How To Modify The Raw XML message of an Outbound CXF Request?

I had this problem as well today. After much weeping and gnashing of teeth, I was able to alter the StreamInterceptor class in the configuration_interceptor demo that comes with the CXF source:

OutputStream os = message.getContent(OutputStream.class);
CachedStream cs = new CachedStream();
message.setContent(OutputStream.class, cs);

message.getInterceptorChain().doIntercept(message);

try {
    cs.flush();
    CachedOutputStream csnew = (CachedOutputStream) message.getContent(OutputStream.class);

    String soapMessage = IOUtils.toString(csnew.getInputStream());
    ...

The soapMessage variable will contain the complete SOAP message. You should be able to manipulate the soap message, flush it to an output stream and do a message.setContent(OutputStream.class... call to put your modifications on the message. This comes with no warranty, since I'm pretty new to CXF myself!

Note: CachedStream is a private class in the StreamInterceptor class. Don't forget to configure your interceptor to run in the PRE_STREAM phase so that the SOAP interceptors have a chance to write the SOAP message.

Based on the first comment, I created an abstract class which can easily be used to change the whole soap envelope.

Just in case someone wants a ready-to-use code part.

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.commons.io.IOUtils;
import org.apache.cxf.binding.soap.interceptor.SoapPreProtocolOutInterceptor;
import org.apache.cxf.io.CachedOutputStream;
import org.apache.cxf.message.Message;
import org.apache.cxf.phase.AbstractPhaseInterceptor;
import org.apache.cxf.phase.Phase;
import org.apache.log4j.Logger;

/**
 * http://www.mastertheboss.com/jboss-web-services/apache-cxf-interceptors
 * http://stackoverflow.com/questions/6915428/how-to-modify-the-raw-xml-message-of-an-outbound-cxf-request
 * 
 */
public abstract class MessageChangeInterceptor extends AbstractPhaseInterceptor<Message> {

    public MessageChangeInterceptor() {
        super(Phase.PRE_STREAM);
        addBefore(SoapPreProtocolOutInterceptor.class.getName());
    }

    protected abstract Logger getLogger();

    protected abstract String changeOutboundMessage(String currentEnvelope);

    protected abstract String changeInboundMessage(String currentEnvelope);

    public void handleMessage(Message message) {
        boolean isOutbound = false;
        isOutbound = message == message.getExchange().getOutMessage()
                || message == message.getExchange().getOutFaultMessage();

        if (isOutbound) {
            OutputStream os = message.getContent(OutputStream.class);

            CachedStream cs = new CachedStream();
            message.setContent(OutputStream.class, cs);

            message.getInterceptorChain().doIntercept(message);

            try {
                cs.flush();
                IOUtils.closeQuietly(cs);
                CachedOutputStream csnew = (CachedOutputStream) message.getContent(OutputStream.class);

                String currentEnvelopeMessage = IOUtils.toString(csnew.getInputStream(), "UTF-8");
                csnew.flush();
                IOUtils.closeQuietly(csnew);

                if (getLogger().isDebugEnabled()) {
                    getLogger().debug("Outbound message: " + currentEnvelopeMessage);
                }

                String res = changeOutboundMessage(currentEnvelopeMessage);
                if (res != null) {
                    if (getLogger().isDebugEnabled()) {
                        getLogger().debug("Outbound message has been changed: " + res);
                    }
                }
                res = res != null ? res : currentEnvelopeMessage;

                InputStream replaceInStream = IOUtils.toInputStream(res, "UTF-8");

                IOUtils.copy(replaceInStream, os);
                replaceInStream.close();
                IOUtils.closeQuietly(replaceInStream);

                os.flush();
                message.setContent(OutputStream.class, os);
                IOUtils.closeQuietly(os);

            } catch (IOException ioe) {
                getLogger().warn("Unable to perform change.", ioe);
                throw new RuntimeException(ioe);
            }
        } else {
            try {
                InputStream is = message.getContent(InputStream.class);
                String currentEnvelopeMessage = IOUtils.toString(is, "UTF-8");
                IOUtils.closeQuietly(is);

                if (getLogger().isDebugEnabled()) {
                    getLogger().debug("Inbound message: " + currentEnvelopeMessage);
                }

                String res = changeInboundMessage(currentEnvelopeMessage);
                if (res != null) {
                    if (getLogger().isDebugEnabled()) {
                        getLogger().debug("Inbound message has been changed: " + res);
                    }
                }
                res = res != null ? res : currentEnvelopeMessage;

                is = IOUtils.toInputStream(res, "UTF-8");
                message.setContent(InputStream.class, is);
                IOUtils.closeQuietly(is);
            } catch (IOException ioe) {
                getLogger().warn("Unable to perform change.", ioe);

                throw new RuntimeException(ioe);
            }
        }
    }

    public void handleFault(Message message) {
    }

    private class CachedStream extends CachedOutputStream {
        public CachedStream() {
            super();
        }

        protected void doFlush() throws IOException {
            currentStream.flush();
        }

        protected void doClose() throws IOException {
        }

        protected void onWrite() throws IOException {
        }
    }
}