com.redblackit.web.server.EchoServlet.java Source code

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Here is the source code for com.redblackit.web.server.EchoServlet.java

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/*
 * Copyright 2002-2011 the original author or authors, or Red-Black IT Ltd, as appropriate.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.redblackit.web.server;

import java.io.IOException;
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.apache.log4j.Logger;
import org.springframework.util.FileCopyUtils;

/**
 * @author djnorth
 * 
 *         Simple servlet that echos the request back to the client, with
 *         requested URL in the Location header, and status code 200. This can
 *         serve as a test servlet, or a keep-alive/ping for the client to use.
 */
public class EchoServlet extends HttpServlet {

    private Logger logger = Logger.getLogger("web.server");

    /**
     * Serialization stuff
     */
    private static final long serialVersionUID = 1L;

    /**
     * Use our common echo
     * 
     * @param req
     * @param resp
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doEcho(req, resp, "GET");
    }

    /**
     * Use our common echo
     * 
     * @param req
     * @param resp
     * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doEcho(req, resp, "PUT");
    }

    /**
     * Use our common echo
     * 
     * @param req
     * @param resp
     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doEcho(req, resp, "POST");
    }

    /**
     * Use our common echo
     * 
     * @param req
     * @param resp
     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doEcho(req, resp, "DELETE");
    }

    /**
     * Use our common echo
     * 
     * @param req
     * @param resp
     * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    @Override
    protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doEcho(req, resp, "HEAD");
    }

    /**
     * doEcho
     * 
     * <ul>
     * <li>Log method, URL, headers, body</li>
     * <li>Replicate request headers, except for setting location to received
     * URL</li>
     * <li>Replicate request body in response</li>
     * </ul>
     * 
     * @param req
     * @param resp
     * @param method
     */
    @SuppressWarnings("rawtypes")
    private void doEcho(HttpServletRequest req, HttpServletResponse resp, String method) throws IOException {
        String reqURI = req.getRequestURI();
        logger.debug(this.getClass().getName() + ":" + method + " - " + reqURI);

        for (Enumeration hdrse = req.getHeaderNames(); hdrse.hasMoreElements();) {
            String headerName = (String) hdrse.nextElement();
            int hnct = 0;
            for (Enumeration hdre = req.getHeaders(headerName); hdre.hasMoreElements();) {
                String headerValue = (String) hdre.nextElement();
                logger.debug(
                        this.getClass().getName() + ":  header[" + headerName + "," + hnct + "]=" + headerValue);
                if (!headerName.equals("Location")) {
                    resp.addHeader(headerName, headerValue);
                }
                hnct++;
            }

            if (hnct == 0) {
                resp.setHeader(headerName, "");
                logger.info(this.getClass().getName() + ":  header[" + headerName + "," + hnct + "]='' (empty)");
            }
        }

        resp.setHeader("Location", reqURI);
        resp.setStatus(HttpServletResponse.SC_OK);

        if (req.getContentLength() > 0 && !(method.equals("HEAD") || method.equals("DELETE"))) {
            String body = FileCopyUtils.copyToString(req.getReader());
            logger.debug(this.getClass().getName() + ":  body>>\n" + body + "\nbody<<");
            FileCopyUtils.copy(body, resp.getWriter());
            resp.flushBuffer();
            resp.setContentLength(req.getContentLength());
        } else {
            logger.debug(this.getClass().getName() + ":  body is empty");
            resp.setContentLength(0);
        }

    }
}