	stu2x0_.id_ AS id_1_1_0_,
    	stu2x0_.admission_time AS admissio2_1_0_,
    	stu2x0_.age_ AS age_3_1_0_,
    	stu2x0_.created_by AS created_4_1_0_,
    	stu2x0_.hobbies_ AS hobbies_5_1_0_,
    	stu2x0_.name_ AS name_6_1_0_,
    	stu2x0_.phone_ AS phone_7_1_0_,
    	stu2x0_.sid_ AS sid_8_1_0_,
    	stu2x0_.summary_ AS summary_9_1_0_
    FROM
    	ls_stu2 stu2x0_
    WHERE
    	stu2x0_.id_ =?

getOne        	
    SELECT
    	stu2x0_.id_ AS id_1_1_0_,
    	stu2x0_.admission_time AS admissio2_1_0_,
    	stu2x0_.age_ AS age_3_1_0_,
    	stu2x0_.created_by AS created_4_1_0_,
    	stu2x0_.hobbies_ AS hobbies_5_1_0_,
    	stu2x0_.name_ AS name_6_1_0_,
    	stu2x0_.phone_ AS phone_7_1_0_,
    	stu2x0_.sid_ AS sid_8_1_0_,
    	stu2x0_.summary_ AS summary_9_1_0_
    FROM
    	ls_stu2 stu2x0_
    WHERE
    	stu2x0_.id_ =?

findOneById        	
    SELECT
    	stu2x0_.id_ AS id_1_1_,
    	stu2x0_.admission_time AS admissio2_1_,
    	stu2x0_.age_ AS age_3_1_,
    	stu2x0_.created_by AS created_4_1_,
    	stu2x0_.hobbies_ AS hobbies_5_1_,
    	stu2x0_.name_ AS name_6_1_,
    	stu2x0_.phone_ AS phone_7_1_,
    	stu2x0_.sid_ AS sid_8_1_,
    	stu2x0_.summary_ AS summary_9_1_
    FROM
    	ls_stu2 stu2x0_
    WHERE
    	stu2x0_.id_ =?

不是很高大上的东西，自己的学习记录而已……