Apache HttpComponents Custom protocol interceptors通过拦截器自定义压缩

/*

 * ====================================================================

 * 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.

 * ====================================================================

 *

 * This software consists of voluntary contributions made by many

 * individuals on behalf of the Apache Software Foundation.  For more

 * information on the Apache Software Foundation, please see

 * <http://www.apache.org/>.

 *

 */



package org.apache.http.examples.client;



import java.io.IOException;



import org.apache.http.Header;

import org.apache.http.HeaderElement;

import org.apache.http.HttpEntity;

import org.apache.http.HttpException;

import org.apache.http.HttpRequest;

import org.apache.http.HttpRequestInterceptor;

import org.apache.http.HttpResponse;

import org.apache.http.HttpResponseInterceptor;

import org.apache.http.client.entity.GzipDecompressingEntity;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.impl.client.DefaultHttpClient;

import org.apache.http.protocol.HttpContext;

import org.apache.http.util.EntityUtils;



/**

 * Demonstration of the use of protocol interceptors to transparently

 * modify properties of HTTP messages sent / received by the HTTP client.

 * <p/>

 * In this particular case HTTP client is made capable of transparent content

 * GZIP compression by adding two protocol interceptors: a request interceptor

 * that adds 'Accept-Encoding: gzip' header to all outgoing requests and

 * a response interceptor that automatically expands compressed response

 * entities by wrapping them with a uncompressing decorator class. The use of

 * protocol interceptors makes content compression completely transparent to

 * the consumer of the {@link org.apache.http.client.HttpClient HttpClient}

 * interface.

 */

public class ClientGZipContentCompression {



    public final static void main(String[] args) throws Exception {

        DefaultHttpClient httpclient = new DefaultHttpClient();

        try {

            httpclient.addRequestInterceptor(new HttpRequestInterceptor() {



                public void process(

                        final HttpRequest request,

                        final HttpContext context) throws HttpException, IOException {

                    if (!request.containsHeader("Accept-Encoding")) {

                        request.addHeader("Accept-Encoding", "gzip");

                    }

                }



            });



            httpclient.addResponseInterceptor(new HttpResponseInterceptor() {



                public void process(

                        final HttpResponse response,

                        final HttpContext context) throws HttpException, IOException {

                    HttpEntity entity = response.getEntity();

                    if (entity != null) {

                        Header ceheader = entity.getContentEncoding();

                        if (ceheader != null) {

                            HeaderElement[] codecs = ceheader.getElements();

                            for (int i = 0; i < codecs.length; i++) {

                                if (codecs[i].getName().equalsIgnoreCase("gzip")) {

                                    response.setEntity(

                                            new GzipDecompressingEntity(response.getEntity()));

                                    return;

                                }

                            }

                        }

                    }

                }



            });



            HttpGet httpget = new HttpGet("http://www.apache.org/");



            // Execute HTTP request

            System.out.println("executing request " + httpget.getURI());

            HttpResponse response = httpclient.execute(httpget);



            System.out.println("----------------------------------------");

            System.out.println(response.getStatusLine());

            System.out.println(response.getLastHeader("Content-Encoding"));

            System.out.println(response.getLastHeader("Content-Length"));

            System.out.println("----------------------------------------");



            HttpEntity entity = response.getEntity();



            if (entity != null) {

                String content = EntityUtils.toString(entity);

                System.out.println(content);

                System.out.println("----------------------------------------");

                System.out.println("Uncompressed size: "+content.length());

            }



        } finally {

            // When HttpClient instance is no longer needed,

            // shut down the connection manager to ensure

            // immediate deallocation of all system resources

            httpclient.getConnectionManager().shutdown();

        }

    }



}