If you are planning to validate a file over its size at client side only using some java script then SORRY.

Listen

Listen

Listen

You need not to be disappointed. I have many solutions

1. ActiveX control
   Write the following code in script tag in your HTML.

   function getSize()
   {
   	var myFSO = new ActiveXObject("Scripting.FileSystemObject");
   	var filepath = document.upload.file.value;
   	var thefile = myFSO.getFile(filepath);
   	var size = thefile.size;
   	alert(size + " bytes");
   }
   

   Please note this

   Use of ActiveX control is always avoided due to security reasons.
2. Java Applet – I had written a Java applet. But i’ll prefer to write a separate code for the same.
3. SWF – I haven’t tried it before. But it is a very good option.
4. .htaccess
   Write following line in your .htaccess file.

   LimitRequestBody 2097152

   Apache error log will generate this entry when you exceed this limit on a form post or get request:

   Requested content-length of 4000107 is larger than the configured limit of 2097152
   

   And it will also display this message back in the web browser:

   <h1>Request Entity Too Large</h1>

   By the way, the error number returned is 413. So, you could use a directive in your .htaccess file.

   Redirect 413 413.html

5. Best way:

Let client upload the file. Don’t write it at server end immediately. Instead,

1. Create a file progress bar who monitors how much part of a file has been uploaded.
2. Once it crosses maximum specified size limit;
   1. Leave writing
   2. Prompt the client.

Now see how to implement this logic in Java

1


Download following jars

• commons-fileupload-1.2.1
• commons-io-1.4

You will get them easily on apache sites.




2


Add following code in your java class say servlet.

import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.*;

import org.apache.commons.io.*;



3


Following line will help you to identify whether client is uploaded a file or not.

boolean isMultipart = ServletFileUpload.isMultipartContent(request);



4


If yes then first read all the values through some iterator. And check whether there is any non form field (means whether the current item is a file)

Object img = itr.next();
FileItem item = (FileItem) img;
if (!item.isFormField()){
:
}



5


Now its up to you whether you write a file on your server immediately. Or Byte by Byte. I’ll suggest for second option.

byte[] boundary = "article-stack.net".getBytes();
//byte[] boundary = new byte[1000000]; //geting hanged by defining fixed no of bytes
try{
    MultipartStream ms = new MultipartStream(item.getInputStream(),boundary,1000);

    FileOutputStream fileOut = new FileOutputStream(savedFile);
    ms.readBodyData(fileOut);
    fileOut.flush();
    fileOut.close();
}catch(Exception exp)
{
  savedFile.delete();
  exp.printStackTrace();
}



6


Its not done boss. You have to write a progress listener.

ProgressListener progressListener = new ProgressListener(){
   private long megaBytes = -1;
   public void update(long pBytesRead, long pContentLength, int pItems) {
       long mBytes = pBytesRead / 1000000;
       if (megaBytes == mBytes) {
           return;
       }
       megaBytes = mBytes;
       System.out.println("We are currently reading item " + pItems);
       if (pContentLength == -1) {
           System.out.println("So far, " + pBytesRead + " bytes have been read.");
       } else {
           System.out.println("So far, " + pBytesRead + " of " + pContentLength
                              + " bytes have been read.");
       }
   }
};

Modify the above progress listener as per your need to limit the file size.

Happy……..

Amit Gupta

Hey! this is Amit Gupta (amty). By profession, I am a Software Eng. And teaching is my passion. Sometimes I am a teacher, as you can see many technical tutorials on my site, sometimes I am a poet, And sometime just a friend of friends...