基本使用方法

繼承介面並宣告查詢方法

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

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Autowired注入

public class SomeClient {

  @Autowired
  private PersonRepository repository;

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

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自定義Repository

選擇性暴露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);
}
 

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使用特定模組介面定義Repository

interface MyRepository extends JpaRepository<User, Long> { }

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

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

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  注意：中間層repository介面要使用註解@NoRepositoryBean，以確保Spring Data不會在執行時對其例項化。

定義查詢方法

查詢方法建立

1. distinct flag
2. ignoring case
3. 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);
}

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  為了消除不確定性，可以在方法名內使用下劃線“_”手動定義隔斷點。
  List<Person> findByAddress_ZipCode(ZipCode zipCode);

特殊引數處理

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);

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限制查詢結果數量

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);

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流式查詢結果

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

Stream<User> readAllByFirstnameNotNull();

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

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    流在使用結束後需要關閉以釋放資源，可以用 close() 方法手動將其關閉或者使用 try-with-resources 塊。

• try-with-resources 塊

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

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非同步查詢結果

1. 使用 java.util.concurrent.Future 作為返回型別
2. 使用 a Java 8 java.util.concurrent.CompletableFuture 作為返回型別
3. 使用 a org.springframework.util.concurrent.ListenableFuture 作為返回型別

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

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

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

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關鍵字

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);
}

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使用 LIKE 表示式

public interface UserRepository extends JpaRepository<User, Long> {

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

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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);
}

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原生SQL分頁

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);
}

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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"));              

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使用已命名引數

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);
}

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修改查詢

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

    查詢部分記錄   -----top---first Distinct
    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);

     Java 8 Stream<T>---
    @Query("select u from User u")
    Stream<User> findAllByCustomQueryAndStream();

    Stream<User> readAllByFirstnameNotNull();

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

    非同步查詢結果
-Use java.util.concurrent.Future as return type.
    @Async
    Future<User> findByFirstname(String firstname);
-Use a Java 8 java.util.concurrent.CompletableFuture as return type.
    @Async
    CompletableFuture<User> findOneByFirstname(String firstname);
-Use a org.springframework.util.concurrent.ListenableFuture as return type
    @Async
    ListenableFuture<User> findOneByLastname(String lastname);