SpringData 和 QueryDSL 服务的通用类实现答案

【问题标题】：Generic class Implementation for a SpringData & QueryDSL ServiceSpringData 和 QueryDSL 服务的通用类实现
【发布时间】：2015-12-14 11:31:46
【问题描述】：

我有一堆服务类，它们具有扩展 JpaRepository 和 QueryDslPredicateExecutor 的存储库。除了它处理的实体之外，服务类中的方法是相同的。我正在尝试创建一个通用的服务类，但我得到一个“资源依赖注入失败；嵌套异常是 org.springframework.beans.factory.NoSuchBeanDefinitionException：没有为依赖找到类型 [pkg.BaseRepository] 的合格 bean：预计至少有 1 个合格的 bean作为此依赖项的自动装配候选者”。

以下是我的课程：

//BaseRepository.java
@NoRepositoryBean
public interface BaseRepository<T> extends JpaRepository<T, Long>, QueryDslPredicateExecutor<T> {}

//RegionRepository.java
@Repository
public interface RegionRepository<Region> extends JpaRepository<Region, Long>, QueryDslPredicateExecutor<Region> {}

//ProvinceRepository.java
@Repository
public interface ProvinceRepository<Province> extends JpaRepository<Province, Long>, QueryDslPredicateExecutor<Province> {}

... 以及更多 XxxRepository 接口

//AbstractBaseService.java
public abstract class AbstractBaseService<T>{
    @Autowired 
    private BaseRepository<T> repository;

    public void add(T entity) {
        System.out.println("Adding entity " + entity.getClass());
    }

    public T retrieve(Long id) {
        System.out.println("Retrieving region with dbId = " + id);
        return repository.findOne(id);
    }

    public List<T> findAll() {
        return repository.findAll();
    }
    ...
    //some other methods

}

//RegionService.java
@Service("regService")
public class RegionService extends AbstractBaseService<Region> {}

//ProvinceService.java
@Service("provService")
public class ProvinceService extends AbstractBaseService<Province> {}


@Controller
public class MyController {

    public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("/spring/application-context.xml");

        MyController controller = new MyController();
        controller.run(context);
    }

    public void run(ApplicationContext context) {       
        RegionService regService =  (RegionService)context.getBean("regService");
        Region reg = regService.retrieve(1L);
    }
}

我的persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
      http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
    version="2.1">

    <persistence-unit name="generics" transaction-type="RESOURCE_LOCAL">      
        <properties>
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.cache.provider_class" value="org.hibernate.cache.HashtableCacheProvider" />
        </properties>
    </persistence-unit>
</persistence>

application-context.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
    http://www.springframework.org/schema/data/jpa 
    http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <!-- Root Context: defines shared resources visible to all other web components -->
    <context:component-scan base-package="com.dreamcorps.gen" />

    <bean id="placeholderConfig"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:spring/db.properties" />
    </bean>

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="database"           value="${jpa.dbVendor}" />
                <property name="databasePlatform"   value="${jpa.dialect}"  />
                <property name="showSql"            value="${jpa.showSql}"  />  
                <property name="generateDdl"        value="false" />
            </bean>
        </property> 
        <property name="persistenceUnitName" value="generics" />    
    </bean>

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
        <!-- access -->
        <property name="driverClass"                value="${jdbc.driver}"/>
        <property name="jdbcUrl"                    value="${jdbc.url}"/>
        <property name="user"                       value="${jdbc.username}"/>
        <property name="password"                   value="${jdbc.password}"/>

        <!-- pool sizing -->
        <property name="initialPoolSize"            value="${c3p0.initialPoolSize}"/>
        <property name="minPoolSize"                value="${c3p0.minPoolSize}"/>
        <property name="maxPoolSize"                value="${c3p0.maxPoolSize}"/>
        <property name="acquireIncrement"           value="${c3p0.acquireIncrement}"/>
        <property name="maxStatements"              value="${c3p0.maxStatements}"/>

    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    </bean>

    <tx:annotation-driven />
    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />

    <jpa:repositories base-package="com.dreamcorps.gen" />

</beans>

下面是 MyController 运行时的错误日志。

Dec 12, 2015 12:49:35 AM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {5.0.3.Final}
Dec 12, 2015 12:49:35 AM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
Dec 12, 2015 12:49:35 AM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
Dec 12, 2015 12:49:36 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {5.0.0.Final}
Dec 12, 2015 12:49:36 AM org.hibernate.engine.jdbc.connections.internal.ConnectionProviderInitiator initiateService
WARN: HHH000181: No appropriate connection provider encountered, assuming application will be supplying connections
Dec 12, 2015 12:49:36 AM org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator initiateService
WARN: HHH000342: Could not obtain connection to query metadata : The application must supply JDBC connections
Dec 12, 2015 12:49:36 AM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
Dec 12, 2015 12:49:36 AM org.hibernate.engine.jdbc.env.internal.LobCreatorBuilderImpl makeLobCreatorBuilder
INFO: HHH000422: Disabling contextual LOB creation as connection was null
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'regionServiceImpl': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not an managed type: class java.lang.Object
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:311)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1214)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:305)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:301)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:835)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
    at com.dreamcorps.sample.controller.MyController.main(MyController.java:18)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'baseRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not an managed type: class java.lang.Object
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:305)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:301)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1192)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1116)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:508)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:486)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:615)
    at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:169)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:308)
    ... 13 more
Caused by: java.lang.IllegalArgumentException: Not an managed type: class java.lang.Object
    at org.hibernate.jpa.internal.metamodel.MetamodelImpl.managedType(MetamodelImpl.java:210)
    at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.<init>(JpaMetamodelEntityInformation.java:68)
    at org.springframework.data.jpa.repository.support.JpaEntityInformationSupport.getEntityInformation(JpaEntityInformationSupport.java:67)
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getEntityInformation(JpaRepositoryFactory.java:142)
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:89)
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getTargetRepository(JpaRepositoryFactory.java:71)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:185)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.initAndReturn(RepositoryFactoryBeanSupport.java:251)
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:237)
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:92)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
    ... 28 more


Is there a way to make the AbstractBaseService work as I envision above so that I don't have to create the one Service class with the same implementation as AbstractBaseService for each of my entities (Region, Province, User, Vehicle.... etc)?

任何帮助将不胜感激。

提前致谢，马里奥

【问题讨论】：

标签： java spring generics querydsl

【解决方案1】：

//RegionRepository.java
@Repository
public interface RegionRepository<Region> extends JpaRepository<Region, Long>, QueryDslPredicateExecutor<Region> {}
                                  ^^^^^^ Here you are actually making a new Type Variable, which is bounded to Object.

您正在创建新的类型变量，这实际上隐藏了您正在为其创建存储库的类名称。

【讨论】：

鲁本，感谢您的快速回复/评论。我此时实际上正在与仿制药作斗争。你能指导或给我额外的建议，告诉我应该用 BaseRepository 或 Region/Province 存储库做什么。
只有BaseRepository<T>应该有类型参数，RegionRepository implements BaseRepository<Region>应该只填写接口的空白，不能声明额外的类型参数。

【解决方案2】：

我终于能够让我原来的帖子工作了。缺少的是 BaseRepository.java 接口上的 @NoRepositoryBean 注释和 RegionRepository/ProvinceRepository 接口上的 @Repository 注释，如上所述。

【讨论】：

请不要用答案编辑您的问题。现在我们不再看到最初的问题了。相反，保持问题不变并在答案中写下解决方案。