Struts2当调用action时出现HTTP Status 404 问题解决

之前碰到这一个问题，在网上查找解决方法，改了两天也没有解决，今天重新建了一个工程一开始还是出错了，后来查看Console的信息发现以下问题：

严重: Exception starting filter struts2
java.lang.NoClassDefFoundError: org/apache/commons/lang3/StringUtils
	at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.register(XmlConfigurationProvider.java:213)
	at org.apache.struts2.config.StrutsXmlConfigurationProvider.register(StrutsXmlConfigurationProvider.java:102)
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:240)
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67)
	at org.apache.struts2.dispatcher.Dispatcher.getContainer(Dispatcher.java:970)
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:438)
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:482)
	at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:57)
	at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
	at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4908)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5602)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1572)
	at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1562)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.lang3.StringUtils
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1858)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1701)
	... 21 more

发现缺少了一个包，就是commons-lang3-3.2.jar这个包，添加进去后问题就解决了，下面一步一步建立可以执行的这个工程

首先，我的工程结构如下：

注意，复制到WebContent下的WEB-INF下的lib中的jar包总共有以下12个！

第一步，创建工程的时候勾选自动创建web.xml文件，如下图点击next

进入如下界面，再点击next

进入下一个界面，勾选Generate web.xml deployment descriptor,再点击finish就可以创建出web.xml文件了

编写web.xml的配置信息，注意Struts2使用的过滤器类是org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter，以下为我的web.xml的代码：

<?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"
		 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>StrutsDemo02</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <filter>
        <!-- 定义核心Filter的名字 -->
        <filter-name>struts2</filter-name>
        <!-- 定义核心Filter的实现类 -->
        <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

然后，在src文件右击选择New->Other,在弹出的文本框中的General选项下选择“file”，点击next，将文件名命名为struts.properties，完成后在struts.properties文件中写入

<struts.i18n.encoding value="UTF-8"/>

接下来在src文件夹下创建struts.xml,我的代码如下，文件中声明了一个名字为hello的action，该action对应的类为com.action.TestAction，返回结果为success.jsp页面

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
   "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
   "http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
   <package name="default" namespace="/" extends="struts-default">
      <action name="hello" class="com.action.TestAction" >
            <result>/success.jsp</result>
      </action>
   </package>
</struts>

然后在src下创建包com.action，在包下创建TestAction.java,我的代码如下

import com.opensymphony.xwork2.ActionSupport;

public class TestAction extends ActionSupport {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	
	private String helo;
	//helo的getter与setter
	public String getHelo() {
		return helo;
	}
	public void setHelo(String hello) {
		this.helo = hello;
	}
	
	@Override
	public String execute() throws Exception {
		// TODO Auto-generated method stub
		helo="hello struts";
		return SUCCESS;
	}
}

最后，在WebContent下创建index.jsp文件与success.jsp文件，写jsp页面时要注意在头部加上<%@ taglib prefix="s" uri="/struts-tags"%>，引入struts的标签库

index.jsp文件内容

<%@ 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>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<!-- Struts的超链接标签，链接一个名为hello的action -->
<s:a action="hello">hello</s:a>
</body>
</html>

success.jsp页面内容

<%@ 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>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<s:property value="helo"/>
</body>
</html>

到此，右键工程，Run on Sever就成功了！

点击hello