java多线程网页下载代码

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import java.io.FileOutputStream; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; import java.nio.channels.Channels; import java.nio.channels.FileChannel; import java.nio.channels.ReadableByteChannel; import java.util.Calendar; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class HttpDownloader implements Callable { URLConnection connection; FileChannel outputChann; public static volatile int count = 0; public static void main(String[] args) throws Exception { ExecutorService poll = Executors.newFixedThreadPool(100); for (int i = 0; i < 100; i++) { Calendar now = Calendar.getInstance(); String fileName = "../data/" + now.get(Calendar.YEAR) + "年" + (now.get(Calendar.MONTH) + 1) + "月" + now.get(Calendar.DAY_OF_MONTH) + "日--" + i + ".txt"; poll.submit(new HttpDownloader("http://www.sina.com", (new FileOutputStream(fileName)).getChannel())); } poll.shutdown(); long start = System.currentTimeMillis(); while (!poll.isTerminated()) { Thread.sleep(1000); System.out.println("已运行" + ((System.currentTimeMillis() - start) / 1000) + "秒，" + HttpDownloader.count + "个任务还在运行"); } } public HttpDownloader(String url, FileChannel fileChannel) throws Exception { synchronized (HttpDownloader.class) { count++; } connection = (new URL(url)).openConnection(); this.outputChann = fileChannel; } @Override public String call() throws Exception { connection.connect(); InputStream inputStream = connection.getInputStream(); ReadableByteChannel rChannel = Channels.newChannel(inputStream); outputChann.transferFrom(rChannel, 0, Integer.MAX_VALUE); // System.out.println(Thread.currentThread().getName() + " completed!"); inputStream.close(); outputChann.close(); synchronized (HttpDownloader.class) { count--; } return null; } }