com.woonoz.proxy.servlet.HttpRequestHandler Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of proxy Show documentation
Make your GWT client to access another domain's services
There is a newer version: 1.0.4
/*
 * Copyright 2010 Woonoz S.A.S.
 * 
 * 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 com.woonoz.proxy.servlet;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.Enumeration;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.util.EntityUtils;

public abstract class HttpRequestHandler {

	private static final Log logger = LogFactory.getLog("com.woonoz.proxy.servlet");
	private final HttpServletRequest request;
	private final HttpServletResponse response;
	private final URL targetServer;
	private final HttpClient client;
	
	public HttpRequestHandler(HttpServletRequest request, HttpServletResponse response, URL targetServer, HttpClient client) {
		this.request = request;
		this.response = response;
		this.targetServer = targetServer;
		this.client = client;
	}
	
	protected abstract HttpRequestBase createHttpRequestBase(URI targetUri);
	
	protected HttpRequestBase createHttpCommand(final URI targetUri,
			ClientHeadersHandler clientHeadersHandler)
			throws URISyntaxException, InvalidCookieException,
			MalformedURLException, FileUploadException, IOException {
		HttpRequestBase httpRequestBase = createHttpRequestBase(targetUri);
		copyHeaders(getRequest(), httpRequestBase, clientHeadersHandler);
		return httpRequestBase;
	}
	protected ClientHeadersHandler createClientHeadersHandler(final UrlRewriter urlRewriter) {
		return new ClientHeadersHandler(urlRewriter);
	}
	
	public void execute() {
		UrlRewriter urlRewriter = new UrlRewriterImpl(request, targetServer);
		ClientHeadersHandler clientHeadersHandler = createClientHeadersHandler(urlRewriter);
		ServerHeadersHandler serverHeadersHandler = new ServerHeadersHandler(urlRewriter);
		HttpRequestBase httpCommand = null;
		try {
			final URI targetUri = urlRewriter.rewriteUri(new URI(request.getRequestURL().toString()));
			httpCommand = createHttpCommand(targetUri, clientHeadersHandler);
			performHttpRequest(httpCommand, response, serverHeadersHandler);
		} catch (URISyntaxException e) {
			handleException(httpCommand, e);
		} catch (IOException e) {
			handleException(httpCommand, e);
		} catch (InvalidCookieException e) {
			handleException(httpCommand, e);
		} catch (FileUploadException e) {
			handleException(httpCommand, e);
		} catch (RuntimeException e ) {
			handleException(httpCommand, e);
		} finally {
			
			try {
				response.getOutputStream().flush();
			} catch (IOException e) {
				logger.error("Exception flushing OutputStream ", e);
			}
		}
	}

	private void handleException(HttpRequestBase httpCommand, Exception e) {
		logger.error("Exception handling httpCommand " + httpCommand, e);
		if (httpCommand != null) {
			httpCommand.abort();
		}
	}
	
	protected HttpServletRequest getRequest() {
		return request;
	}
	
	protected HttpServletResponse getResponse() {
		return response;
	}
	
	protected void copyHeaders(final HttpResponse from, final HttpServletResponse to, ServerHeadersHandler serverHeadersHandler) throws URISyntaxException, MalformedURLException{
		for (final Header header: from.getAllHeaders()) {
			final String modifiedValue = serverHeadersHandler.handleHeader(header.getName(), header.getValue());
			if (modifiedValue != null) {
				to.addHeader(header.getName(), modifiedValue);
			}
		}
	}
	
	protected void copyHeaders(final HttpServletRequest from, final HttpRequestBase to, ClientHeadersHandler clientHeadersHandler) throws URISyntaxException, MalformedURLException {
		Enumeration enumerationOfHeaderNames = from.getHeaderNames();
        while (enumerationOfHeaderNames.hasMoreElements()) {
            final String headerName = (String)enumerationOfHeaderNames.nextElement();
            Enumeration enumerationOfHeaderValues = from.getHeaders(headerName);
            while (enumerationOfHeaderValues.hasMoreElements()) {
            	final String headerValue = (String) enumerationOfHeaderValues.nextElement();
                final String modifiedValue = clientHeadersHandler.handleHeader(headerName, headerValue);
                if (modifiedValue != null) {
                	to.addHeader(headerName, modifiedValue);
                }
            }
        }
	}

	private void performHttpRequest(HttpRequestBase requestToServer, HttpServletResponse responseToClient, ServerHeadersHandler serverHeadersHandler) throws IOException, URISyntaxException {
		HttpResponse responseFromServer = client.execute(requestToServer);
		responseToClient.setStatus(responseFromServer.getStatusLine().getStatusCode());
		copyHeaders(responseFromServer, responseToClient, serverHeadersHandler);
		HttpEntity entity = responseFromServer.getEntity();
		if (entity != null) {
			try {
				entity.writeTo(responseToClient.getOutputStream());
			} finally {
				EntityUtils.consume(entity);
			}
		}
	}
}