Compressed output

The Java servlet below demonstrates how to use compressed output from servlets. You can compress big chunks of data before sending and they will be decompressed on the fly in the browser.

Any browser supports, by default, different file formats. The most known and usable are gif and jpg of course. But browsers can also support gzip files, and in your servlets, you can detect which formats are supported. So check compression support by analyzing the request header and use Java's GZIP support for data compression.

 

import java.io.*;
import java.util.zip.*;
import java.lang.*;

import javax.servlet.*;
import javax.servlet.http.*;
public class GzipServlet extends HttpServlet {

public void doGet (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
    doPost(req,res);
}

public void doPost (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{

    String encoding=req.getHeader("Accept-Encoding");
    boolean canGzip=false;

    if (encoding!=null)
        if (encoding.indexOf("gzip")>=0)
            canGzip=true;

    if (canGzip)
    {
        res.setHeader("Content-Encoding","gzip");
        OutputStream o=res.getOutputStream();
        GZIPOutputStream gz=new GZIPOutputStream(o);

        String bigStuff="";
        bigStuff+="<html>";
        bigStuff+="<br>this was compressed";
        bigStuff+="</html>";

        gz.write(bigStuff.getBytes());
        gz.close();
        o.close();

    }
    else // no compression
    {
        res.setContentType("text/html");
        PrintWriter out=res.getWriter();

        out.println("<html>");
        out.println("<br>no compression here");
        out.println("</html>");

        out.flush();
        out.close();
      }
}

}
 


 

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