import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.zip.GZIPInputStream;

/**
 * @author Julius Davies
 * @author http://juliusdavies.ca/
 * @since 22-Mar-2006
 */
public class GZIPServlet extends HttpServlet
{
	public void doPost( HttpServletRequest req, HttpServletResponse res )
	      throws IOException
	{
		// This servlet just unzips a POST with gzip Content-Encoding,
		// prints off the first 4KB (unzipped) in the response, and
		// reports the total unzipped size.
		
		res.setContentType( "text/plain" );
		res.setCharacterEncoding( "UTF-8" );
		PrintWriter writer = res.getWriter();

		String contentEncoding = req.getHeader( "Content-Encoding" );
		boolean isGzip = false;
		if ( contentEncoding != null )
		{
			isGzip = "gzip".equalsIgnoreCase( contentEncoding.trim() );
		}
		if ( isGzip )
		{
			InputStream in = req.getInputStream();
			in = new BufferedInputStream( in );
			in = new GZIPInputStream( in );

			StringBuffer buf = new StringBuffer( 4096 );
			int c = in.read();
			int count = 0;
			while ( c >= 0 )
			{
				count++;
				byte b = (byte) c;
				if ( count <= 4096 )
				{
					buf.append( (char) b );
				}
				c = in.read();
			}

			writer.println( "First 4KB: " );
			writer.println( "-------------------------------------------" );
			writer.println( buf.toString() );
			writer.println( "-------------------------------------------" );
			writer.println( "Content unzipped to " + count + " bytes." );
		}
		else
		{
			writer.println( "Content-Encoding is not gzip!" );
			writer.println( "-------------------------------------------" );
			writer.println( "Content-Encoding: [" + contentEncoding + "]" );
		}

		writer.close();
	}


}