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/*
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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.
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 * This software consists of voluntary contributions made by many
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package org.apache.http.nio.client.methods;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;

import org.apache.http.Header;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.FileEntity;
import org.apache.http.nio.ContentDecoder;
import org.apache.http.nio.ContentDecoderChannel;
import org.apache.http.nio.FileContentDecoder;
import org.apache.http.nio.IOControl;
import org.apache.http.nio.protocol.AbstractAsyncResponseConsumer;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.Asserts;

/**
 * {@link org.apache.http.nio.protocol.HttpAsyncResponseConsumer} implementation that
 * streams content entity enclosed in an HTTP response directly into a file
 * without an intermediate in-memory buffer.
 * 

* This consumer can be useful for file downloads. * * @since 4.0 */ public abstract class ZeroCopyConsumer extends AbstractAsyncResponseConsumer { private final File file; private final RandomAccessFile accessfile; private HttpResponse response; private ContentType contentType; private Header contentEncoding; private FileChannel fileChannel; private long idx = -1; public ZeroCopyConsumer(final File file) throws FileNotFoundException { super(); if (file == null) { throw new IllegalArgumentException("File may nor be null"); } this.file = file; this.accessfile = new RandomAccessFile(this.file, "rw"); } @Override protected void onResponseReceived(final HttpResponse response) { this.response = response; } @Override protected void onEntityEnclosed( final HttpEntity entity, final ContentType contentType) throws IOException { this.contentType = contentType; this.contentEncoding = entity.getContentEncoding(); this.fileChannel = this.accessfile.getChannel(); this.idx = 0; } @Override protected void onContentReceived( final ContentDecoder decoder, final IOControl ioctrl) throws IOException { Asserts.notNull(this.fileChannel, "File channel"); final long transferred; if (decoder instanceof FileContentDecoder) { transferred = ((FileContentDecoder)decoder).transfer( this.fileChannel, this.idx, Integer.MAX_VALUE); } else { transferred = this.fileChannel.transferFrom( new ContentDecoderChannel(decoder), this.idx, Integer.MAX_VALUE); } if (transferred > 0) { this.idx += transferred; } if (decoder.isCompleted()) { this.fileChannel.close(); } } /** * Invoked to process received file. * * @param response original response head. * @param file file containing response content. * @param contentType the cotnent type. * @return result of the response processing */ protected abstract T process( HttpResponse response, File file, ContentType contentType) throws Exception; @Override protected T buildResult(final HttpContext context) throws Exception { final FileEntity entity = new FileEntity(this.file, this.contentType); entity.setContentEncoding(this.contentEncoding); this.response.setEntity(entity); return process(this.response, this.file, this.contentType); } @Override protected void releaseResources() { try { this.accessfile.close(); } catch (final IOException ignore) { } } }





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