急！急！那位大侠帮我解读下面一段jsp代码！

<html>
<%@ page language="java" import="javazoom.upload.*,java.util.*,java.io.*" %>
<%@ page errorPage="ExceptionHandler.jsp" %><% String directory = "D:/Program Files/Tomcat 5.5/webapps/ROOT/rjgc/upload/uploads/"; %>
<% String tmpdirectory = "D:/Program Files/Tomcat 5.5/webapps/ROOT/rjgc/upload/uploads/tmp"; %>
<% boolean createsubfolders = true; %>
<jsp:useBean id="upBean" scope="page" class="javazoom.upload.UploadBean" >
  <jsp:setProperty name="upBean" property="folderstore" value="<%= directory %>" />
  <jsp:setProperty name="upBean" property="parser" value="<%= MultipartFormDataRequest.CFUPARSER %>"/>
  <jsp:setProperty name="upBean" property="parsertmpdir" value="<%= tmpdirectory %>"/>
  <jsp:setProperty name="upBean" property="filesizelimit" value="8589934592"/>
</jsp:useBean><head>
<title>Samples : Large Upload</title>
<style TYPE="text/css">
<!--
.style1 {
font-size: 12px;
font-family: Verdana;
}
-->
</style>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<ul class="style1">
<%
      if (MultipartFormDataRequest.isMultipartFormData(request))
      {
         // Uses MultipartFormDataRequest to parse the HTTP request.
         MultipartFormDataRequest mrequest = null;
         try
         {
          mrequest = new MultipartFormDataRequest(request,null,-1);
         } catch (Exception e)
       {
        // Cancel current upload (e.g. Stop transfert)
       }         
         String todo = null;
         if (mrequest != null) todo = mrequest.getParameter("todo");
     if ( (todo != null) && (todo.equalsIgnoreCase("upload")) )
     {
                Hashtable files = mrequest.getFiles();
                if ( (files != null) && (!files.isEmpty()) )
                {
                    UploadFile file = (UploadFile) files.get("uploadfile");
                    if (file != null) out.println("<li>Form field : uploadfile"+"<BR> Uploaded file : "+file.getFileName()+" ("+file.getFileSize()+" bytes)"+"<BR> Content Type : "+file.getContentType());
                    // Uses the bean now to store specified by jsp:setProperty at the top.
                    String relative = mrequest.getParameter("relativefilename");
                    if ((createsubfolders == true) && (relative != null))
                    {
            int inda=relative.length();
            int indb=file.getFileName().length();
            if (inda > indb)
            {
               String subfolder = relative.substring(0,(inda-indb)-1);
               subfolder = subfolder.replace('\\','/').replace('/',java.io.File.separatorChar);
               upBean.setFolderstore(directory+java.io.File.separator+subfolder);
            }
                    }
                    upBean.store(mrequest, "uploadfile");
                    String chunkidStr = mrequest.getParameter("chunkid");
                    String chunkamountStr = mrequest.getParameter("chunkamount");
                    String chunkbaseStr = mrequest.getParameter("chunkbase");
                    if ((chunkidStr != null) && (chunkamountStr != null) && (chunkbaseStr != null))
                    {
                     int chunkid = Integer.parseInt(chunkidStr);
                     int chunkamount = Integer.parseInt(chunkamountStr);
                     if (chunkid == chunkamount)
                     {
              // recompose file.
              String fname = upBean.getFolderstore()+java.io.File.separator+chunkbaseStr;
              File fread = new File(fname);
              if (fread.canRead()) fname = fname+"."+System.currentTimeMillis();
              FileOutputStream fout = new FileOutputStream(fname);
              byte[] buffer = new byte[4096];
              for (int c=1;c<=chunkamount;c++)
              {
              File filein = new File(upBean.getFolderstore()+java.io.File.separator+chunkbaseStr+"."+c);
              FileInputStream fin = new FileInputStream(filein);
              int read = -1;
              while ((read = fin.read(buffer)) > 0) fout.write(buffer,0,read);
              fin.close();
              filein.delete();
              }
              fout.close();
                     }
                    }
                    upBean.setFolderstore(directory);                    
                }
                else
                {
                  out.println("<li>No uploaded files");
                }
     }
         else out.println("<BR> todo="+todo);
      }
%>
</ul>
<form method="post" action="LargeUpload.jsp" name="upform" enctype="multipart/form-data">
  <table width="60%" border="0" cellspacing="1" cellpadding="1" align="center" class="style1">
    <tr>
      <td align="left"><b>Select a file to upload :</b></td>
    </tr>
    <tr>
      <td align="left"><input type="file" name="uploadfile" size="50"></td>
    </tr>
    <tr>
      <td align="left">
<input type="hidden" name="todo" value="upload">
        <input type="submit" name="Submit" value="Upload">        
        <input type="reset" name="Reset" value="Cancel">
      </td>
    </tr>
  </table>
  <br>
  <br>
  <table border="0" cellspacing="1" cellpadding="0" align="center">
    <tr>
      <td bgcolor="#666666">
        <table width="100%" border="0" cellspacing="1" cellpadding="0" align="center" class="style1">
          <tr>
            <td bgcolor="#FFFFFF"><b><font color="#0000FF">&nbsp;
              HTML tags used in this form : </font></b></td>
          </tr>
          <tr>
            <td bgcolor="#FFFFFF">&nbsp;&lt;<b>form</b>
              <b>method</b>=&quot;<b><font color="#FF0000">post</font></b>&quot;
              <b>action</b>=&quot;<b><font color="#FF0000">LargeUpload.jsp</font></b>&quot;
              name=&quot;upload&quot; <b>enctype</b>=&quot;<b><font color="#FF0000">multipart/form-data</font></b>&quot;&gt;</td>
          </tr>
          <tr>
            <td bgcolor="#FFFFFF">&nbsp;&lt;<b>input</b>
              <b>type</b>=&quot;<b><font color="#FF0000">file</font></b>&quot;
              <b>name</b>=&quot;<font color="#FF0000"><b>uploadfile</b></font>&quot;
              size=&quot;50&quot;&gt;</td>
          </tr>
        </table>
      </td>
    </tr>
  </table>
  <p>&nbsp;</p>
  <p>&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
  <p align="center">&nbsp;</p>
</form>
</body>
</html>

解决方案 »

  1.   

    <html> 
    <%@ page language="java" import="javazoom.upload.*,java.util.*,java.io.*" %> 
    <%@ page errorPage="ExceptionHandler.jsp" %> 
    //脚本中定义几个变量
    <% String directory = "D:/Program Files/Tomcat 5.5/webapps/ROOT/rjgc/upload/uploads/"; %> 
    <% String tmpdirectory = "D:/Program Files/Tomcat 5.5/webapps/ROOT/rjgc/upload/uploads/tmp"; %> 
    <% boolean createsubfolders = true; %> 
    //引入 javaBean 
    <jsp:useBean id="upBean" scope="page" class="javazoom.upload.UploadBean" > 
       <jsp:setProperty name="upBean" property="folderstore" value=" <%= directory %>" /> 
       <jsp:setProperty name="upBean" property="parser" value=" <%= MultipartFormDataRequest.CFUPARSER %>"/> 
       <jsp:setProperty name="upBean" property="parsertmpdir" value=" <%= tmpdirectory %>"/> 
       <jsp:setProperty name="upBean" property="filesizelimit" value="8589934592"/> 
    </jsp:useBean> <head> 
    <title>Samples : Large Upload </title> 
    <style TYPE="text/css"> 
    <!-- 
    .style1 { 
    font-size: 12px; 
    font-family: Verdana; 
    } 
    --> 
    </style> 
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> 
    </head> 
    <body bgcolor="#FFFFFF" text="#000000"> 
    <ul class="style1"> 
    <% 
          //判断是否为 Multipart类型的表单。即 带有文件上传功能的。      if (MultipartFormDataRequest.isMultipartFormData(request)) 
          { 
             // Uses MultipartFormDataRequest to parse the HTTP request. 
             MultipartFormDataRequest mrequest = null; 
             try 
             { 
              mrequest = new MultipartFormDataRequest(request,null,-1); 
             } catch (Exception e) 
           { 
            // Cancel current upload (e.g. Stop transfert) 
           }          
             String todo = null; 
             if (mrequest != null) todo = mrequest.getParameter("todo"); 
         if ( (todo != null) && (todo.equalsIgnoreCase("upload")) ) 
         { 
                    Hashtable files = mrequest.getFiles(); 
                    if ( (files != null) && (!files.isEmpty()) ) 
                    {                     UploadFile file = (UploadFile) files.get("uploadfile"); 
                        if (file != null) out.println(" <li>Form field : uploadfile"+" <BR> Uploaded file : "+file.getFileName()+" ("+file.getFileSize()+" bytes)"+" <BR> Content Type : "+file.getContentType()); 
                        // Uses the bean now to store specified by jsp:setProperty at the top. 
                        String relative = mrequest.getParameter("relativefilename"); 
                        if ((createsubfolders == true) && (relative != null)) 
                        { 
                int inda=relative.length(); 
                int indb=file.getFileName().length(); 
                if (inda > indb) 
                { 
                   String subfolder = relative.substring(0,(inda-indb)-1); 
                   subfolder = subfolder.replace('\\','/').replace('/',java.io.File.separatorChar); 
                   upBean.setFolderstore(directory+java.io.File.separator+subfolder); 
                } 
                        } 
                      //获得各个表单控件的值。                    upBean.store(mrequest, "uploadfile"); 
                        String chunkidStr = mrequest.getParameter("chunkid"); 
                        String chunkamountStr = mrequest.getParameter("chunkamount"); 
                        String chunkbaseStr = mrequest.getParameter("chunkbase"); 
                        if ((chunkidStr != null) && (chunkamountStr != null) && (chunkbaseStr != null)) 
                        { 
                         int chunkid = Integer.parseInt(chunkidStr); 
                         int chunkamount = Integer.parseInt(chunkamountStr); 
                         if (chunkid == chunkamount) 
                         { 
                  // recompose file. 
                  String fname = upBean.getFolderstore()+java.io.File.separator+chunkbaseStr; 
                  File fread = new File(fname); 
                  if (fread.canRead()) fname = fname+"."+System.currentTimeMillis(); 
                  FileOutputStream fout = new FileOutputStream(fname); 
                  //在服务端生成一个新文件。              byte[] buffer = new byte[4096]; 
                  for (int c=1;c <=chunkamount;c++) 
                  { 
                  File filein = new File(upBean.getFolderstore()+java.io.File.separator+chunkbaseStr+"."+c); 
                  FileInputStream fin = new FileInputStream(filein); 
                  int read = -1; 
                  while ((read = fin.read(buffer)) > 0) fout.write(buffer,0,read); 
                  fin.close(); 
                  filein.delete(); 
                  } 
                  fout.close(); 
                         } 
                        } 
                        upBean.setFolderstore(directory);                     
                    } 
                    else 
                    { 
                      out.println(" <li>No uploaded files"); 
                    } 
         } 
             else out.println(" <BR> todo="+todo); 
          } 
    %> 
    </ul> 
    <form method="post" action="LargeUpload.jsp" name="upform" enctype="multipart/form-data"> 
       <table width="60%" border="0" cellspacing="1" cellpadding="1" align="center" class="style1"> 
         <tr> 
           <td align="left"> <b>Select a file to upload : </b> </td> 
         </tr> 
         <tr> 
           <td align="left"> <input type="file" name="uploadfile" size="50"> </td> 
         </tr> 
         <tr> 
           <td align="left"> 
    <input type="hidden" name="todo" value="upload"> 
             <input type="submit" name="Submit" value="Upload">         
             <input type="reset" name="Reset" value="Cancel"> 
           </td> 
         </tr> 
       </table> 
       <br> 
       <br> 
       <table border="0" cellspacing="1" cellpadding="0" align="center"> 
         <tr> 
           <td bgcolor="#666666"> 
             <table width="100%" border="0" cellspacing="1" cellpadding="0" align="center" class="style1"> 
               <tr> 
                 <td bgcolor="#FFFFFF"> <b> <font color="#0000FF">&nbsp; 
                  HTML tags used in this form :  </font> </b> </td> 
               </tr> 
               <tr> 
                 <td bgcolor="#FFFFFF">&nbsp;&lt; <b>form </b> 
                   <b>method </b>=&quot; <b> <font color="#FF0000">post </font> </b>&quot; 
                   <b>action </b>=&quot; <b> <font color="#FF0000">LargeUpload.jsp </font> </b>&quot; 
                  name=&quot;upload&quot;  <b>enctype </b>=&quot; <b> <font color="#FF0000">multipart/form-data </font> </b>&quot;&gt; </td> 
               </tr> 
               <tr> 
                 <td bgcolor="#FFFFFF">&nbsp;&lt; <b>input </b> 
                   <b>type </b>=&quot; <b> <font color="#FF0000">file </font> </b>&quot; 
                   <b>name </b>=&quot; <font color="#FF0000"> <b>uploadfile </b> </font>&quot; 
                  size=&quot;50&quot;&gt; </td> 
               </tr> 
             </table> 
           </td> 
         </tr> 
       </table> 
       <p>&nbsp; </p> 
       <p>&nbsp; </p> 
       <p align="center">&nbsp; </p> 
       <p align="center">&nbsp; </p> 
       <p align="center">&nbsp; </p> 
    </form> 
    </body> 
    </html>