org.meteogroup.jbrotli.httpclient.apache.HttpClientExample.java Source code

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/*
 * Copyright (c) 2016 MeteoGroup Deutschland GmbH
 *
 *  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 org.meteogroup.jbrotli.httpclient.apache;

import org.apache.http.*;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;
import org.meteogroup.jbrotli.libloader.BrotliLibraryLoader;

import java.io.IOException;

public class HttpClientExample {

    private static final String BROTLI_MIME_TYPE = "br";

    private HttpRequestInterceptor httpRequestInterceptor = createHttpRequestInterceptor();

    HttpResponseInterceptor httpResponseInterceptor = createHttpResponseInterceptor();

    public String downloadFileAsString(String url) throws IOException {
        BrotliLibraryLoader.loadBrotli();
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        httpClientBuilder.addInterceptorFirst(httpRequestInterceptor);
        httpClientBuilder.addInterceptorFirst(httpResponseInterceptor);
        try (CloseableHttpClient httpClient = httpClientBuilder.build()) {
            String entity = downloadFileAsString(httpClient, url);
            if (entity != null)
                return entity;
        }
        return null;
    }

    private String downloadFileAsString(CloseableHttpClient httpClient, String url) throws IOException {
        HttpGet httpget = new HttpGet(url);
        HttpResponse response = httpClient.execute(httpget);
        HttpEntity entity = response.getEntity();
        if (entity != null) {
            return EntityUtils.toString(entity);
        }
        return null;
    }

    private HttpRequestInterceptor createHttpRequestInterceptor() {
        return new HttpRequestInterceptor() {
            @Override
            public void process(HttpRequest request, HttpContext httpContext) throws HttpException, IOException {
                if (!request.containsHeader("Accept-Encoding")) {
                    request.addHeader("Accept-Encoding", BROTLI_MIME_TYPE);
                }
            }
        };
    }

    private HttpResponseInterceptor createHttpResponseInterceptor() {
        return new HttpResponseInterceptor() {
            @Override
            public void process(HttpResponse response, HttpContext httpContext) throws HttpException, IOException {
                HttpEntity entity = response.getEntity();
                if (entity != null) {
                    Header contentEncoding = entity.getContentEncoding();
                    if (usesBrotliContentEncoding(contentEncoding)) {
                        response.setEntity(new BrotliDecompressingEntity(response.getEntity()));
                    }
                }
            }
        };
    }

    private boolean usesBrotliContentEncoding(Header contentEncoding) {
        if (contentEncoding != null) {
            for (HeaderElement codec : contentEncoding.getElements()) {
                if (BROTLI_MIME_TYPE.equalsIgnoreCase(codec.getName())) {
                    return true;
                }
            }
        }
        return false;
    }
}