如何序列化AutoBean（GWT）中的列表？

我想弄清楚如何在GWT中使用AutoBean序列化一個列表，但我不斷得到一個空指針異常。如何序列化AutoBean（GWT）中的列表？

這是我有：

GuideCreatorFactory beanFactory = AutoBeanFactorySource.create(GuideCreatorFactory.class); 

    List<Guide> guides = new LinkedList<Guide>(); 
    Guide guide = new Guide(); 
    guide.setText("this is the text"); 
    guide.setTitle("this is the title"); 
    guides.add(guide); 

    GuideCreatorList<Guide> impl = new GuideCreatorListImpl(); 
    impl.setGuides(guides); 

    System.out.println("Serializing the given parameter to JSON"); 

    // Fails on the below lines w/ NPE 
    AutoBean<GuideCreatorList> bean = beanFactory.create(GuideCreatorList.class, impl); 
    String json = AutoBeanCodex.encode(bean).getPayload(); 
    System.out.println("guides as json: " + json);

誰能幫我指出了正確的方向？非常感謝你。

下面是支持類和接口：

public interface GuideCreatorFactory extends AutoBeanFactory { 
    AutoBean<GuideCreator> createGuide(); 

    AutoBean<GuideCreatorList> createGuideList(); 
} 


public interface GuideCreator { 

    public String getText(); 

    public void setText(String text); 

    public String getTitle(); 

    public void setTitle(String title); 

} 


public interface GuideCreatorList<T extends GuideCreator> { 
    public List<T> getGuides(); 

    public void setGuides(List<T> guides); 
} 



class GuideCreatorListImpl implements GuideCreatorList<Guide> { 
    private List<Guide> guides; 

    public GuideCreatorListImpl() { 

    } 

    @Override 
    public List<Guide> getGuides() { 
     return guides; 
    } 

    @Override 
    public void setGuides(List<Guide> guides) { 
     this.guides = guides; 
    } 
    };

這裏的NPE：

java.lang.NullPointerException 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl.doEncode(AutoBeanCodexImpl.java:558) 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$ObjectCoder.encode(AutoBeanCodexImpl.java:321) 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$CollectionCoder.encode(AutoBeanCodexImpl.java:163) 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$PropertyGetter.encodeProperty(AutoBeanCodexImpl.java:413) 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$PropertyGetter.visitReferenceProperty(AutoBeanCodexImpl.java:389) 
    at com.google.web.bindery.autobean.shared.AutoBeanVisitor.visitCollectionProperty(AutoBeanVisitor.java:229) 
    at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:300) 
    at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166) 
    at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101) 
    at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl.doEncode(AutoBeanCodexImpl.java:558) 
    at com.google.web.bindery.autobean.shared.AutoBeanCodex.encode(AutoBeanCodex.java:83) 
    at com.districthp.core.ui.client.review.JsonSerializationText.testMyObject(JsonSerializationText.java:82) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
    at java.lang.reflect.Method.invoke(Method.java:597) 
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) 
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) 
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) 
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20) 
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28) 
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49) 
    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.junit.runners.ParentRunner.run(ParentRunner.java:236) 
    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)

來源

2012-07-17 Cuga

你可以給NPE的完整堆棧跟蹤嗎？ – 2012-07-17 21:43:35

我添加了堆棧跟蹤...謝謝。 – Cuga 2012-07-17 22:03:30

這是不幸的是一個已知的問題：https://github.com/gwtproject/gwt/issues/6903

的問題是，該列表中的項目沒有包入AutoBean s所以AutoBeanUtils#getAutoBean在AutoBeanCodexImpl.ObjectCoder#encode返回null，母雞在AutoBeanCodexImpl#doEncode的NPE。

解決方法是用包含實際值的AutoBean來替換列表項。

來源

2012-07-17 23:29:17

你絕對是對的。非常感謝 – Cuga 2012-07-18 15:42:40

如何序列化AutoBean（GWT）中的列表？

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