How to do a file upload & download using Apache Commons FileUpload?

Question

Hi, I have read through the user guide but I don't understand what are the steps as to implementing the functions...
http://commons.apache.org/fileupload/using.html
How do I Create a servlet to read the contents(filename) of te dir where the files are, then create a collection (ArrayList for instance) with the files path and send this collection back to a jsp page.In jsp page, iterate through the collection and build the links (with scriptlets or c tags)
Can help? Thanks for the guidance!

Answer 1

This is my single_upload_page.jsp
<%@ page import="java.io.*" %>
<%
     //to get the content type information from JSP Request Header
     String contentType = request.getContentType();
     //here we are checking the content type is not equal to Null and
//as well as the passed data from mulitpart/form-data is greater than or
//equal to 0
     if ((contentType != null) && (contentType.indexOf("multipart/form-data") >= 0)) {
          DataInputStream in = new DataInputStream(request.getInputStream());
          //we are taking the length of Content type data
          int formDataLength = request.getContentLength();
          byte dataBytes[] = new byte[formDataLength];
          int byteRead = 0;
          int totalBytesRead = 0;
          //this loop converting the uploaded file into byte code
          while (totalBytesRead < formDataLength) {
               byteRead = in.read(dataBytes, totalBytesRead, formDataLength);
               totalBytesRead += byteRead;
          String file = new String(dataBytes);
          //for saving the file name
          String saveFile = file.substring(file.indexOf("filename=\"") + 10);
          saveFile = saveFile.substring(0, saveFile.indexOf("\n"));
          saveFile = saveFile.substring(saveFile.lastIndexOf("\\")+ 1,saveFile.indexOf("\""));
          int lastIndex = contentType.lastIndexOf("=");
          String boundary = contentType.substring(lastIndex + 1,contentType.length());
          int pos;
          //extracting the index of file
          pos = file.indexOf("filename=\"");
          pos = file.indexOf("\n", pos) + 1;
          pos = file.indexOf("\n", pos) + 1;
          pos = file.indexOf("\n", pos) + 1;
          int boundaryLocation = file.indexOf(boundary, pos) - 4;
          int startPos = ((file.substring(0, pos)).getBytes()).length;
          int endPos = ((file.substring(0, boundaryLocation)).getBytes()).length;
          // creating a new file with the same name and writing the content in new file
          String folder = "C:/Program Files/Apache Software Foundation/Tomcat 5.5/webapps/ROOT/test/x/";     
          FileOutputStream fileOut = new FileOutputStream(folder + saveFile);     
                         //out.print("Saved here: " + saveFile);     
                         //fileOut.write(dataBytes);     
          fileOut.write(dataBytes, startPos, (endPos - startPos));
          fileOut.flush();
          fileOut.close();
          %><Br><table border="2"><tr><td><b>You have successfully upload the file by the name of:</b>
          <% out.println(saveFile); %></td></tr></table> <%
%>