How to make servlet for dowload image option

Suppose you have to write one serlvet, who would be give the download the image as save or open option.

This servelt should pick up the image as per the URL parameter from local drive and give the option of save or option image on your disk.

1. Make one Servlet SendImage

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SendImage extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {

private SendImageHelper sendImageHelper;

public SendImage() {
super();
sendImageHelper = new SendImageHelper();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
sendImageHelper.sendImage(getServletContext(),request,response);
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}

}
2. One java file SendImageHelper.java

package com.tgt.image.sendimage.service;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
import java.util.StringTokenizer;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SendImageHelper {

String image_name = "";
List imageTypes = new ArrayList();
List numbers = new ArrayList();
ResourceBundle props = null;
String filePath = "";

private static final int BUFSIZE = 100;
private ServletContext servletContext;

public void sendImage(ServletContext servletContext,HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
this.servletContext = servletContext;
String reqUrl = request.getRequestURL().toString();
StringTokenizer tokens = new StringTokenizer(reqUrl,"/");
int noOfTokens = tokens.countTokens();
String tokensString[] = new String[noOfTokens];
int count=0;
while(tokens.hasMoreElements()){
tokensString[count++] = (String)tokens.nextToken();
}

String folderName = tokensString[noOfTokens-2];
image_name = tokensString[noOfTokens-1];
filePath="/"+folderName+"/"+image_name;
fullFilePath = "c:/ImageFolder"+filePath;
//doShowImageOnPage(fullFilePath, request, response);
doDownload(fullFilePath, request, response);
}

private void doShowImageOnPage(String fullFilePath,HttpServletRequest request, HttpServletResponse response) throws IOException {
response.reset();
response.setHeader("Content-Disposition", "inline" );
response.setHeader("Cache-Control","no-cache");
response.setHeader("Expires","0");
response.setContentType("image/tiff");
byte[] image = getImage(fullFilePath);
OutputStream outputStream = response.getOutputStream();
outputStream.write(image);outputStream.close();
}

private void doDownload(String filePath,HttpServletRequest request, HttpServletResponse response) throws IOException {
File fileName = new File(filePath);
int length = 0;
ServletOutputStream outputStream = response.getOutputStream();
//ServletContext context = getServletConfig().getServletContext();
ServletContext context = servletContext;
String mimetype = context.getMimeType(filePath);

response.setContentType( (mimetype != null) ? mimetype : "application/octet-stream" );
response.setContentLength( (int)fileName.length() );
response.setHeader( "Content-Disposition", "attachment; filename=\"" + image_name + "\"" );

byte[] bbuf = new byte[BUFSIZE];
DataInputStream in = new DataInputStream(new FileInputStream(fileName));
while ((in != null) && ((length = in.read(bbuf)) != -1)){
outputStream.write(bbuf,0,length);
}

in.close();
outputStream.flush();
outputStream.close();
}

}