我的Java开发学习之旅------>Java多线程下载文件 实例

import java.io.File;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.URL;public class MulThreadDownload {public static void main(String[] args) throws Exception {String path = "http://192.168.1.100:8080/Hello/Big.exe";new MulThreadDownload().download(path, 3);}/** * 下载文件 *  * @param path *            网络文件路径 * @param threadSize *            线程数 * @throws Exception */private void download(String path, int threadSize) throws Exception {URL url = new URL(path);HttpURLConnection connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(5000);if (connection.getResponseCode() == 200) {int length = connection.getContentLength();// 获取网络文件长度File file = new File(getFileName(path));// 在本地生成一个长度与网络文件相同的文件RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");accessFile.setLength(length);accessFile.close();// 计算每条线程负责下载的数据量int block = length % threadSize == 0 ? length / threadSize : length/ threadSize + 1;for (int threadId = 0; threadId < threadSize; threadId++) {new DownloadThread(threadId, block, url, file).start();}} else {System.out.println("download fail");}}private class DownloadThread extends Thread {private int threadId;private int block;private URL url;private File file;public DownloadThread(int threadId, int block, URL url, File file) {this.threadId = threadId;this.block = block;this.url = url;this.file = file;}@Overridepublic void run() {int start = threadId * block; // 计算该线程从网络文件什么位置开始下载int end = (threadId + 1) * block - 1; // 计算下载到网络文件什么位置结束try {RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");accessFile.seek(start);  //从start开始HttpURLConnection connection = (HttpURLConnection) url.openConnection();connection.setRequestMethod("GET");connection.setConnectTimeout(5000);//设置获取资源数据的范围，从start到endconnection.setRequestProperty("Range", "bytes=" + start + "-"+ end);//注意多线程下载状态码是 206  不是200if (connection.getResponseCode() == 206) {InputStream inputStream = connection.getInputStream();byte[] buffer = new byte[1024];int len = 0;while ((len = inputStream.read(buffer)) != -1) {accessFile.write(buffer, 0, len);}accessFile.close();inputStream.close();}System.out.println("第" + (threadId + 1) + "条线程已经下载完成");} catch (Exception e) {e.printStackTrace();}}}/** * 获取文件名称 *  * @param path *            网络文件路径 * @return */private String getFileName(String path) {return path.substring(path.lastIndexOf("/") + 1);}}

==================================================================================================

  作者：欧阳鹏  欢迎转载，与人分享是进步的源泉！

  转载请保留原文地址：http://blog.csdn.net/ouyang_peng

==================================================================================================