jsp中的tomcat问题
我用eclipse开发了一个tomcat   项目jspstudy,前几个jsp,servlet程序都可以运行正常,但是我又写了一个SessionExample.java程序和一个名为SessionServlet.jsp页面,启动tomcat却显示这样的错误: 
 HTTP   Status   404   -   /jspstudy/   
 --------------------------------------------   
 type   Status   report   
 message   /jspstudy/   
 description   The   requested   resource   (/jspstudy/)   is   not   available. 
 以前的几个程序都可以运行啊!!! 
 SessionServlet.jsp:源代码: 
  <%@   page   language= "java "   contenType= "text/html;charset=gb2312 "%>  
  <html>  
  <center>  
  <title> Session-Servlet测试 </title>  
  <body>  
  <%--设置Session中的共享变量dataName和   dataValue--%>  
  <% 
 	session.putValue( "dataName ", "session-share "); 
 	session.putValue( "dataValue ", "100 "); 
 %>  
  <form   method=post   action= "./SessionExample ">  
 输入数据上限: 
  <input   type=text   name= "dataLimit ">  
  <p>  
  <input   type=submit>  
  </form>  
  </body>  
  </center>  
  </html>  
 Servlet程序SessionExample.java的源代码: 
 /** 
    *   在JSP   和Servlet之间传递数据 
    */ 
 package   test;   
 import   java.io.*; 
 import   java.util.*; 
 import   javax.servlet.*; 
 import   javax.servlet.http.*;   
 /** 
    *   @author   李彬 
    * 
    */ 
 public   class   SessionExample   extends   HttpServlet   {   
 	/** 
 	   *   添加缺省的序列好 
 	   */ 
 	private   static   final   long   serialVersionUID   =   1L; 
 	public   void   doGet(HttpServletRequest   request,HttpServletResponse   response) 
 	throws   
IOException,
ServletException     	{ 
 		response.setContentType( "text/html;charset=gb2312 "); 
 		PrintWriter   out   =   response.getWriter();  		 
 		//从request对象中获得当前用户的Session 
 		HttpSession   session   =   request.getSession(true); 
 		//输出session信息 
 		//获得session创建时间 
 		Date   created   =   new   Date(session.getCreationTime()); 
 		//获得Session最后访问时间 
 		Date   accessed   =   new   Date(session.getLastAccessedTime()); 
 		out.println( "session   ID: "   +   session.getId()   +    " <br>  "); 
 		out.println( "创建时间: "   +   created   +    " <br>  "); 
 		out.println( "上次访问时间: "   +   accessed   +    " <br>  ");  		 
 		//设置Session信息 
 		String   dataName   =   request.getParameter( "dataName "); 
 		if(dataName   !=   null   &&   dataName.length()> 0){ 
 			String   dataValue   =   request.getParameter( "dataValue "); 
 			session.setAttribute(dataName,dataValue); 
 		} 
 		//输出session内容 
 		Enumeration   e   =   session.getAttributeNames(); 
 		while(e.hasMoreElements()){ 
 			String   name   =   (String)e.nextElement(); 
 			String   value   =   session.getAttribute(name).toString(); 
 			out.println(name   +    "= "   + &n