Tags: How to , J2EE

Technology world moving fast as a speed of light. Its getting change day by day. Web application is build under the MVC ( Model-View-Controller) model. Colleges still using servlet in study. In below article we'll discuss how you can manage your web application to upload files.

Required .jar files

• commons-io-2.0.jar ( http://commons.apache.org/io/download_io.cgi )
• commons-fileupload-1.2.2.jar ( http://commons.apache.org/fileupload/download_fileupload.cgi )

import bean.setNotification;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.FilenameUtils;

All above packages you have to import in you servlet. Below code is for file upload in servlet. File upload directory is "/upload/"

List fileItemsList = null;
float filesize = 0;
String _fileLink;
String _fileName = null;
String _uploadDir = getServletContext().getRealPath("/upload/");
//Change upload with your directory
HttpSession session = request.getSession(true);
try {
 if (ServletFileUpload.isMultipartContent(request)) {
 ServletFileUpload servletFileUpload = new ServletFileUpload(new DiskFileItemFactory());
       try {
        fileItemsList = servletFileUpload.parseRequest(request);
       } catch (FileUploadException ex) {
        Logger.getLogger(FileUploadExample.class.getName()).log(Level.SEVERE, null, ex);
        //Change above line replace FileUploadExample with your file name
           }
           String optionalFileName = "";
           FileItem fileItem = null;

           Iterator it = fileItemsList.iterator();
           while (it.hasNext()) {
           FileItem fileItemTemp = (FileItem) it.next();
            if (fileItemTemp.isFormField()) {
               if (fileItemTemp.getFieldName().equals("filename")) {
                  optionalFileName = fileItemTemp.getString();
               }
             /*
             * If you want to pass some other data from JSP page. You can access then in this way.
             * For each field you have do create if like below.
             * if (fileItemTemp.getFieldName().equals("Name of other field like:Firstname")) {
             * String Firstname = fileItemTemp.getString();
             * }
             */
            } else {
                  fileItem = fileItemTemp;
            }
         }
         if (fileItem != null) {
           long size_long = fileItem.getSize();
           filesize = size_long / 1024;
           filesize = filesize / 1000;
           //If you want to limit the file size. Here 30MB file size is allowed you can change it
           if (filesize > 30.0) {
           //Pass error message in session.
           setNotification _sN = new setNotification();
           _sN.setError("File size can't be more than 30MB");
           session.setAttribute("error", _sN);
           } else {
           _fileName = fileItem.getName();
           if (fileItem.getSize() > 0) {
              if (optionalFileName.trim().equals("")) {
                _fileName = FilenameUtils.getName(_fileName);
              } else {
                _fileName = optionalFileName;
              }
               _fileLink = "../upload/" + _fileName;
               try {
                File file = new File(new File(_uploadDir + "/"), fileItem.getName());
                fileItem.write(file);
               } catch (Exception e) {
                e.printStackTrace();
               }
               setNotification _sN = new setNotification();
               _sN.setError("File Uploaded to : " + _fileLink + "");
               session.setAttribute("error", _sN);
                }
               }
              }
             String referer = request.getHeader("Referer");
            response.sendRedirect(referer);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            out.close();
        }

Now notification class to shows the message to users. Use the below code.

public class setNotification {
    private String Error="";
    public String getError() {
        return Error;
    }
    public void setError(String Error) {
        this.Error = Error;
    }
}

The JSP file. Change the servlet name in action (form). Change package import bean.setNotification.

<%@page import="bean.setNotification"%>
<%
            setNotification _sN = new setNotification();
            if (session.getAttribute("error") != null) {
                _sN = (setNotification) session.getAttribute("error");
            }

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>File Upload Example</title>
        <link type="text/css" href="css/bundle.css" rel="StyleSheet"/>
    </head>
    <body>
        <center>
            <div class="signal_box" style="width: 400px;height: 150px">
                <div class="head">File Upload - javaQuery.com</div>
                <form action="FileUploadExample" method="post"  enctype="multipart/form-data">
                <input type="file" name="myFile"/><br/>
                <input type="submit" value="Upload it"/>
                </form>
                <br/>
                <%=_sN.getError()%>
                <%_sN.setError("");%>
            </div>
        </center>
    </body>
</html>

So this is file upload example in servlet.....

Tags: How to , J2EE