Spring Data JPA 指南参考文档

缺乏、安全感 2024-02-19 00:15 63阅读 0赞

## 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 ###

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);
    }

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 ###

1.  使用 `java.util.concurrent.Future` 作为返回类型
2.  使用 Java 8 `java.util.concurrent.CompletableFuture` 作为返回类型
3.  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 ##

<table> 
 <thead> 
  <tr> 
   <th>Keyword</th> 
   <th>Sample</th> 
   <th>JPQL snippet</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>And</td> 
   <td>findByLastnameAndFirstname</td> 
   <td>… where x.lastname = ?1 and x.firstname = ?2</td> 
  </tr> 
  <tr> 
   <td>Or</td> 
   <td>findByLastnameOrFirstname</td> 
   <td>… where x.lastname = ?1 or x.firstname = ?2</td> 
  </tr> 
  <tr> 
   <td>Is,Equals</td> 
   <td>findByFirstname,findByFirstnameIs,findByFirstnameEquals</td> 
   <td>… where x.firstname = ?1</td> 
  </tr> 
  <tr> 
   <td>Between</td> 
   <td>findByStartDateBetween</td> 
   <td>… where x.startDate between ?1 and ?2</td> 
  </tr> 
  <tr> 
   <td>LessThan</td> 
   <td>findByAgeLessThan</td> 
   <td>… where x.age &lt; ?1</td> 
  </tr> 
  <tr> 
   <td>LessThanEqual</td> 
   <td>findByAgeLessThanEqual</td> 
   <td>… where x.age &lt;= ?1</td> 
  </tr> 
  <tr> 
   <td>GreaterThan</td> 
   <td>findByAgeGreaterThan</td> 
   <td>… where x.age &gt; ?1</td> 
  </tr> 
  <tr> 
   <td>GreaterThanEqual</td> 
   <td>findByAgeGreaterThanEqual</td> 
   <td>… where x.age &gt;= ?1</td> 
  </tr> 
  <tr> 
   <td>After</td> 
   <td>findByStartDateAfter</td> 
   <td>… where x.startDate &gt; ?1</td> 
  </tr> 
  <tr> 
   <td>Before</td> 
   <td>findByStartDateBefore</td> 
   <td>… where x.startDate &lt; ?1</td> 
  </tr> 
  <tr> 
   <td>IsNull</td> 
   <td>findByAgeIsNull</td> 
   <td>… where x.age is null</td> 
  </tr> 
  <tr> 
   <td>IsNotNull,NotNull</td> 
   <td>findByAge(Is)NotNull</td> 
   <td>… where x.age not null</td> 
  </tr> 
  <tr> 
   <td>Like</td> 
   <td>findByFirstnameLike</td> 
   <td>… where x.firstname like ?1</td> 
  </tr> 
  <tr> 
   <td>NotLike</td> 
   <td>findByFirstnameNotLike</td> 
   <td>… where x.firstname not like ?1</td> 
  </tr> 
  <tr> 
   <td>StartingWith</td> 
   <td>findByFirstnameStartingWith</td> 
   <td>… where x.firstname like ?1(parameter bound with appended %)</td> 
  </tr> 
  <tr> 
   <td>EndingWith</td> 
   <td>findByFirstnameEndingWith</td> 
   <td>… where x.firstname like ?1(parameter bound with prepended %)</td> 
  </tr> 
  <tr> 
   <td>Containing</td> 
   <td>findByFirstnameContaining</td> 
   <td>… where x.firstname like ?1(parameter bound wrapped in %)</td> 
  </tr> 
  <tr> 
   <td>OrderBy</td> 
   <td>findByAgeOrderByLastnameDesc</td> 
   <td>… where x.age = ?1 order by x.lastname desc</td> 
  </tr> 
  <tr> 
   <td>Not</td> 
   <td>findByLastnameNot</td> 
   <td>… where x.lastname &lt;&gt; ?1</td> 
  </tr> 
  <tr> 
   <td>In</td> 
   <td>findByAgeIn(Collection&lt;Age&gt; ages)</td> 
   <td>… where x.age in ?1</td> 
  </tr> 
  <tr> 
   <td>NotIn</td> 
   <td>findByAgeNotIn(Collection&lt;Age&gt; age)</td> 
   <td>… where x.age not in ?1</td> 
  </tr> 
  <tr> 
   <td>True</td> 
   <td>findByActiveTrue()</td> 
   <td>… where x.active = true</td> 
  </tr> 
  <tr> 
   <td>False</td> 
   <td>findByActiveFalse()</td> 
   <td>… where x.active = false</td> 
  </tr> 
  <tr> 
   <td>IgnoreCase</td> 
   <td>findByFirstnameIgnoreCase</td> 
   <td>… where UPPER(x.firstame) = UPPER(?1)</td> 
  </tr> 
 </tbody> 
</table>

## 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);