简单的NIO使用实例

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();
            }
        }
    }
}