【问题标题】：Why .jsp page is not displaying on a browser?为什么 .jsp 页面没有显示在浏览器上？
【发布时间】：2014-05-07 15:31:17
【问题描述】：

我在 Eclipse 中创建了一个简单的 Web 应用程序项目。它包括 -

一个jsp页面
一个 servlet 和
一个 html 文件。

jsp 页面只包含一个要打印的文本

你好

在谷歌应用引擎上部署这个项目后，唯一的html页面就是get display。对于 jsp 页面，它显示 500 服务器错误。为什么会这样？ web.xml

`<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
    <servlet>
        <servlet-name>Checkgoogleapp</servlet-name>
        <servlet-class>com.app.checkgoogleapp.CheckgoogleappServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Checkgoogleapp</servlet-name>
        <url-pattern>/checkgoogleapp</url-pattern>
    </servlet-mapping>
    <context-param>
 <param-name>com.sun.faces.enableThreading</param-name>
 <param-value>false</param-value>
 </context-param> 
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
</web-app>`

这是错误日志

W 2014-03-28 01:45:54.477

EXCEPTION 
java.lang.IllegalArgumentException
    at com.google.appengine.runtime.Request.process-16aacb2b4ef7a208(Request.java)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:360)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:188)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at java.lang.Thread.run(Thread.java:724)

E 2014-03-28 01:45:54.478

javax.servlet.ServletContext log: unavailable
javax.servlet.UnavailableException
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:79)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:188)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:724)

W 2014-03-28 01:45:54.479

Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@9c019f{/,/base/data/home/apps/s~app-anuja/1.374734901225985743}
java.lang.NullPointerException
    at java.lang.Class.isAssignableFrom(Native Method)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:219)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:188)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:724)

C 2014-03-28 01:45:54.481

Uncaught exception from servlet
javax.servlet.UnavailableException: Initialization failed.
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:228)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:194)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:134)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:437)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:444)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:188)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:308)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:300)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:441)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
    at java.lang.Thread.run(Thread.java:724)

【问题讨论】：

GAE 日志说什么？
Well 500 是服务器错误，因此您应该检查服务器的日志以了解实际错误是什么。
您好 Joachim EXCEPTION java.lang.IllegalArgumentException at com.google.appengine.runtime.Request.process- javax.servlet.ServletContext 日志：org.mortbay.jetty.servlet 不可用 javax.servlet.UnavailableException .Holder.doStart(Holder.java:79) 在 org。 W com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@9c019f{/,/base/data/home/apps/s~app-anuja/1.3747349012259857 C 2014-03-28 01:45:54.481 未捕获来自 servlet javax 的异常。 servlet.UnavailableException：初始化失败。在 com.google.apphosting.runtime.jetty.AppVersionHandlerMa
嗨，Thomas，上面提到的这些异常显示在服务器日志中。
请帮帮我。我正在尝试从过去 1 个月开始解决这个问题。

标签： java html eclipse jsp

【解决方案1】：

在 web.xml 中添加以下代码并尝试

 <context-param>
 <param-name>com.sun.faces.enableThreading</param-name>
 <param-value>false</param-value>
 </context-param>

【讨论】：

感谢您的建议，但仍然存在同样的问题。
-1 没有解释为什么他应该这样做以及“代码”的作用。只需“尝试”
Checkgoogleappcom.app.checkgoogleapp.CheckgoogleappServletCheckgoogleapp/checkgoogleappcom.sun.faces.enableThreading param-name> falseindex.html
这个问题有解决办法吗？
在我的应用程序中，如果我曾经添加简单的 servlet，那么它工作得很好，但是当我们添加带有 servlet 的 jsp 时，它会在 Web 浏览器中显示 500。