带有 GAE 和 ViewScoped ManagedBean 的 JSF2 [英] JSF2 with GAE and ViewScoped ManagedBean

问题描述

我设法在 Google AppEngine 中使用 JSF2 获得了一个原型，遵循此教程.现在我对 ViewScoped ManagedBean 有一些奇怪的行为:

I managed to get a prototype with JSF2 get working at Googles AppEngine following this tutorial. Now I have some odd behavior with a ViewScoped ManagedBean:

@ManagedBean @ViewScoped
public class TestBean implements Serializable
{
  private String text;         //getter/setter
  private List<String> texts;    //getter

  @PostConstruct public void init() 
  {
    texts = new ArrayList<String>();
    texts.add("Test");
    text = new String();
  }

  public void save(ActionEvent ae)
  {  
    texts.add(text);
    text = new String();
  }
}

这是我的 .xhtml 页面:

This is my .xhtml page:

<h:body id="body">
  <f:view contentType="text/html">
     <h:form id="frm">
        <p:panel>  
            <h:panelGrid columns="2" id="grid">   
                <p:inputText value="#{testBean.text}"/>  
                <p:commandButton value="Add" update=":frm:op @parent"
                                actionListener="#{testBean.save}" />   
            </h:panelGrid>
        </p:panel>
        <p:outputPanel id="op">
           <p:dataTable var="v" value="#{testBean.texts}">  
              <p:column><h:outputText value="#{v}" /></p:column>
           </p:dataTable>
        </p:outputPanel>
     </h:form>
  </f:view>
</h:body>

这适用于本地部署(使用适用于 GAE 的 Eclipse 工具)，但如果我将其部署到 GAE，则单击添加按钮不会发生任何事情.单击添加后，具有范围的其他测试(在 GAE)显示以下内容:

This works fine with a local deployment (Using the Eclipse tools for GAE), but if I deploy this to GAE, nothing happens if I click on the Add-Button. Additional Tests with the scope (at GAE) show the following after clicking on Add:

• @RequestScoped:输入的文本没有消失，没有添加到dataTable
• @ViewScoped:输入的文本没有消失，没有添加到dataTable
• @SessionScoped:输入的文本消失，dataTable总是有两个条目:测试"和最后输入的文本

• @RequestScoped: Entered Text does not disappear, not added to dataTable
• @ViewScoped: Entered Text does not disappear, not added to dataTable
• @SessionScoped: Entered Text disappear, dataTable always has two entries: "Test" and the last entered Text

我有与教程相同的设置

<context-param>  //web.xml
  <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
  <param-value>server</param-value>
</context-param>

//appengine-web.xml
<sessions-enabled>true</sessions-enabled>

更新 1

以下是带有 @ManagedBean @ViewScoped 注释的附加测试的结果:

Here are the results of additional tests with @ManagedBean @ViewScoped annotation:

在第一次请求(或手动刷新页面)期间，@PostConstruct init() 方法被调用.如果我点击按钮 nothing happes，对 test.jsf 的请求会记录在应用引擎日志中，但我的 save()<中没有日志/代码>方法.Firebug 向我展示了对 test.jsf 的 POST 请求和以下答案:

During the first request (or manual refreh of the page), the @PostConstruct init() method is called. If I click on the button nothing happes, the request to test.jsf is logged in app engines log, but there is no log in my save() method. Firebug shows me a POST request to test.jsf and the following answer:

<?xml version='1.0' encoding='UTF-8'?>
<partial-response><error>
  <error-name>class javax.faces.application.ViewExpiredException</error-name>
  <error-message>
     <![CDATA[viewId:/test.jsf - View /test.jsf could not be restored.]]>
  </error-message>
  </error>
  <extension primefacesCallbackParam="validationFailed">
    {"validationFailed":false}
  </extension>
</partial-response>

更新 2

我使用过 mojarra-2.0.4 但现在更新到 2.0.6.同样的问题，但有一个新的观察:如果我清除所有 Firefox 缓存，ViewExpiredException 不会出现，但我只能向 List.@PostConstruct 只调用一次，而不是每次点击按钮时调用.

I have used mojarra-2.0.4 but now updated to 2.0.6. The same issue, but a new observation: If I clear all Firefox caches, the ViewExpiredException did not appear, but I'm only able to add 1 Element to the List<String>. The @PostConstruct is only invoked once and not for each click on the button.

然后我尝试了 myfaces-2.0.7，但得到了这个异常:

Then I tried myfaces-2.0.7, but got this exception:

Uncaught exception from servlet
java.lang.NoClassDefFoundError: Could not initialize class
com.google.apphosting.runtime.security.shared.stub.javax.naming.InitialContext

我不确定我是否应该尝试让 myfaces 工作，因为谷歌在他们的教程中明确提到了 mojarra (2.0.4).

I'm not sure if I should try to get myfaces working since google explicitly mentions mojarra (2.0.4) in their tutorial.

参考资料

• GAE 上的ViewExpiredException
• JIRA JAVASERVERFACES-1886

推荐答案

通常我不回答我的问题，我只将此答案评为解决方法，而不是正确答案.如果我不喜欢保存客户端状态，这似乎解决了奇怪的行为.但我必须详细检查一下:

Normally I don't answer my questions and I only rate this answer as a workaround and not as the correct answer. Event if I don't like client state saving, this seems to fix the odd behavior. But I have to check this in detail:

<context-param>
  <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
  <param-value>client</param-value>
</context-param>

也许我们应该等到 JAVASERVERFACES-1886 解决.

Perhaps we should wait until JAVASERVERFACES-1886 is resolved.

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