com.baidu.api.client.core.DownloadUtil.java Source code

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Here is the source code for com.baidu.api.client.core.DownloadUtil.java

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/**
 * DownloadUtil.java
 * <p>
 * Copyright @year@ @company@, Inc.
 *
 * @company@ 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:
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.baidu.api.client.core;

import org.apache.commons.lang.ArrayUtils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;

/**
 * Download file from remote server.
 *
 * @author @author@ (@author-email@)
 * @version @version@, $Date: 2011-7-22$
 */
public class DownloadUtil {

    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;

    /**
     * Download the file pointed by the url and return the content as byte array.
     *
     * @param strUrl The Url to be downloaded.
     * @return The file content as byte array.
     */
    public static byte[] downloadFile(String strUrl) {
        return downloadFile(strUrl, CONNECT_TIMEOUT, READ_TIMEOUT, MAX_SIZE);
    }

    /**
     * Download the file pointed by the url and return the content as byte array.
     *
     * @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) {
        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.";
                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();
                    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.";
                        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.";
                throw new ClientInternalException(msg);
            }
            return ret;
        } catch (IOException e) {
            String msg = "Failed to download file " + strUrl + " msg=" + e.getMessage();
            throw new ClientInternalException(msg);
        } finally {
            try {
                if (in != null)
                    in.close();
            } catch (IOException e) {
                // ?
                System.out.println("Exception while close url - " + e.getMessage());
            }
        }
    }

    private DownloadUtil() {
        // Utility, ?
    }
}