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JPA-JpaRepository方法命名语法说明

程序员文章站 2022-06-26 15:35:08
目录前言jpa的语法分为如下5种:1、count相关,返回值为int 或 long2、exists相关,返回值只能是 boolean3、find相关,返回值是数组list4、fi...

前言

梳理了一遍jpa的方法命名语法,记录一下,以便后续备查。

注:本文不介绍jpl语法,版本为spring-data-jpa-2.3.0.release。

假设实体类名为 aaa,且定义如下:

import lombok.data;
import javax.persistence.entity;
import javax.persistence.id;
@entity
@data
public class aaa {
    @id
    private long id;
    private long restid;
    private int dishhour;
    private int num;
}

对应的仓储层接口定义:

import org.springframework.data.jpa.repository.jparepository;
import org.springframework.stereotype.repository;
import javax.transaction.transactional;
import java.util.list;
@repository
public interface aaarepository extends jparepository<aaa, long> {
    int countbydishhourandrestid(int hour, long restid);
    boolean existsbydishhourandrestid(int hour, long restid);
    list<aaa> findbydishhourandrestid(int hour, long restid);
    aaa findtopbydishhourandrestid(int hour, long restid);
    @transactional
    int deletebydishhourandrestid(int hour, long restid);
}

jpa的语法分为如下5种:

1、count相关,返回值为int 或 long

int countbydishhourandrestid(int hour, long restid);
int countaaabydishhourandrestid(int hour, long restid);
int countaaasbydishhourandrestid(int hour, long restid);
int countallbydishhourandrestid(int hour, long restid);

上面这4个方法是一样的,对应的sql如下:

select count(id) from aaa where dishhour=? and restid=?

下面这种定义,没有意义,知晓一下就好:

int countdistinctbydishhourandrestid(int hour, long restid);

对应sql如下,如果表中有主键,功能跟countby是一致的,浪费性能:

select distinct count(distinct id) from aaa where dishhour=? and restid=?

2、exists相关,返回值只能是 boolean

boolean existsbydishhourandrestid(int hour, long restid);
boolean existsaaabydishhourandrestid(int hour, long restid);
boolean existsaaasbydishhourandrestid(int hour, long restid);
boolean existsallbydishhourandrestid(int hour, long restid);

上面这4个方法是一样的,对应的sql如下:

select id from aaa where dishhour=? and restid=? limit 1

下面这种定义,没有意义,知晓一下就好:

boolean existsdistinctbydishhourandrestid(int hour, long restid);

对应sql如下,功能跟existsby是一致的,多余:

select distinct id from aaa where dishhour=? and restid=? limit 1

3、find相关,返回值是数组list<aaa>

list<aaa> findbydishhourandrestid(int hour, long restid);
list<aaa> findaaabydishhourandrestid(int hour, long restid);
list<aaa> findaaasbydishhourandrestid(int hour, long restid);
list<aaa> findallbydishhourandrestid(int hour, long restid);
list<aaa> getbydishhourandrestid(int hour, long restid);
list<aaa> getaaabydishhourandrestid(int hour, long restid);
list<aaa> getaaasbydishhourandrestid(int hour, long restid);
list<aaa> getallbydishhourandrestid(int hour, long restid);
list<aaa> querybydishhourandrestid(int hour, long restid);
list<aaa> queryaaabydishhourandrestid(int hour, long restid);
list<aaa> queryaaasbydishhourandrestid(int hour, long restid);
list<aaa> queryallbydishhourandrestid(int hour, long restid);
list<aaa> readbydishhourandrestid(int hour, long restid);
list<aaa> readaaabydishhourandrestid(int hour, long restid);
list<aaa> readaaasbydishhourandrestid(int hour, long restid);
list<aaa> readallbydishhourandrestid(int hour, long restid);
list<aaa> streambydishhourandrestid(int hour, long restid);
list<aaa> streamaaabydishhourandrestid(int hour, long restid);
list<aaa> streamaaasbydishhourandrestid(int hour, long restid);
list<aaa> streamallbydishhourandrestid(int hour, long restid);

上面这20个方法是一样的,对应的sql如下:

select id,dishhour,num,restid from aaa where dishhour=? and restid=?

下面这种定义,没有意义,知晓一下就好:

list<aaa> finddistinctbydishhourandrestid(int hour, long restid);

对应sql如下,如果表中有主键,功能跟findby是一致的,多余:

select distinct id,dishhour,num,restid from aaa where dishhour=? and restid=?

4、findfirst相关,返回值是aaa

aaa findfirstbydishhourandrestid(int hour, long restid);
aaa findtopbydishhourandrestid(int a, long b);
aaa getfirstbydishhourandrestid(int hour, long restid);
aaa gettopbydishhourandrestid(int a, long b);
aaa queryfirstbydishhourandrestid(int hour, long restid);
aaa querytopbydishhourandrestid(int a, long b);
aaa readfirstbydishhourandrestid(int hour, long restid);
aaa readtopbydishhourandrestid(int a, long b);
aaa streamfirstbydishhourandrestid(int hour, long restid);
aaa streamtopbydishhourandrestid(int a, long b);

上面这10个方法是一样的,对应的sql如下:

select id,dishhour,num,restid from aaa where dishhour=? and restid=? limit 1

注:返回值也可以改成list<aaa>,但是sql不变,返回的数组也只有一条数据

下面这种定义,没有意义,知晓一下就好:

list<aaa> finddistinctfirstbydishhourandrestid(int hour, long restid);

对应sql如下,如果表中有主键,功能跟countby是一致的,多余:

select distinct id,dishhour,num,restid from aaa where dishhour=? and restid=? limit 1

5、delete相关,返回值是int,删除行数

@transactional
int deleteaaabydishhourandrestid(int a, long b);
@transactional
int deleteaaasbydishhourandrestid(int a, long b);
@transactional
int deleteallbydishhourandrestid(int a, long b);
@transactional
int deletebydishhourandrestid(int a, long b);
@transactional
int removeaaabydishhourandrestid(int a, long b);
@transactional
int removeaaasbydishhourandrestid(int a, long b);
@transactional
int removeallbydishhourandrestid(int a, long b);
@transactional
int removebydishhourandrestid(int a, long b);

上面这8个方法是一样的,对应有2条sql,如下:

select id,dishhour,num,restid from aaa where dishhour=? and restid=?
delete from aaa where id=?

注:先select查找主键,再进行删除,所以必须在方法前加注解transactional,提供事务,否则会抛异常。

下面这种定义,没有意义,知晓一下就好:

int deletedistinctbydishhourandrestid(int hour, long restid);

对应sql如下,如果表中有主键,功能跟deleteby是一致的,多余:

select distinct id,dishhour,num,restid from aaa where dishhour=? and restid=?

注1:方法by后面的语法,可以参考下图,或官方文档

JPA-JpaRepository方法命名语法说明

注2:jpa query注解问题:

sql里可以用 #{#entityname} 占位符,替代手写表名,如:

@query(value = "select * from #{#entityname} where 1=2", nativequery = true)
aaa selectxxx();

insert、update、delete这3种dml操作,返回值只能是void、int、long,且必须增加2个注解,例如:

// 返回值不是void、int、long,报错:
// modifying queries can only use void or int/integer as return type!
// 不加 transactional 报错: 
// javax.persistence.transactionrequiredexception: executing an update/delete query
@transactional
// 不加modifing 报错:
// can not issue data manipulation statements with executequery().
@modifying
@query(value = "update #{#entityname} set num=num+1 where id=6", nativequery = true)
int doupdate();

注3:jpa原生方法列表:

list<t> findall();
list<t> findall(sort var1);
list<t> findallbyid(iterable<id> var1);
<s extends t> list<s> saveall(iterable<s> var1);
void flush();
<s extends t> s saveandflush(s var1);
void deleteinbatch(iterable<t> var1);
void deleteallinbatch();
t getone(id var1);
<s extends t> list<s> findall(example<s> var1);
<s extends t> list<s> findall(example<s> var1, sort var2);

以上为个人经验,希望能给大家一个参考,也希望大家多多支持。