我需要在GSON中使用自己的ExclusionStrategy，所以我创建了此类：
public class DUExclusionStrategy implements ExclusionStrategy {
public boolean shouldSkipField(FieldAttributes f) {
Collection<Annotation> annots = f.getAnnotations();
for(Annotation a : annots) {
if(a.annotationType().equals(Expose.class)) {
return false;
}
}
return (f.getDeclaringClass() == BaseEntityImpl.class && f.getName().equals("creation"))
|| (f.getDeclaringClass() == BaseEntityImpl.class && f.getName().equals("creator"))
|| (f.getDeclaringClass() == BaseEntityImpl.class && f.getName().equals("modification"))
|| (f.getDeclaringClass() == BaseEntityImpl.class && f.getName().equals("modificator"));
}
public boolean shouldSkipClass(Class<?> clazz) {
return false;
}
}
我不应该在BaseEntityImpl中进行任何更改，并且此类中包含以下字段：
@OneToMany(mappedBy="parent", fetch=FetchType.LAZY) @OrderBy("ordinal")
private Set<T> children = new TreeSet<T>();
而且由于调用
f.getDeclaringClass()，应用程序引发了此异常：org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: cz.bach.dataframe2.domain.impl.BaseEntityImpl.children, could not initialize proxy - no Session
at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:566)
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:186)
at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:545)
at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:124)
at org.hibernate.collection.internal.PersistentSet.iterator(PersistentSet.java:180)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:95)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:60)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89)
at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195)
at com.google.gson.Gson.toJson(Gson.java:593)
at com.google.gson.Gson.toJson(Gson.java:572)
at com.google.gson.Gson.toJson(Gson.java:527)
at com.google.gson.Gson.toJson(Gson.java:507)
at cz.bach.clients.du.model.service.DUSerializer.serialize(DUSerializer.java:23)
at cz.bach.clients.du.model.service.DURepository.save(DURepository.java:619)
at cz.bach.clients.du.model.service.DURepository.appendChild(DURepository.java:176)
at cz.bach.clients.du.model.service.DURepository.appendChild(DURepository.java:150)
at cz.bach.clients.du.model.service.DURepository$$FastClassByCGLIB$$f2fe0d5d.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:191)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:689)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:90)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622)
at cz.bach.clients.du.model.service.DURepository$$EnhancerByCGLIB$$a27cbe9c.appendChild(<generated>)
at cz.bach.clients.du.ui.perspectives.main.DUDispatcher.add(DUDispatcher.java:261)
at cz.bach.archives.uiframe.actions.CommonAddAction.run(CommonAddAction.java:11)
at cz.bach.clients.du.ui.perspectives.main.DUToolbar$1.buttonClick(DUToolbar.java:71)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)
at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219)
at com.vaadin.ui.Button.fireClick(Button.java:567)
at com.vaadin.ui.Button.changeVariables(Button.java:223)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1460)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1404)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1329)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:761)
at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:325)
at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:83)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
我可以通过简单优雅的方式解决此问题吗？我真的不知道为什么
getDeclaringClass()应该引起BaseEntityImpl的完全初始化的任何原因。提前致谢！
最佳答案
在BaseEntityImpl实体中，将fetchType懒惰更改为Eager，即
@OneToMany(mappedBy="parent", fetch=FetchType.EAGER)