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Spring Data JPA 指南——整理自官方参考文档

2016-09-21 14:10 531 查看
基本使用方法

自定义Repository

定义查询方法
查询方法建立

特殊参数处理

限制查询结果数量

流式查询结果

异步查询结果

关键字

使用 Query
基本用法

使用 LIKE 表达式

使用原生SQL

原生SQL分页

使用 Sort 和 JpaSort

使用已命名参数

修改查询

基本使用方法

继承接口并声明查询方法

interface PersonRepository extends Repository<Person, Long> {
List<Person> findByLastname(String lastname);
}


Autowired注入

public class SomeClient {

@Autowired
private PersonRepository repository;

public void doSomething() {
List<Person> persons = repository.findByLastname("Matthews");
}
}


自定义Repository

选择性暴露CURD方法

@NoRepositoryBean
interface MyBaseRepository<T, ID extends Serializable> extends Repository<T, ID> {

T findOne(ID id);

T save(T entity);
}

interface UserRepository extends MyBaseRepository<User, Long> {
User findByEmailAddress(EmailAddress emailAddress);
}


使用特定模块接口定义Repository

interface MyRepository extends JpaRepository<User, Long> { }

@NoRepositoryBean
interface MyBaseRepository<T, ID extends Serializable> extends JpaRepository<T, ID> {
…
}

interface UserRepository extends MyBaseRepository<User, Long> {
…
}


注意：中间层repository接口要使用注解@NoRepositoryBean，以确保Spring Data不会在运行时对其实例化。

定义查询方法

查询方法建立

distinct flag

ignoring case

order by

public interface PersonRepository extends Repository<User, Long> {

List<Person> findByEmailAddressAndLastname(EmailAddress emailAddress, String lastname);

// Enables the distinct flag for the query
List<Person> findDistinctPeopleByLastnameOrFirstname(String lastname, String firstname);
List<Person> findPeopleDistinctByLastnameOrFirstname(String lastname, String firstname);

// Enabling ignoring case for an individual property
List<Person> findByLastnameIgnoreCase(String lastname);
// Enabling ignoring case for all suitable properties
List<Person> findByLastnameAndFirstnameAllIgnoreCase(String lastname, String firstname);

// Enabling static ORDER BY for a query
List<Person> findByLastnameOrderByFirstnameAsc(String lastname);
List<Person> findByLastnameOrderByFirstnameDesc(String lastname);
}


为了消除不确定性，可以在方法名内使用下划线“_”手动定义隔断点。

List<Person> findByAddress_ZipCode(ZipCode zipCode);


特殊参数处理

Page<User> findByLastname(String lastname, Pageable pageable);

Slice<User> findByLastname(String lastname, Pageable pageable);

List<User> findByLastname(String lastname, Sort sort);

List<User> findByLastname(String lastname, Pageable pageable);


限制查询结果数量

User findFirstByOrderByLastnameAsc();

User findTopByOrderByAgeDesc();

Page<User> queryFirst10ByLastname(String lastname, Pageable pageable);

Slice<User> findTop3ByLastname(String lastname, Pageable pageable);

List<User> findFirst10ByLastname(String lastname, Sort sort);

List<User> findTop10ByLastname(String lastname, Pageable pageable);


流式查询结果

@Query("select u from User u")
Stream<User> findAllByCustomQueryAndStream();

Stream<User> readAllByFirstnameNotNull();

@Query("select u from User u")
Stream<User> streamAllPaged(Pageable pageable);


流在使用结束后需要关闭以释放资源，可以用 close() 方法手动将其关闭或者使用 try-with-resources 块。

try-with-resources 块

try (Stream<User> stream = repository.findAllByCustomQueryAndStream()) {
stream.forEach(…);
}


异步查询结果

使用 
java.util.concurrent.Future
作为返回类型

使用 Java 8 
java.util.concurrent.CompletableFuture
作为返回类型

使用 
org.springframework.util.concurrent.ListenableFuture
作为返回类型

@Async
Future<User> findByFirstname(String firstname);

@Async
CompletableFuture<User> findOneByFirstname(String firstname);

@Async
ListenableFuture<User> findOneByLastname(String lastname);


关键字

KeywordSampleJPQL snippet
AndfindByLastnameAndFirstname… where x.lastname = ?1 and x.firstname = ?2
OrfindByLastnameOrFirstname… where x.lastname = ?1 or x.firstname = ?2
Is,EqualsfindByFirstname,findByFirstnameIs,findByFirstnameEquals… where x.firstname = ?1
BetweenfindByStartDateBetween… where x.startDate between ?1 and ?2
LessThanfindByAgeLessThan… where x.age < ?1
LessThanEqualfindByAgeLessThanEqual… where x.age <= ?1
GreaterThanfindByAgeGreaterThan… where x.age > ?1
GreaterThanEqualfindByAgeGreaterThanEqual… where x.age >= ?1
AfterfindByStartDateAfter… where x.startDate > ?1
BeforefindByStartDateBefore… where x.startDate < ?1
IsNullfindByAgeIsNull… where x.age is null
IsNotNull,NotNullfindByAge(Is)NotNull… where x.age not null
LikefindByFirstnameLike… where x.firstname like ?1
NotLikefindByFirstnameNotLike… where x.firstname not like ?1
StartingWithfindByFirstnameStartingWith… where x.firstname like ?1(parameter bound with appended %)
EndingWithfindByFirstnameEndingWith… where x.firstname like ?1(parameter bound with prepended %)
ContainingfindByFirstnameContaining… where x.firstname like ?1(parameter bound wrapped in %)
OrderByfindByAgeOrderByLastnameDesc… where x.age = ?1 order by x.lastname desc
NotfindByLastnameNot… where x.lastname <> ?1
InfindByAgeIn(Collection ages)… where x.age in ?1
NotInfindByAgeNotIn(Collection age)… where x.age not in ?1
TruefindByActiveTrue()… where x.active = true
FalsefindByActiveFalse()… where x.active = false
IgnoreCasefindByFirstnameIgnoreCase… where UPPER(x.firstame) = UPPER(?1)

使用 @Query

基本用法

public interface UserRepository extends JpaRepository<User, Long> {

@Query("select u from User u where u.emailAddress = ?1")
User findByEmailAddress(String emailAddress);
}


使用 LIKE 表达式

public interface UserRepository extends JpaRepository<User, Long> {

@Query("select u from User u where u.firstname like %?1")
List<User> findByFirstnameEndsWith(String firstname);
}


使用原生SQL

public interface UserRepository extends JpaRepository<User, Long> {

@Query(value = "SELECT * FROM USERS WHERE EMAIL_ADDRESS = ?1", nativeQuery = true)
User findByEmailAddress(String emailAddress);
}


原生SQL分页

public interface UserRepository extends JpaRepository<User, Long> {

@Query(value = "SELECT * FROM USERS WHERE LASTNAME = ?1",
countQuery = "SELECT count(*) FROM USERS WHERE LASTNAME = ?1",
nativeQuery = true)
Page<User> findByLastname(String lastname, Pageable pageable);
}


使用 Sort 和 JpaSort

public interface UserRepository extends JpaRepository<User, Long> {

@Query("select u from User u where u.lastname like ?1%")
List<User> findByAndSort(String lastname, Sort sort);

@Query("select u.id, LENGTH(u.firstname) as fn_len from User u where u.lastname like ?1%")
List<Object[]> findByAsArrayAndSort(String lastname, Sort sort);
}

repo.findByAndSort("lannister", new Sort("firstname"));
repo.findByAndSort("stark", new Sort("LENGTH(firstname)"));
repo.findByAndSort("targaryen", JpaSort.unsafe("LENGTH(firstname)"));
repo.findByAsArrayAndSort("bolton", new Sort("fn_len"));


使用已命名参数

public interface UserRepository extends JpaRepository<User, Long> {

@Query("select u from User u where u.firstname = :firstname or u.lastname = :lastname")
User findByLastnameOrFirstname(@Param("lastname") String lastname,
@Param("firstname") String firstname);
}


修改查询

@Modifying
@Query("update User u set u.firstname = ?1 where u.lastname = ?2")
int setFixedFirstnameFor(String firstname, String lastname);
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标签：  spring SpringData JPA
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