Java code to list files and download files using jsp and servlet

Here is code that will read a file from a directory. Once clicked, the files will be downloaded.

The files are stored in a directory - D:/filesFolder/
Modify the path, as per your file path in  DownloadFile and in .jsp
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The servlet java file is DownloadFile.java
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package com.sandeepshabd.example;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

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

/**
 * Servlet implementation class DownloadFile
 */
public class DownloadFile extends HttpServlet implements
javax.servlet.Servlet{
private static final long serialVersionUID = 1L;
private static final int BUFSIZE = 4096;
    /**
     * Default constructor.
     */
    public DownloadFile() {
        // TODO Auto-generated constructor stub
    }

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String name = request.getParameter("fileName");
if(name==null || name.length()==0)
{
//DO NOTHING
}else
{
startDownload(response,name);
}
}



void startDownload(HttpServletResponse response,String name)
{

String filePath = "D://filesFolder//"+name;
File file = new File(filePath);
        int length   = 0;
        ServletOutputStream outStream;
try {
outStream = response.getOutputStream();

       ServletContext context  = getServletConfig().getServletContext();
       String mimetype = context.getMimeType(filePath);
     
       // sets response content type
       if (mimetype == null) {
           mimetype = "application/octet-stream";
       }
       response.setContentType(mimetype);
       response.setContentLength((int)file.length());
       String fileName = (new File(filePath)).getName();
     
       // sets HTTP header
       response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
     
       byte[] byteBuffer = new byte[BUFSIZE];
       DataInputStream in;
try {
in = new DataInputStream(new FileInputStream(file));        // reads the file's bytes and writes them to the response stream
       try {
while ((in != null) && ((length = in.read(byteBuffer)) != -1))
{
   outStream.write(byteBuffer,0,length);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
     
       in.close();
       outStream.close();
     
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}

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

}

---------------------------------- files.jsp under webcontent---------------------------------------------

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

    pageEncoding="ISO-8859-1"%>

Directories

<%

String root="D://filesFolder//";

java.io.File file;

java.io.File dir = new java.io.File(root);

String[] list = dir.list();

if (list.length > 0) {

for (int i = 0; i < list.length; i++) {

  file = new java.io.File(root + list[i]);

  if (file!= null && !file.isDirectory() ) {

  %>

 

<%=list[i]%>

  <%

     }

  }

}

%>

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Download war file at -

https://www.box.net/shared/1u4nk2mgwm7jio46u1bn