Java tutorial
/** * DownloadUtil.java * * Copyright 2010 Baidu.com, Inc. * * Baidu.com 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. */ package com.iwgame.iwcloud.baidu.task.util; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; import org.apache.commons.lang.ArrayUtils; import org.apache.log4j.Logger; import com.iwgame.iwcloud.baidu.task.core.ClientInternalException; /** * * * * @ * @ ??? * @ 1.0 * @ wujunjie@iwgame.com * @2012-6-28 ?08:01:39 */ public class DownloadUtil { private static final Logger logger = Logger.getLogger(DownloadUtil.class); private static final int BUFFER_SIZE = 1024 * 16; private static final int MATERIAL_SIZE = 1024 * 30; private static final int CONNECT_TIMEOUT = 6000; private static final int READ_TIMEOUT = 6000; private static final int MAX_SIZE = 1024 * 1024 * 50; private static final int MIN_SIZE = 5; /** * * url * @param strUrl * The Url to be downloaded. * @return The file content as byte array. * @throws IOException */ public static byte[] downloadFile(String strUrl) throws IOException { return downloadFile(strUrl, CONNECT_TIMEOUT, READ_TIMEOUT, MAX_SIZE); } /** * url * @param strUrl * The Url to be downloaded. * @param connectTimeout * Connect timeout in milliseconds. * @param readTimeout * Read timeout in milliseconds. * @param maxFileSize * Max file size in BYTE. * @return The file content as byte array. */ public static byte[] downloadFile(String strUrl, int connectTimeout, int readTimeout, int maxFileSize) throws IOException { InputStream in = null; try { URL url = new URL(strUrl); // URL? URLConnection ucon = url.openConnection(); ucon.setConnectTimeout(connectTimeout); ucon.setReadTimeout(readTimeout); ucon.connect(); if (ucon.getContentLength() > maxFileSize) { String msg = "File " + strUrl + " size [" + ucon.getContentLength() + "] too large, download stoped."; logger.error(msg); throw new ClientInternalException(msg); } if (ucon instanceof HttpURLConnection) { HttpURLConnection httpCon = (HttpURLConnection) ucon; if (httpCon.getResponseCode() > 399) { String msg = "Failed to download file " + strUrl + " server response " + httpCon.getResponseMessage(); logger.error(msg); throw new ClientInternalException(msg); } } in = ucon.getInputStream(); // ? byte[] byteBuf = new byte[BUFFER_SIZE]; byte[] ret = null; int count, total = 0; // ?? while ((count = in.read(byteBuf, total, BUFFER_SIZE - total)) > 0) { total += count; if (total + 124 >= BUFFER_SIZE) break; } if (total < BUFFER_SIZE - 124) { ret = ArrayUtils.subarray(byteBuf, 0, total); } else { ByteArrayOutputStream bos = new ByteArrayOutputStream(MATERIAL_SIZE); count = total; total = 0; do { bos.write(byteBuf, 0, count); total += count; if (total > maxFileSize) { String msg = "File " + strUrl + " size exceed [" + maxFileSize + "] download stoped."; logger.error(msg); throw new ClientInternalException(msg); } } while ((count = in.read(byteBuf)) > 0); ret = bos.toByteArray(); } if (ret.length < MIN_SIZE) { String msg = "File " + strUrl + " size [" + maxFileSize + "] too small."; logger.error(msg); throw new ClientInternalException(msg); } return ret; } catch (IOException e) { String msg = "Failed to download file " + strUrl + " msg=" + e.getMessage(); logger.error(msg); throw e; } finally { try { if (in != null) { in.close(); } } catch (IOException e) { logger.error("Exception while close url - ", e); throw e; } } } private DownloadUtil() { // Utility? } }