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struts2-求高手指點，第一次運行Struts2就有這樣的錯，看了很久了....

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求高手指點，第一次運行Struts2就有這樣的錯，看了很久了....

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代碼如下

 package example;

/**
 *
 * @author kekeson
 */
public class HelloWorldStruts {

    private String name;

    public String execute() throws Exception {
        return "success";
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
    <include file="example.xml"/>
    <!-- Configuration for the default package. -->
    <constant name="struts.devMode" value="true" />
    <package name="example" namespace="/example" extends="struts-default">
        <action name="hello"
                class="example.HelloWorldStruts"
                method="execute">
            <result name="success">/example/HelloWorld2.jsp</result>
        </action>
    </package>
</struts>

 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
         pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
        <title>Hello World</title>
    </head>
    <body>
        <h1>Hello World From Struts2</h1>
        <form action="hello">
            <label for="name">Please enter your name</label><br/>
            <input type="text" name="name"/>
            <input type="submit" value="Say Hello"/>
        </form>
    </body>
</html>

 <%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Hello World!, <s:property value="name"/></h1>
    </body>
</html>

 <?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <filter>
        <filter-name>struts2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>example/index.jsp</welcome-file>
    </welcome-file-list>

</web-app>

錯誤如下：

 Struts Problem Report

Struts has detected an unhandled exception:
Messages:   
File:   org/apache/struts2/impl/StrutsActionProxy.java
Line number:    69
Stacktraces
java.lang.NullPointerException

    org.apache.struts2.impl.StrutsActionProxy.getErrorMessage(StrutsActionProxy.java:69)
    com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:185)
    org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:63)
    org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
    com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:58)
    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:553)
    org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:434)
    org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
    org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
    org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:442)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1082)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:623)
    org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2517)
    org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2506)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    java.lang.Thread.run(Thread.java:745)


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