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我尝试将 Spring Data jpa 与泛型一起使用，但是当我运行单元测试时会处理相同的异常。这是一个例外：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'tn.moussi.PostRepositorytest': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: tn.moussi.repositories.PostRepository tn.moussi.PostRepositorytest.repository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'postRepository': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:374)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:110)
    at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75)
    at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:313)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:211)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:288)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:284)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: tn.moussi.repositories.PostRepository tn.moussi.PostRepositorytest.repository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'postRepository': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:506)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
    ... 26 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'postRepository': FactoryBean threw exception on object creation; nested exception is java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:149)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:102)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1442)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:248)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:876)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:818)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:735)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478)
    ... 28 more
Caused by: java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1364)
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1300)
    at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:294)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:365)
    at com.sun.proxy.$Proxy22.createQuery(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at com.sun.proxy.$Proxy20.createQuery(Unknown Source)
    at org.springframework.data.jpa.repository.query.SimpleJpaQuery.<init>(SimpleJpaQuery.java:69)
    at org.springframework.data.jpa.repository.query.SimpleJpaQuery.fromQueryAnnotation(SimpleJpaQuery.java:132)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$DeclaredQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:114)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:160)
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:68)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:280)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:148)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.getObject(RepositoryFactoryBeanSupport.java:125)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.getObject(RepositoryFactoryBeanSupport.java:41)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:142)
    ... 36 more
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]
    at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:180)
    at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:110)
    at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:93)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:324)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3291)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3180)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:706)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:562)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:299)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:247)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:248)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:183)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:105)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:168)
    at org.hibernate.internal.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:221)
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:199)
    at org.hibernate.internal.SessionImpl.createQuery(SessionImpl.java:1735)
    at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:291)
    ... 58 more

这是java代码：

导入 java.io.Serializable；

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;


public interface GenericRepository<T,ID extends Serializable> extends JpaRepository<T, ID> {

    @Query("select t from T t where t.title = :TITLE")
    T findByTitle(@Param("TITLE") String title);

}

import org.springframework.stereotype.Repository;

import tn.moussi.entities.Post;

@Repository("postRepository")
public interface PostRepository extends GenericRepository< Post, Integer> {


}

单元测试：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:META-INF/application-context.xml")
public class PostRepositorytest {


    @Autowired
    @Qualifier(value="postRepository")
    PostRepository repository;

    @Test
    public void test() {
        Post post = new Post();
        post.setPostDate(new Date());
        post.setTitle("first post");

        repository.save(post);

        Post dbpost = repository.findByTitle(post.getTitle());
        assertNotNull(dbpost);
        System.out.println(dbpost.getTitle());

    }

}

实体类帖子：

@Entity
@Table(name="POST")
public class Post{

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name="POST_ID")
    Integer postId;

    @Column(name="TITLE")
    String title;
    @Column(name="POST_DATE")
    Date postDate;

    public Integer getPostId() {
        return postId;
    }
    public void setPostId(Integer postId) {
        this.postId = postId;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public Date getPostDate() {
        return postDate;
    }
    public void setPostDate(Date postDate) {
        this.postDate = postDate;
    }
}

应用程序上下文文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd">

<!-- database -->
<jdbc:embedded-database id="datasource" type="H2"></jdbc:embedded-database>

<!--  Entity manager -->
 <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
  <property name="dataSource" ref="datasource"/>
        <property name="persistenceUnitName" value="moussi-tutorial"/>
 </bean>

 <!--  Transaction Manager -->
 <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
  </bean>

 <!--  Jap repositories -->
 <jpa:repositories base-package="tn.moussi"></jpa:repositories>

<context:annotation-config/>
    <context:component-scan base-package="tn.moussi" />

</beans>

persistence.xml 文件：

<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">

  <persistence-unit name="moussi-tutorial" transaction-type="RESOURCE_LOCAL">
     <provider>org.hibernate.ejb.HibernatePersistence</provider>

    <properties>
         <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
         <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
         <property name="hibernate.show_sql" value="true"/>
      </properties>
  </persistence-unit>

</persistence>
4

3 回答 3

1

这不会像您期望的那样工作。虽然具体类继承了该方法并允许我们在运行时找出具体的返回类型，但我们不会（不能）对手动定义的查询进行任何泛型替换。其原因是基本上没有办法确定您是否实际上从查询中引用了泛型类型（阅读：查询中的 T 基本上可以表示任何内容，只需查看查询）。

您可以选择为每种具体类型的 T 引入专用命名查询，例如TypeA.findByTitle,TypeB.findByTitle等等。然后，我们将使用这些来支持继承到具体存储库接口中的方法。此外，您可能希望GenericRepository使用 @NoRepositoryBean 注释接口以防止在组件扫描期间被拾取。阅读参考文档中的详细信息。

于 2013-03-21T11:56:44.020 回答
0

我可能猜想这是因为您的 JPA 提供程序无法在您的 GenericRepository 接口中处理查询：

select t from T t where t.title = :TITLE

为了了解这是否是根本原因 - 尝试在 PostRepository 中引入另一个 findByTitle2 方法来解决显式命名的实体：

@Query("select t from Post t where t.title = :TITLE")
T findByTitle(@Param("TITLE") String title);

请注意，您的堆栈跟踪通过以下报告解决了这个问题：

QuerySyntaxException: T is not mapped [select t from T t where t.title = :TITLE]

我不确定这样的查询参数化select t from T t where t.title = :TITLE是否可能 - 由于 java 中泛型实现的细节，并不总是可以在运行时提取正确的参数化类型信息来决定在应用程序的某个点使用什么类型。

于 2013-03-21T10:35:53.773 回答
0

我不确定这是可能的。问题是T每个接口的通用参数都会不同。在您的@QueryT 是在注释上的 value 元素中静态定义的，select t from T.... 在普通的 JPA 查询中，实体的类型将在查询中指定。如下：

@Query("select t from Book t where t.title = :TITLE")
Book findByTitle(@Param("TITLE") String title);

如果允许扩展接口，Spring Data 需要足够聪明才能T在运行时确定泛型参数的类型（这与泛型背道而驰，因为大多数操作都是编译时的）。然后它需要将此类型替换为@Query注解值元素中静态定义的查询。我没有看到任何证据表明这是可能的。

于 2013-03-21T10:28:26.957 回答