Re: Setting a response header in a Tomcat Filter

 Mr B <>
Wed, 29 Aug 2007 07:56:07 -0700
On 14 Aug, 19:30, Manish Pandit <> wrote:

On Aug 14, 1:09 am, Mr B <> wrote:

On 13 Aug, 20:36, Manish Pandit <> wrote:

On Aug 13, 4:05 am, Mr B <> wrote:

I need to set afilterin Tomcat that changes the response header
slightly. i have used afilterto try and change the header SOAPAction
to a value of ebXML:

        public void doFilter(ServletRequest request, ServletResponse
response, FilterChain chain)
                throws IOException, ServletException {
                HttpServletResponse hrs = (HttpServletResponse)response;
                hrs.setHeader("SOAPAction", "ebXML");

                chain.doFilter(request, hrs);


But the header never changes. Can I do this? If I can then any clues
as to why the header is not being changed?



Did you configure it correctly in web.xml? You might want to put debug
statements to ensure it is initialized and is being invoked.

Manish- Hide quoted text -

- Show quoted text -

Hi Manish, thanks for the reply. Yes, it is configured OK and is
working in that it manipultes the content of the response. The trouble
is that I am calling the HttpServletResponse methods SetHeader (and
also addHeader) to the response passed into thefilter, but it doesn't
matter what I do, the response header is not changed. The header value
I am trying to change is the SOAPAction header and I am trying to
change it to "ebXML" but its as though the header is read-only. Does
this make sense? If so, should I be able to change the header?


Paul- Hide quoted text -

- Show quoted text -

Hi Paul,

This is interesting! How are you verifying that the header is added or
not? How about after adding the header, verify if it is set (in thefilteritself) by calling containsHeader( ) ? That way you will know
if thefilteris even adding the header correctly or not.

Manish- Hide quoted text -

- Show quoted text -

Sorry about the delay in replying. I managed to sort my problem out,
but the SOAPAction header was a bit of a "red herring". I finally
managed to manipulte the content-length header as I needed to remove
the contents of the 200 OK status response. All works fine now. Just
to explain, I use the Reverse-via SOAP header to see whether the
request was from an external source, then I simply remove the body and
set the content-length to 0. The code is as follows:

package com.webswell.filter;

import javax.servlet.*;
import javax.servlet.http.*;

class KillGhostFilterStream extends ServletOutputStream {
    private OutputStream intStream;
    private ByteArrayOutputStream baStream;
    private boolean closed = false;

    private String text1;
    private String text2;

    public KillGhostFilterStream(OutputStream outStream, String t1,
String t2)
        intStream = outStream;
        baStream = new ByteArrayOutputStream();
        text1 = t1;
        text2 = t2;

    public void write(int i) throws {

    public void close() throws {
        if (!closed) {
            closed = true;

    public void flush() throws
        if (baStream.size() != 0) {
            if (! closed) {
                processStream(); // need to synchronize the flush!
                baStream = new ByteArrayOutputStream();

    public void processStream() throws

    public byte [] replaceContent(byte [] inBytes)
        String retVal ="";
        String firstPart="";
        String tempFind="";

        String origString = new String(inBytes);
        String srchString = (new String(inBytes)).toLowerCase();

        if ((srchString.indexOf(text1.toLowerCase()) > -1) &&
(srchString.indexOf(text2.toLowerCase()) > -1)) {
            System.out.println("I found an empty Header and an empty body!");
            return "".getBytes();

        return origString.getBytes();

class KillGhostFilterWrapper extends HttpServletResponseWrapper
    private PrintWriter tpWriter;
    private KillGhostFilterStream tpStream;

    public KillGhostFilterWrapper(ServletResponse inResp, String text1,
String text2) throws
        super((HttpServletResponse) inResp);
        tpStream = new KillGhostFilterStream(inResp.getOutputStream(),
text1, text2);
        tpWriter = new PrintWriter(tpStream);

    public ServletOutputStream getOutputStream() throws
        return tpStream;
    public PrintWriter getWriter() throws
        return tpWriter;

public final class KillGhostFilter implements Filter
    private FilterConfig filterConfig = null;

    private String searchText1 = "<SOAP-ENV:Header/>";
    private String searchText2 = "<SOAP-ENV:Body/>";

    public void doFilter(ServletRequest request, ServletResponse
response, FilterChain chain)
        throws IOException, ServletException {

        java.util.Date date = new java.util.Date();
        HttpServletRequest req = (HttpServletRequest) request;
        String rev = req.getHeader("Reverse-via");
        if ((rev!=null) )

            System.out.println(date+": "+req.getHeader("Reverse-via"));
            System.out.println(date+": "+req.getRemoteAddr());
            HttpServletResponse resp = (HttpServletResponse)response;
            KillGhostFilterWrapper myWrappedResp = new
KillGhostFilterWrapper(resp, searchText1, searchText2);
            chain.doFilter(request, myWrappedResp);

            chain.doFilter(request, response);

            //HttpServletResponse resp = (HttpServletResponse)resp;
            //KillGhostFilterWrapper myWrappedResp = new
KillGhostFilterWrapper(resp, searchText1, searchText2);
            //chain.doFilter(request, myWrappedResp);
            //myWrappedResp.setContentLength(0) ;



    public void destroy()

    public void init(FilterConfig filterConfig)
        this.filterConfig = filterConfig;

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