在jsp用户怎么读取指定目录下的文件列表（急！！！要吐血了）

各位大虾，帮帮我，写了一个读取指定目录下的文件的类，在jsp文件中调用，老是出错，请问怎么解决！下面是代码：
package  yuletiandi
import java.io.File;
import java.util.Date;
import java.util.Iterator;
import java.util.Vector;public class FileViewer{
        File myDir;
        File[] contents;
        Vector vectorList;
        Iterator currentFileView;
        File currentFile;
        String path;
        
        public FileViewer(){
                path=new String("");                        
                vectorList=new Vector();
        }
        public FileViewer(String path){
                this.path=path;
                vectorList=new Vector();
        }        
        /**
         * 设置浏览的路径
        */
        public void setPath(String path){
                this.path=path;
        }
        
        /***
         * 返回当前目录路径
        */
        public String getDirectory(){
                return myDir.getPath();
        }
        
        /**
         * 刷新列表
        */
        public void refreshList(){
                if(this.path.equals("")) path="c:\\";
                myDir=new File(path);
                
                vectorList.clear();
                contents =myDir.listFiles();
                //重新装入路径下文件
                for(int i=0;i<contents.length;i++){
                        vectorList.add(contents[i]);
                }
                currentFileView=vectorList.iterator();
        }
        /**
         * 移动当前文件集合的指针指到下一个条目
         * @return 成功返回true,否则false
        */
        public boolean nextFile(){
                while(currentFileView.hasNext()){
                        currentFile=(File)currentFileView.next();
                        return true;
                }
                return false;
        }
        
        /**
         * 返回当前指向的文件对象的文件名称
        */
        public String getFileName(){
                return currentFile.getName();
        }
        
        
        /**
         * 返回当前指向的文件对象的文件尺寸
        */
        public String getFileSize(){
                return new Long(currentFile.length()).toString();
        }        /**
         * 返回当前指向的文件对象的最后修改日期
        */        
        public String getFileTimeStamp(){
                return new Date(currentFile.lastModified()).toString();
        }
        
        /**
         * 返回当前指向的文件对象是否是一个文件目录
        */
        public boolean getFileType(){
                return currentFile.isDirectory();
        }
}
下面是页面代码：
<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %><html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head><body>
<p>电影列表</p>
<%@ page  import=" java.io.File,java.util.Date,java.util.Iterator,java.util.Vector" %>
<jsp:useBean id="file" class="yuletiandi.FileViewer" scope="page" />
<%  
file.setPath("C:\\Tomcat 5.0\\webapps\\myapp\\yuletiandi\\dianyingwenjianjia");   
                file.refreshList();
                while(file.nextFile()){
                        System.out.print(file.getFileName());
                        if(!file.getFileType())
                                System.out.print("  "+file.getFileSize());
                        else
                                System.out.print("  <DIR>");
                        System.out.print(file.getFileTimeStamp()+"\n");
                }
%>
<p>&nbsp;</p>
<p>&nbsp; </p>
</body>
</html>运行后的结果：type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: /yuletiandi/listdianying.jsp(12,0) The value for the useBean class attribute yuletiandi.FileViewer is invalid.
org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:39)
org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409)
org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:150)
org.apache.jasper.compiler.Generator$GenerateVisitor.visit(Generator.java:1227)
org.apache.jasper.compiler.Node$UseBean.accept(Node.java:1116)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Node$Visitor.visitBody(Node.java:2213)
org.apache.jasper.compiler.Node$Visitor.visit(Node.java:2219)
org.apache.jasper.compiler.Node$Root.accept(Node.java:456)
org.apache.jasper.compiler.Node$Nodes.visit(Node.java:2163)
org.apache.jasper.compiler.Generator.generate(Generator.java:3272)
org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:244)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:495)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:476)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:464)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.0.30 logs.
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求各位帮我看看！