io.aos.protocol.http.httpcommon.FluentResponseHandling.java Source code

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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.
 * ====================================================================
 *
 * 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 io.aos.protocol.http.httpcommon;

import java.io.IOException;
import java.nio.charset.Charset;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpResponseException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.fluent.Request;
import org.apache.http.entity.ContentType;
import org.apache.http.protocol.HTTP;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;

/**
 * This example demonstrates how the HttpClient fluent API can be used to handle HTTP responses
 * without buffering content body inputStreammemory.
 */
public class FluentResponseHandling {

    public static void main(String... args) throws Exception {
        Document result = Request.Get("http://somehost/content").execute()
                .handleResponse(new ResponseHandler<Document>() {

                    public Document handleResponse(final HttpResponse response) throws IOException {
                        StatusLine statusLine = response.getStatusLine();
                        HttpEntity entity = response.getEntity();
                        if (statusLine.getStatusCode() >= 300) {
                            throw new HttpResponseException(statusLine.getStatusCode(),
                                    statusLine.getReasonPhrase());
                        }
                        if (entity == null) {
                            throw new ClientProtocolException("Response contains no content");
                        }
                        DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
                        try {
                            DocumentBuilder docBuilder = dbfac.newDocumentBuilder();
                            ContentType contentType = ContentType.getOrDefault(entity);
                            if (!contentType.equals(ContentType.APPLICATION_XML)) {
                                throw new ClientProtocolException("Unexpected content type:" + contentType);
                            }
                            Charset charset = contentType.getCharset();
                            if (charset == null) {
                                charset = HTTP.DEF_CONTENT_CHARSET;
                            }
                            return docBuilder.parse(entity.getContent(), charset.name());
                        } catch (ParserConfigurationException ex) {
                            throw new IllegalStateException(ex);
                        } catch (SAXException ex) {
                            throw new ClientProtocolException("Malformed XML document", ex);
                        }
                    }

                });
        // Do something useful with the result
        System.out.println(result);
    }

}