Java Servlet Programing Laungage

In this program, read data from different types of file (such as .txt, .doc, .pdf, .zip, .jar, .gif, .html) within a single servlet. This program consists of several jars.

Apache - commons- fileupload-io-1.2.2.jar (here)
Apache - commons-io-2.1.jar (here)
Acme - gef-0.12.3.jar (here)
iText - itextpdf-5.1.3.jar (here)

Servlet directory structure

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
    <servlet>
     <servlet-name>ReadFileServlet</servlet-name>
     <servlet-class>r4r.Servlet.ReadFileServlet</servlet-class>
    </servlet>
	<servlet-mapping>
        <servlet-name>ReadFileServlet</servlet-name>
        <url-pattern>/ReadFileServlet</url-pattern>
    </servlet-mapping>
	 <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

Index.jsp

<%-- 
    Document   : index.jsp
--%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
      <meta http-equiv="Content-Type"
	     content="text/html; charset=UTF-8">
        <title>r4r.co.in-servlet</title>
    </head>
    <body>
        <form>
         <h1>Access Servlet by servlet's Name!</h1>
         <a href="ReadFileServlet">ReadFileServlet</a>
        </form>
    </body>
</html>

Servlet Program

/*
 * Save as a ReadFileServlet.java
 */
package r4r.Servlet;
import java.awt.*;
import java.io.*;
import java.util.*;
import java.util.logging.*;
import java.util.zip.*;
import javax.servlet.*;
import javax.servlet.http.*;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import Acme.JPM.Encoders.GifEncoder;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.parser.PdfTextExtractor;

/**
 *
 * @author R4R
 */
public class ReadFileServlet extends HttpServlet {

 private final static int MAX_SIZE = 1 * 1024 * 1024; 
             //1 MB size

 protected void processRequest
  (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
  response.setContentType("text/html;charset=UTF-8");
  PrintWriter out = response.getWriter();
  try {
out.println("<html>");
out.println("<head>");
out.println("<title>" + getServletInfo() + "</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet ReadFileServlet at "
               + request.getContextPath() + "</h1>");
out.println("<form action=\"ReadFileServlet\" method=\
                   "POST\" enctype=\"multipart/form-data\">");
out.println("Select File:<input type=\"file\" name=\
                 "myFile\" value=\"\" width=\"60\"/><br/>");
out.println("<input type=\"submit\" value=\"Process Request\" />");
out.println("<input type=\"reset\" value=\"Reset\"/>");
out.println("</form>");
out.println("</body>");
out.println("</html>");
  } finally {
out.close();
  }
 }

 @Override
 protected void doGet
	  (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
  processRequest(request, response);
 }

 @Override
 protected void doPost
	  (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
  response.setContentType("multipart/x-mixed-replace;boundary=End");
  ServletOutputStream out = response.getOutputStream();

  try {
//check the request make from "multipart/form-data"
boolean isMultipartContent = 
	       ServletFileUpload.isMultipartContent(request);
if (isMultipartContent) {
 DiskFileItemFactory factory = new DiskFileItemFactory();
 ServletFileUpload fileUpload = new ServletFileUpload(factory);
 fileUpload.setSizeMax(MAX_SIZE);  //set size boundation

 //store the incomming request into list
 java.util.List<FileItem> items = fileUpload.parseRequest(request);
 Iterator<FileItem> it = items.listIterator();
 while (it.hasNext()) {
  FileItem fileItem = it.next();

  /*match incoming request Content type and 
  invoke appropriate method for handel request*/
  if (fileItem.getContentType().equals("text/plain") 
	  || fileItem.getContentType().equals("application/octet-stream")
 || fileItem.getContentType().equals("application/msword") 
	  || fileItem.getContentType().equals("text/html")) {
handleTextFile(out, response, fileItem);
  } else if 
	  (fileItem.getContentType().equals("application/x-zip-compressed"))
	  {
handleCompressedFile(out, response, fileItem);
  } else if (fileItem.getContentType().equals("image/gif")
	           || fileItem.getContentType().equals("image/pjpeg")
 || fileItem.getContentType().equals("image/x-png")) {
handleImageFile(out, response, fileItem);
  } else if (fileItem.getContentType().equals("application/pdf")) {
handlePdfFile(out, response, fileItem);
  } else {
response.sendError
(HttpServletResponse.SC_BAD_REQUEST, "File formate not reconized");
  }
 }
} else {
 response.sendError
 (HttpServletResponse.SC_BAD_REQUEST, "Request must be multipart");
}
  } catch (Exception ex) {
Logger.getLogger(ReadFileServlet.class.getName()).log(Level.SEVERE,
  "An Exception is generated while processing request", ex);
  } finally {
out.flush(); //free resource
out.close();
  }
 }

 @Override
 public String getServletInfo() {
  return "r4r.co.in-ReadFileServlet";
 }

 /* -- Method capable to handle plane file -- */
 private void handleTextFile
(ServletOutputStream out, HttpServletResponse response, FileItem fileItem)
throws FileNotFoundException, IOException {
  StringBuffer sb = new StringBuffer();
  FileReader fr = new FileReader(fileItem.getName()); //read incoming file
  BufferedReader br = new BufferedReader(fr, MAX_SIZE);
  int ch;
  while ((ch = br.read()) > -1) {
sb.append((char) ch); //covert into character
  }
  //send response to client browser
  response.setContentType("text/html;charset=UTF-8");
  out.println(sb.toString());
 }

 /* -- Method capable to handle compressed file -- */
 private void handleCompressedFile
(ServletOutputStream out, HttpServletResponse response, FileItem fileItem)
throws FileNotFoundException, IOException {
  StringBuffer sb = new StringBuffer();
  File compressFile = new File(fileItem.getName());

  ZipInputStream zipInStream = 
	     new ZipInputStream(new FileInputStream(compressFile));
  ZipEntry zipEntry = zipInStream.getNextEntry();
  if (zipEntry.getSize() == 0) {
out.println
("Zip folder contain more than one file, .zip folder must be Extract first");
  } else {
out.println("File name inside zip folder : <b>"
                    + zipEntry.getName() + "</b><br>");
InputStreamReader isr = new InputStreamReader(zipInStream);
char[] cs = new char[MAX_SIZE]; //make a array
while ((isr.read(cs, 0, cs.length)) > -1) {
 sb.append(cs);
}
//send response to client browser
response.setContentType("text/html;charset=UTF-8");
out.println(sb.toString());
  }
 }

 /* -- Method capable to handle image file -- */
 private void handleImageFile
	 (ServletOutputStream out, HttpServletResponse response, FileItem fileItem)
throws InterruptedException, IOException {
  Frame frame = new Frame(); //create a frame
  frame.addNotify();
  Image image = Toolkit.getDefaultToolkit().getImage(fileItem.getName());
  MediaTracker mt = new MediaTracker(frame);
  mt.addImage(image, 0);
  mt.waitForAll();

  //read valid image 
  int height = image.getHeight(frame);
  int width = image.getWidth(frame);
  if (height <= 0 || width <= 0) {
response.sendError(HttpServletResponse.SC_NO_CONTENT, "Not a valid image for read");
  }
  //image must be converted into gif format before send it on client browser
  response.setContentType("image/gif");
  GifEncoder encoder = new GifEncoder(image, out);
  encoder.encode();
 }

 /* -- Method capable to handle PDF file -- */
 private void handlePdfFile
	 (ServletOutputStream out, HttpServletResponse response, FileItem fileItem)
throws FileNotFoundException, IOException {
  File pdfFile = new File(fileItem.getName()); //get the imcoming file
  BufferedInputStream bis =
	   new BufferedInputStream(new FileInputStream(pdfFile), MAX_SIZE);
  PdfReader reader = new PdfReader(bis); //read file 
  int n = reader.getNumberOfPages();  //read number of page associated with file
  for (int i = 1; i <= n; i++) {
String string = PdfTextExtractor.getTextFromPage(reader, i);
//send response to client browser
response.setContentType("text/plain");
out.println(string);
  }
 }
}