Got funny character from compacting servlet

[Hengki Widjaja]

I've tried this:

    public void doFilter ( ServletRequest req, ServletResponse resp,
                        FilterChain chain ) throws IOException, ServletException {

        HttpServletRequest request=(HttpServletRequest) req;
        HttpServletResponse response=(HttpServletResponse) resp;
        
        boolean canCompress = false;
        
        if(request.getHeader("Accept-Encoding").contains("gzip") && compressionSize > 0) canCompress=true;
        
        if (req instanceof HttpServletRequest && canCompress) {
        	
        	
        	StringWrapper responseWrapper = new StringWrapper(response);
        	
        	chain.doFilter(req,responseWrapper);

        	ByteArrayOutputStream byteStream = new ByteArrayOutputStream();        	
        	GZIPOutputStream zipOut = new GZIPOutputStream(byteStream);        	
        	OutputStreamWriter tempOut = new OutputStreamWriter(zipOut,responseWrapper.getCharacterEncoding());

        	tempOut.write(responseWrapper.toString());

        	tempOut.close();

        	OutputStream realOut = response.getOutputStream();
        	byteStream.writeTo(realOut);
        	      
        }

        else chain.doFilter(request, response);

    }

public class StringWrapper
             extends HttpServletResponseWrapper {
  private StringWriter stringWriter;
  public StringWrapper(HttpServletResponse response) {
    super(response);
    stringWriter = new StringWriter();
  }

  public PrintWriter getWriter() {
    return(new PrintWriter(stringWriter));
  }

  public ServletOutputStream getOutputStream() {
    return(new StringOutputStream(stringWriter));
  }

  public String toString() {
    return(stringWriter.toString());
  }

  public StringBuffer getBuffer() {
    return(stringWriter.getBuffer());
  }
}

public class StringOutputStream extends ServletOutputStream {
  private StringWriter stringWriter;

  public StringOutputStream(StringWriter stringWriter) {
    this.stringWriter = stringWriter;
  }

  public void write(int c) {
    stringWriter.write(c);
  }
}

And the browser displayed some weird characters instead of a page. Help? THanks

[Tim Moores]

Any particular reason you're writing your own filter instead of using a ready-made one like http://onjava.com/onjava/2003/11/19/filters.html ?

[Hengki Widjaja]

I think the example is not complete, the GZIPResponseWrapper class is not there.

[Tim Moores]

The link to the source code is at the bottom of the page.

[Hengki Widjaja]

Thanks, I didn't see that before.

[Hengki Widjaja]

Just when everything seems to work, I got several errors pop up.
java.io.IOException: Cannot flush a closed output stream

[Deepak Bala]

Can you post the stack trace and the java file on which the exception occurs ?