java - NullPointerException：Spring 配置错误或 Kundera JPA 错误

Question

我正在尝试编写一个简单的 Spring 应用程序，但无法让 Spring 存储库正常工作。我得到一个NullPointerExceptionat com.impetus.kundera.query.KunderaQuery.initEntityClass(KunderaQuery.java:390)。

该异常最终是由collectionRepository.findAll().

完整的堆栈跟踪：

java.lang.NullPointerException
    at com.impetus.kundera.query.KunderaQuery.initEntityClass(KunderaQuery.java:390)
    at com.impetus.kundera.query.KunderaQuery.postParsingInit(KunderaQuery.java:353)
    at com.impetus.kundera.query.QueryResolver.getQueryImplementation(QueryResolver.java:80)
    at com.impetus.kundera.persistence.PersistenceDelegator.getQueryInstance(PersistenceDelegator.java:557)
    at com.impetus.kundera.persistence.PersistenceDelegator.createQuery(PersistenceDelegator.java:527)
    at com.impetus.kundera.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:379)
    at com.impetus.kundera.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:717)
    at com.impetus.kundera.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:704)
    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:606)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:241)
    at com.sun.proxy.$Proxy33.createQuery(Unknown Source)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.getQuery(SimpleJpaRepository.java:471)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:264)
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findAll(SimpleJpaRepository.java:60)
    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:606)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:358)
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:343)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:105)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
    at com.sun.proxy.$Proxy35.findAll(Unknown Source)
    at com.example.spring.controller.CollectionController.listCollections(CollectionController.java:29)
    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:606)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:175)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:446)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:434)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

我已经尽可能地对其进行了调试，并且有一些值得关注的原因。回到EntityManagerImpl 第 704 行，将CriteriaQueryTranslator转换CriteriaQuery为SELECT FROM CollectionEntity null。

这个查询显然有问题。因此，深入研究该CriteriaQueryTranslator.translate方法（第 122 行）：

builder.appendAlias(from.getAlias() != null ? from.getAlias() : select.getAlias());

return ，因此被from.getAlias()附加到构建器（也是）。这就是导致奇怪的 JPQL 语法的原因。nullselect.getAlias()nullalias

那么这是昆德拉中的一个错误还是我有一些 Spring 配置错误？

控制器中的collectionRepository.findAll()是产生此错误的原因。

这是我所有的配置和主题 java 文件：

集合控制器：

import com.example.spring.hibernate.CollectionEntity;
import com.example.spring.repositories.CollectionRepository;
import com.example.spring.services.CollectionService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.annotation.Resource;

@Controller
public class CollectionController {

    @Autowired
    private CollectionRepository collectionRepository;

    @RequestMapping(value="/collections", method= RequestMethod.GET)
    public String listCollections(ModelMap model) {
        model.addAttribute("collection", new CollectionEntity());

        // THE ERROR HAPPENS HERE (collectionRepository.findAll())
        model.addAttribute("collections", collectionRepository.findAll());
        return "collections";
    }
}

收藏库：

import com.example.spring.hibernate.CollectionEntity;
import org.springframework.data.jpa.repository.JpaRepository;

public interface CollectionRepository extends JpaRepository<CollectionEntity, Long> {
}

收藏实体：

import javax.persistence.*;
import java.util.Date;

@Entity(name="collection")
@Table(name = "collection", schema = "", catalog = "mydb")
public class CollectionEntity {

    @Id
    @Column(name = "collection_id")
    private int collectionId;

    @Basic
    @Column(name = "collection_name")
    private String collectionName;

    @ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinColumn(name = "collection_type_id")
    private CollectionTypeEntity collectionType;

    @Column(name = "active")
    private boolean active;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "created_at")
    private Date createdDate;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "updated_at")
    private Date updatedDate;

    public Date getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(Date createdDate) {
        this.createdDate = createdDate;
    }

    public Date getUpdatedDate() {
        return updatedDate;
    }

    public void setUpdatedDate(Date updatedDate) {
        this.updatedDate = updatedDate;
    }

    public int getCollectionId() {
        return collectionId;
    }

    public void setCollectionId(int collectionId) {
        this.collectionId = collectionId;
    }

    public String getCollectionName() {
        return collectionName;
    }

    public void setCollectionName(String collectionName) {
        this.collectionName = collectionName;
    }

    public CollectionTypeEntity getCollectionType() {
        return collectionType;
    }

    public void setCollectionTypeId(CollectionTypeEntity collectionType) {
        this.collectionType = collectionType;
    }

    public boolean isActive() {
        return active;
    }

    public void setActive(boolean active) {
        this.active = active;
    }
}

持久性.xml：

<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
    http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
    <persistence-unit name="maria_pu">
        <provider>com.impetus.kundera.KunderaPersistence</provider>
        <class>com.example.spring.hibernate.CollectionEntity</class>
        <class>com.example.spring.hibernate.CollectionTypeEntity</class>

        <properties>
            <property name="kundera.client.lookup.class" value="com.impetus.client.rdbms.RDBMSClientFactory" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
            <property name="hibernate.connection.driver_class" value="org.mariadb.jdbc.Driver" />
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/mydb" />
            <property name="hibernate.connection.username" value="root" />
            <property name="hibernate.connection.password" value="" />
            <property name="hibernate.current_session_context_class" value="thread"/>
        </properties>
    </persistence-unit>
</persistence>

网页.xml：

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app id="WebApp_ID" version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

  <display-name>Spring Hello World Application</display-name>

    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

最后是 dispatcher.servlet.xml：

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/tx
            http://www.springframework.org/schema/tx/spring-tx.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
            http://www.springframework.org/schema/data/jpa
            http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="com.example.spring" />

    <jpa:repositories base-package="com.example.spring.repositories"/>

    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="maria_pu"/>
    </bean>

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

    <tx:annotation-driven transaction-manager="transactionManager"/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix">
            <value>/WEB-INF/views/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>

    </bean>
</beans>

正如我所说，我是 Spring 新手，所以我可能只是缺少一些配置参数。任何帮助是极大的赞赏！