com.janoz.usenet.support.GzipDecompressingEntity.java Source code

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Here is the source code for com.janoz.usenet.support.GzipDecompressingEntity.java

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/*******************************************************************************
 * Copyright (c) 2010 Gijs de Vries aka Janoz.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors:
 *     Gijs de Vries aka Janoz - initial API and implementation
 ******************************************************************************/
package com.janoz.usenet.support;

import java.io.IOException;
import java.io.InputStream;
import java.util.zip.GZIPInputStream;

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.entity.HttpEntityWrapper;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.HttpContext;

public class GzipDecompressingEntity extends HttpEntityWrapper {

    public GzipDecompressingEntity(final HttpEntity entity) {
        super(entity);
    }

    @Override
    public InputStream getContent() throws IOException, IllegalStateException {

        // the wrapped entity's getContent() decides about repeatability
        InputStream wrappedin = wrappedEntity.getContent();

        return new GZIPInputStream(wrappedin);
    }

    @Override
    public long getContentLength() {
        // length of ungzipped content is not known
        return -1;
    }

    public static DefaultHttpClient addTo(DefaultHttpClient httpClient) {
        httpClient.addRequestInterceptor(new HttpRequestInterceptor() {
            @Override
            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() {
            @Override
            public void process(final HttpResponse response, final HttpContext context)
                    throws HttpException, IOException {
                HttpEntity entity = response.getEntity();
                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;
                        }
                    }
                }
            }
        });

        return httpClient;
    }

}