httpproxy.java

AsyncServer asyncServer = new AsyncServer();
AsyncHttpServer httpServer = new AsyncHttpServer();
AsyncHttpClient httpClient = new AsyncHttpClient(asyncServer);

httpServer.get(".*", new HttpServerRequestCallback() {
    @Override
    public void onRequest(final AsyncHttpServerRequest request, final AsyncHttpServerResponse response) {
        final AsyncHttpGet proxyRequest = new AsyncHttpGet("http://remotehost/" + request.getPath());
        String remoteHost = proxyRequest.getHeaders().get("Host");
        proxyRequest.getHeaders().addAll(request.getHeaders());
        proxyRequest.getHeaders().set("Host", remoteHost);

        httpClient.executeByteBufferList(proxyRequest, new AsyncHttpClient.DownloadCallback() {
            @Override
            public void onCompleted(Exception e, final AsyncHttpResponse proxyResponse, ByteBufferList result) {
                if (e != null) {
                    response.getHeaders().addAll(proxyResponse.headers());
                    response.code(proxyResponse.code());
                    response.end();
                    return;
                }

                // do some result transformations

                final int contentLength = result.remaining();
                final String contentType = proxyResponse.headers().get("Content-Type");
                response.getHeaders().addAll(proxyResponse.headers());
                response.getHeaders().set("Content-Length", Integer.toString(contentLength));
                response.setContentType(contentType);
                response.code(proxyResponse.code());

                // XXX: this leads to 100% CPU consumption on large content (> 1 MB)
                /*
                response.write(result);
                response.end();
                */
                
                // XXX: this works OK
                Util.writeAll(response, result, new CompletedCallback() {
                    @Override
                    public void onCompleted(Exception ex) {
                        response.end();
                    }
                });
            }
        });
    }
});

httpServer.listen(asyncServer, 0);