org.apache.hadoop.hdfsproxy.ProxyForwardServlet.java Source code

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Here is the source code for org.apache.hadoop.hdfsproxy.ProxyForwardServlet.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.hdfsproxy;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;

/**
 * 
 *
 */
public class ProxyForwardServlet extends HttpServlet {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private static Configuration configuration = null;
    public static final Log LOG = LogFactory.getLog(ProxyForwardServlet.class);

    /** {@inheritDoc} */
    @Override
    public void init() throws ServletException {
        ServletContext context = getServletContext();
        configuration = (Configuration) context.getAttribute("org.apache.hadoop.hdfsproxy.conf");
    }

    /** {@inheritDoc} */
    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        String hostname = request.getServerName();

        String version = configuration.get(hostname);
        if (version == null) {
            // extract from hostname directly
            String[] strs = hostname.split("[-\\.]");
            version = "/" + strs[0];
        }

        ServletContext curContext = getServletContext();
        ServletContext dstContext = curContext.getContext(version);

        // avoid infinite forwarding.
        if (dstContext == null || "HDFS Proxy Forward".equals(dstContext.getServletContextName())) {
            LOG.error("Context (" + version + ".war) non-exist or restricted from access");
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }
        LOG.debug("Request to " + hostname + " is forwarded to version " + version);
        forwardRequest(request, response, dstContext, request.getServletPath());

    }

    /** {@inheritDoc} */
    public void forwardRequest(HttpServletRequest request, HttpServletResponse response, ServletContext context,
            String pathInfo) throws IOException, ServletException {
        String path = buildForwardPath(request, pathInfo);
        RequestDispatcher dispatcher = context.getRequestDispatcher(path);
        if (dispatcher == null) {
            LOG.info("There was no such dispatcher: " + path);
            response.sendError(HttpServletResponse.SC_NO_CONTENT);
            return;
        }
        dispatcher.forward(request, response);
    }

    /** {@inheritDoc} */
    protected String buildForwardPath(HttpServletRequest request, String pathInfo) {
        String path = pathInfo;
        if (request.getPathInfo() != null) {
            path += request.getPathInfo();
        }
        if (request.getQueryString() != null) {
            path += "?" + request.getQueryString();
        }
        return path;
    }
}