public static void main(String[] args) throws Exception {

		FileInputStream finput = new FileInputStream("E://test.txt");

		FileChannel fchannel = finput.getChannel();

		ByteBuffer byteBf = ByteBuffer.allocate(1024);

		fchannel.read(byteBf);

		Charset charSet = Charset.forName("utf-8");

		byteBf.flip();

		System.out.println(charSet.decode(byteBf));

	}

/**

 * selector 只是一个通知，具体各个部分自行处理

 *

 * NIO , 不阻塞，当有东西来了就开始通知处理，不然能一直select到·

 *

 * @author hejb

 *

 */

public class Test {

	public static void main(String[] args) throws Exception {

		ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();

		// 阻塞为false

		serverSocketChannel.configureBlocking(false);

		// 绑定IP和端口

		serverSocketChannel.socket().bind(new InetSocketAddress("0.0.0.0", 8080));

		Selector selector = Selector.open();

		// 注册感兴趣事件到selector

		serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

		while (selector.select() != 0) {

			Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();

			while (iterator.hasNext()) {

				// 循选中事件

				SelectionKey selecttionKey = iterator.next();

				// 删除已经处理

				iterator.remove();

				if (selecttionKey.isAcceptable()) {

					// 返回注册该事件时的channel ，即SelectableChannel

					ServerSocketChannel channel = (ServerSocketChannel) selecttionKey.channel();

					// 有连接事件来了， 可以处理接收请求了,注意如果不进行accept，select.select()一直能轮询到东西

					// 接收后返回了个socketchannel，开始配置

					SocketChannel socketChannel = channel.accept();

					// 也配置成非阻塞处理

					socketChannel.configureBlocking(false);

					// 复用同一个selector上注册感兴趣的事件,并注册感兴趣的可读事件

					socketChannel.register(selector, selecttionKey.OP_READ);

				}

				// 如果来可以可读事件

				if (selecttionKey.isReadable()) {

					// 返回注册该事件时的channel ，即实现了SelectableChannel的

					SocketChannel socketChannel = (SocketChannel) selecttionKey.channel();

					// 后面就都是通过byteBuffer和channel来读操作了

					ByteBuffer byteBf = ByteBuffer.allocate(1024);

					socketChannel.read(byteBf);

					Charset charset = Charset.forName("utf-8");

					byteBf.flip();

					System.out.println("clinet :" + charset.decode(byteBf));

					// socket是双通道，故也可以直接返回东西了

					socketChannel.write(charset.encode("test only"));

				}

			}

		}

	}

	// 有个疑问，NIO的链接什么时候关闭呢，有文章说是在finalize方法里,待我去找找

}

public static String readFileWithoutBuffer() throws IOException {

        // BIO inputstream without buffer

        FileInputStream input = new FileInputStream("E://test.txt");

        byte[] content = new byte[1024];

        int length = input.read(content);

        input.close();

        return new String(content, 0, length);

    }

public static String readFileWithBuffer() throws IOException {

        // BIO inputstream with buffer

        FileInputStream input = new FileInputStream("E://test.txt");

        BufferedInputStream binpt = new BufferedInputStream(input);

        byte[] bufferContent = new byte[1024];

        int length = binpt.read(bufferContent);

        return new String(bufferContent, 0, length);

    }

 public synchronized int read() throws IOException {

        if (pos >= count) {

            fill(); // 如果读取大于缓存了，填充缓冲buff

            if (pos >= count)

                return -1;

        }

        return getBufIfOpen()[pos++] & 0xff;

    }