Uploading Image from Java Desktop App to Server

[Sandip Gupta]

I have a desktop application within which i know which image file is to be uploaded....to a server...The desktop application has the following code which sends a request to servlet on the server. The servlet needs to receive the image and save it to a folder on the server.....


//Code on client machine

import java.io.*;
import java.net.*;


public class ServletCom  {

public static void main(String[] args)
      throws Exception
   {

  HttpURLConnection conn = null;
  BufferedReader br = null;
  DataOutputStream dos = null;
  DataInputStream inStream = null;

  InputStream is = null;
  OutputStream os = null;
  boolean ret = false;
  String StrMessage = "";
  String exsistingFileName = "C:\\temp\\screenCapture_20110413_052404.GIF";

  String lineEnd = "\r\n";
  String twoHyphens = "--";
  String boundary =  "*****";


  int bytesRead, bytesAvailable, bufferSize;

  byte[] buffer;

  int maxBufferSize = 1*1024*1024;


  String responseFromServer = "";

  String urlString = "http://localhost:8080/M-Admin_1.0_Web_Module/ReceiveScreenShotServlet";


  try
  {
   //------------------ CLIENT REQUEST

   FileInputStream fileInputStream = new FileInputStream( new
File(exsistingFileName) );

   // open a URL connection to the Servlet 

   URL url = new URL(urlString);


   // Open a HTTP connection to the URL

   conn = (HttpURLConnection) url.openConnection();

   // Allow Inputs
   conn.setDoInput(true);

   // Allow Outputs
   conn.setDoOutput(true);

   // Don't use a cached copy.
   conn.setUseCaches(false);

   // Use a post method.
   conn.setRequestMethod("POST");

   conn.setRequestProperty("Connection", "Keep-Alive");
  
   conn.setRequestProperty("Content-Type", "multipart/form-data;boundary="+boundary);

   dos = new DataOutputStream( conn.getOutputStream() );

   dos.writeBytes(twoHyphens + boundary + lineEnd);
   dos.writeBytes("Content-Disposition: form-data; name=\"upload\";"
      + " filename=\"" + exsistingFileName +"\"" + lineEnd);
   dos.writeBytes(lineEnd);

   

   // create a buffer of maximum size

   bytesAvailable = fileInputStream.available();
   bufferSize = Math.min(bytesAvailable, maxBufferSize);
   buffer = new byte[bufferSize];

   // read file and write it into form...

   bytesRead = fileInputStream.read(buffer, 0, bufferSize);

   while (bytesRead > 0)
   {
    dos.write(buffer, 0, bufferSize);
    bytesAvailable = fileInputStream.available();
    bufferSize = Math.min(bytesAvailable, maxBufferSize);
    bytesRead = fileInputStream.read(buffer, 0, bufferSize);
   }

   // send multipart form data necesssary after file data...

   dos.writeBytes(lineEnd);
   dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

   // close streams

   fileInputStream.close();
   dos.flush();
   dos.close();


  }
  catch (MalformedURLException ex)
  {
   System.out.println("From ServletCom CLIENT REQUEST:"+ex);
  }

  catch (IOException ioe)
  {
   System.out.println("From ServletCom CLIENT REQUEST:"+ioe);
  }


  //------------------ read the SERVER RESPONSE


  try
  {
   inStream = new DataInputStream ( conn.getInputStream() );
   String str;
   while (( str = inStream.readLine()) != null)
   {
    System.out.println("Server response is: "+str);
    System.out.println("");
   }
   inStream.close();

  }
  catch (IOException ioex)
  {
   System.out.println("From (ServerResponse): "+ioex);

  }

  }
   
}

//my servlet code

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package web.servlets;

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.imageio.stream.ImageInputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Sandip
 */
public class ReceiveScreenShotServlet extends HttpServlet {
   
    /** 
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            
            BufferedImage img = null ;
            out.println("1");
            InputStream in = request.getInputStream();
            

            ImageInputStream iis = ImageIO.createImageInputStream(in);
            //File f = new File("http://localhost:8080/M-Admin_1.0_Web_Module/logo.png");
            //URL url = new URL("http://localhost:8080/M-Admin_1.0_Web_Module/logo.png");

            out.println("2");
	    //Image image = ImageIO.read(in);
            out.println("3");
            try{
                img = ImageIO.read(iis);
            }catch(Exception e){out.println(e.getMessage());}
            out.println("4");
            File file = new File("C:\\temp\\image.png");
            out.println("5");
             try{
                ImageIO.write(img, "png", file);
            }catch(Exception e){out.println(e.getLocalizedMessage());}
            out.println("success");
        } finally { 
            out.close();
        }
    } 
   // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /** 
     * Handles the HTTP <code>GET</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    } 

    /** 
     * Handles the HTTP <code>POST</code> method.
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }

    /** 
     * Returns a short description of the servlet.
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>
}
;

However...there is something wrong....I guess i am not processing the request properly...I have tried saving the image file using url and it works fine.....can some one guide me ...on how to receive a request and process it as image and save it to disk.....However if please point out if there is any error with the code on the client desktop application,.....

[Rob Spoor]

I'd use Apache Commons HttpClient and FileUpload libraries to do the dirty work for you.

[Sandip Gupta]

Yes got it correct with HttpClient and FileUpload.....thanks for the suggestion.....

[Rob Spoor]

You're welcome