java 7-nio异步I/O-将来式和回调式

java7中三个异步通道

1.AsynchronousFileChannle:用于文件I/O

2.AsynchronousSockeChannle:用于套接字I/O,支持连接超时

3.AsynchronousServerSocketChannle:用于套接字接收异步连接

一.将来式

试用场景：需要读取文件的过程中还要做其他的事情。

　　

代码演示：

public static void main(String[] args) {
        Path path = Paths.get("C:\\Users\\Administrator\\Desktop\\api\\Java程序员修炼之道.pdf");
        try {
            AsynchronousFileChannel asynchronousFileChannel = AsynchronousFileChannel.open(path);
            ByteBuffer buffer = ByteBuffer.allocate(100_000_0);
            Future<Integer> result = asynchronousFileChannel.read(buffer, 0);
            //do something
            while (!result.isDone()) {
                System.out.println("test");
            }
            //结果
            Integer byteLen = result.get();
            System.out.println("bytes read="+byteLen);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }

二.回调式

　　试用场景：在I/O操作刚一成功或一失败时，需要马上采取行动，此时需要回调式I/O操作

代码：

public static void main(String[] args) {
        Path file = Paths.get("C:\\Users\\Administrator\\Desktop\\api\\Java程序员修炼之道.pdf");
        try {
            ByteBuffer buffer = ByteBuffer.allocate(100_000);
            AsynchronousFileChannel channle = AsynchronousFileChannel.open(file);
            channle.read(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {

                @Override
                public void completed(Integer result, ByteBuffer attachment) {
                    System.out.println("bytes read="+result);
                }

                @Override
                public void failed(Throwable exc, ByteBuffer attachment) {
                    System.out.println("test"+exc.getMessage());
                }
            });
        } catch (IOException e) {
            e.printStackTrace();
        }
    }