RedirectServlet.java

package br.gov.sp.tce.audesp.controller.servlet;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class RedirectServlet extends HttpServlet {

    private static final long serialVersionUID = -9073728400053939150L;

    private static final Logger logger = LoggerFactory.getLogger(RedirectServlet.class);

    @Override
    public void init() throws ServletException {
        super.init();
    }

    @Override
    public void destroy() {
        super.destroy();
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        forwardRequest("POST", request, response);
    }

    private void forwardRequest(String method, HttpServletRequest request, HttpServletResponse response) throws IOException {
        final boolean hasoutbody = (method.equals("POST"));

        try {
            logger.info("Recebendo Pacote - [contexto]");
            String path = "http://localhost:8080" + "/contexto";
            String queryString = request.getQueryString() != null ? "?" + request.getQueryString() : "";
            final URL url = new URL(path + queryString);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod(method);

            final Enumeration<String> headers = request.getHeaderNames();
            while (headers.hasMoreElements()) {
                final String header = headers.nextElement();
                final Enumeration<String> values = request.getHeaders(header);
                while (values.hasMoreElements()) {
                    final String value = values.nextElement();
                    conn.addRequestProperty(header, value);
                }
            }

            //conn.setFollowRedirects(false);  // throws AccessDenied exception
            conn.setUseCaches(false);
            conn.setDoInput(true);
            conn.setDoOutput(hasoutbody);
            logger.info("Redirecionando Para: " + url.toString());
            conn.connect();

            final byte[] buffer = new byte[16384];
            while (hasoutbody) {
                final int read = request.getInputStream().read(buffer);
                if (read <= 0) {
                    break;
                }
                conn.getOutputStream().write(buffer, 0, read);
            }

            response.setStatus(conn.getResponseCode());
            for (int i = 0;; ++i) {
                final String header = conn.getHeaderFieldKey(i);
                if (header == null) {
                    break;
                }
                final String value = conn.getHeaderField(i);
                response.setHeader(header, value);
            }

            while (true) {
                final int read = conn.getInputStream().read(buffer);
                if (read <= 0) {
                    break;
                }
                response.getOutputStream().write(buffer, 0, read);
            }
        } catch (Exception e) {
            logger.error("Erro no foward da request [contexto]", e);
        } finally {
            response.flushBuffer();
        }
    }
}