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java - JSF 隐藏异常？

转载 作者：塔克拉玛干 更新时间：2023-11-02 20:19:18 27 4
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我有一个 JSF 页面的托管 bean，它在构造函数中执行 JPA 调用以填充 bean 中的字段。我在调用另一个持久化实体(填充数据以进行测试)时遇到了一些麻烦。我期望它会抛出某种异常，因为它不起作用，但我什么也没得到。真见鬼，我尝试了以下操作:

Query newQuery = em.createQuery("Bad Syntax");
List newList = newQuery.getResultList();

由于查询字符串完全无效，我希望此处出现 IllegalArgumentException，但页面仍在加载，而且我在任何地方都没有看到任何异常。

我对这个异常的预期是否正确？如果是这样，为什么我没有看到它？

最佳答案

默认情况下它不会抑制异常。作为快速测试，我尝试了以下操作:

package com.example;

import javax.faces.bean.ManagedBean;

@ManagedBean
public class Bean {

    public Bean() {
        throw new IllegalArgumentException("No!");
    }

}

与

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" 
      xmlns:h="http://java.sun.com/jsf/html">
    <h:head>
        <title>test</title>
    </h:head>
    <h:body>
        #{bean}
    </h:body>
</html>

我在网络浏览器中得到了一个不错的默认错误页面，其中包含以下跟踪:

javax.el.ELException: /test.xhtml: Cant instantiate class: com.example.Bean.
    at com.sun.faces.facelets.compiler.TextInstruction.write(TextInstruction.java:83)
    at com.sun.faces.facelets.compiler.UIInstructions.encodeBegin(UIInstructions.java:75)
    at com.sun.faces.facelets.compiler.UILeaf.encodeAll(UILeaf.java:176)
    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 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:128)
    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:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
    at java.lang.Thread.run(Thread.java:619)
Caused by: com.sun.faces.mgbean.ManagedBeanCreationException: Cant instantiate class: com.example.Bean.
    at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:193)
    at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:102)
    at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:405)
    at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:267)
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:86)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:61)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    at com.sun.faces.facelets.el.ELText$ELTextVariable.writeText(ELText.java:217)
    at com.sun.faces.facelets.el.ELText$ELTextComposite.writeText(ELText.java:141)
    at com.sun.faces.facelets.compiler.TextInstruction.write(TextInstruction.java:78)
    ... 25 more
Caused by: java.lang.IllegalArgumentException: No!
    at com.example.Bean.<init>(Bean.java:9)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at java.lang.Class.newInstance0(Class.java:355)
    at java.lang.Class.newInstance(Class.java:308)
    at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:188)
    ... 36 more
1-jun-2010 13:51:06 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet Faces Servlet threw exception
java.lang.IllegalArgumentException: No!
    at com.example.Bean.<init>(Bean.java:9)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at java.lang.Class.newInstance0(Class.java:355)
    at java.lang.Class.newInstance(Class.java:308)
    at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:188)
    at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:102)
    at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:405)
    at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:267)
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:86)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:54)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:61)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    at com.sun.faces.facelets.el.ELText$ELTextVariable.writeText(ELText.java:217)
    at com.sun.faces.facelets.el.ELText$ELTextComposite.writeText(ELText.java:141)
    at com.sun.faces.facelets.compiler.TextInstruction.write(TextInstruction.java:78)
    at com.sun.faces.facelets.compiler.UIInstructions.encodeBegin(UIInstructions.java:75)
    at com.sun.faces.facelets.compiler.UILeaf.encodeAll(UILeaf.java:176)
    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 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:128)
    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:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
    at java.lang.Thread.run(Thread.java:619)

所以您的问题可能出在其他地方。你运行调试器了吗？

关于java - JSF 隐藏异常？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/2946484/

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