public class ThreadTest_2 {

    public static void main(String[] args) {

        Thread downloaderThread = null;

        for (String url : args) {

            downloaderThread = new Thread(new FileDownload(url));

            downloaderThread.start();

        }

    }

    static class FileDownload implements Runnable {

        private final String fileURL;

        public FileDownload(String fileURL) {

            this.fileURL = fileURL;

        }

        @Override

        public void run() {

            System.out.println("Downloading from " + fileURL);

            String fileBaseName = fileURL.substring(fileURL.lastIndexOf("/") + 1);

            try {

                URL url = new URL(fileURL);

                String localFileNmae = "D:\\viscent-" + fileBaseName;

                System.out.println("Saving to " + localFileNmae);

                downloadFile(url, new FileOutputStream(localFileNmae), 1024);

            } catch (Exception e) {

                e.printStackTrace();

            }

            System.out.println("Done downloading from " + fileURL);

        }

        private void downloadFile(URL url, FileOutputStream fileOutputStream, int bufSize) throws Exception {

            final HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();

            httpURLConnection.setRequestMethod("GET");

            int resonseCode = httpURLConnection.getResponseCode();
            //读通道

            ReadableByteChannel inChannel = null;
            //写通道

            WritableByteChannel outChannel = null;

            try {

                if (2 != resonseCode / 100) {

                    throw new IOException("Eroor: HTTP" + resonseCode);

                }

                if (0 == httpURLConnection.getContentLength()) {

                    System.out.println("没有内容可下载");

                }

                inChannel = Channels.newChannel(new BufferedInputStream(httpURLConnection.getInputStream()));

                outChannel = Channels.newChannel(new BufferedOutputStream(fileOutputStream));

                ByteBuffer byteBuffer = ByteBuffer.allocate(bufSize);

                while (-1 != inChannel.read(byteBuffer)) {
                    //反转状态，由写变读

                    byteBuffer.flip();

                    outChannel.write(byteBuffer);

                    byteBuffer.clear();

                }

            }finally {

                inChannel.close();

                outChannel.close();

                httpURLConnection.disconnect();

            }

        }

    }

}