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如果我们没有相关页面所需的信息，我无法从视图范围的bean重定向。 @PostContruct中的日志条目在与试图呈现它的视图有关的NPE之前的日志中可见，而不是在我的重定向之后。为什么忽略重定向？似乎无法从ViewScoped构造函数重定向
这里是我的代码：
@ManagedBean
public class WelcomeView {
private String sParam;
private String aParam;
public WelcomeView() {
super();
sParam = getURL_Param("surveyName");
aParam = getURL_Param("accountName");
project = fetchProject(sParam, aParam);
}
@PostConstruct
public void redirectWithoutProject() {
if (null == project) {
try {
logger.warn("NO project [" + sParam + "] for account [" + aParam + "]");
FacesContext fc = FacesContext.getCurrentInstance();
fc.getExternalContext().redirect("/errors/noSurvey.jsf");
return;
} catch (Exception e) {
e.printStackTrace();
}
}
}
....
public boolean getAuthenticated() {
if (project.getPasswordProtected()) {
return enteredPassword.equals(project.getLoginPassword());
} else return true;
}
}
这里的堆栈跟踪：
SEVERE: Error Rendering View[/participant/welcome.xhtml]
javax.el.ELException: /templates/participant/welcome.xhtml @80,70 rendered="#{welcomeView.authenticated}": Error reading 'authenticated' on type com.MYCODE.general.controllers.participant.WelcomeView
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:107)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.UIComponentBase.isRendered(UIComponentBase.java:416)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1607)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.MYCODE.general.filters.StatsFilter.doFilter(StatsFilter.java:28)
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.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:568)
at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:421)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:637)
Caused by: java.lang.NullPointerException
at com.MYCODE.general.controllers.participant.WelcomeView$$M$863c205f.getAuthenticated(WelcomeView.java:127)
at com.MYCODE.general.controllers.participant.WelcomeView$$A$863c205f.getAuthenticated(<generated>)
at com.MYCODE.general.controllers.participant.WelcomeView.getAuthenticated(WelcomeView.java:125)
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 javax.el.BeanELResolver.getValue(BeanELResolver.java:62)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:118)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
... 33 more
请注意，我已经尝试将相同的功能直接放入构造函数而不是@PostConstruct。我也尝试过派发和sendRedirect。 – Andrew 2010-07-19 11:08:13
请更新您的问题以包含NPE的堆栈跟踪。 – BalusC 2010-07-19 11:23:57
我已经添加了堆栈跟踪。它指的是getAuthenticated方法，NPE是因为项目为空，所以我也添加了这个。所以我从你想看到从构造函数重定向的堆栈是一个有效的事情来做，而我的代码做到这一点很好，问题在其他地方呢？ – Andrew 2010-07-19 21:41:48