JAVA NIO 实例

       最近一直在忙着JAVA NIO的知识，花了一下午的时间，总算写出了一个可以运行的程序，废话少说，上代码！

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class NIOServer {
	
	/*标识数字*/
	private  int flag = 0;
	/*缓冲区大小*/
	private  int BLOCK = 4096;
	/*接受数据缓冲区*/
	private  ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK);
	/*发送数据缓冲区*/
	private  ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK);
	private  Selector selector;

	public NIOServer(int port) throws IOException {
		// 打开服务器套接字通道
		ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
		// 服务器配置为非阻塞
		serverSocketChannel.configureBlocking(false);
		// 检索与此通道关联的服务器套接字
		ServerSocket serverSocket = serverSocketChannel.socket();
		// 进行服务的绑定
		serverSocket.bind(new InetSocketAddress(port));
		// 通过open()方法找到Selector
		selector = Selector.open();
		// 注册到selector，等待连接
		serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
		System.out.println("Server Start----8888:");
	}


	// 监听
	private void listen() throws IOException {
		while (true) {
			// 选择一组键，并且相应的通道已经打开
			selector.select();
			// 返回此选择器的已选择键集。
			Set<SelectionKey> selectionKeys = selector.selectedKeys();
			Iterator<SelectionKey> iterator = selectionKeys.iterator();
			while (iterator.hasNext()) {		
				SelectionKey selectionKey = iterator.next();
				iterator.remove();
				handleKey(selectionKey);
			}
		}
	}

	// 处理请求
	private void handleKey(SelectionKey selectionKey) throws IOException {
		// 接受请求
		ServerSocketChannel server = null;
		SocketChannel client = null;
		String receiveText;
		String sendText;
		int count=0;
		// 测试此键的通道是否已准备好接受新的套接字连接。
		if (selectionKey.isAcceptable()) {
			// 返回为之创建此键的通道。
			server = (ServerSocketChannel) selectionKey.channel();
			// 接受到此通道套接字的连接。
			// 此方法返回的套接字通道（如果有）将处于阻塞模式。
			client = server.accept();
			// 配置为非阻塞
			client.configureBlocking(false);
			// 注册到selector，等待连接
			client.register(selector, SelectionKey.OP_READ);
		} else if (selectionKey.isReadable()) {
			// 返回为之创建此键的通道。
			client = (SocketChannel) selectionKey.channel();
			//将缓冲区清空以备下次读取
			receivebuffer.clear();
			//读取服务器发送来的数据到缓冲区中
			count = client.read(receivebuffer);	
			if (count > 0) {
				receiveText = new String( receivebuffer.array(),0,count);
				System.out.println("服务器端接受客户端数据--:"+receiveText);
				client.register(selector, SelectionKey.OP_WRITE);
			}
		} else if (selectionKey.isWritable()) {
			//将缓冲区清空以备下次写入
			sendbuffer.clear();
			// 返回为之创建此键的通道。
			client = (SocketChannel) selectionKey.channel();
			sendText="message from server--" + flag++;
			//向缓冲区中输入数据
			sendbuffer.put(sendText.getBytes());
			 //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位
			sendbuffer.flip();
			//输出到通道
			client.write(sendbuffer);
			System.out.println("服务器端向客户端发送数据--："+sendText);
			client.register(selector, SelectionKey.OP_READ);
		}
	}

	/**
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		int port = 8888;
		NIOServer server = new NIOServer(port);
		server.listen();
	}
}

 

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class NIOClient {

	/*标识数字*/
	private static int flag = 0;
	/*缓冲区大小*/
	private static int BLOCK = 4096;
	/*接受数据缓冲区*/
	private static ByteBuffer sendbuffer = ByteBuffer.allocate(BLOCK);
	/*发送数据缓冲区*/
	private static ByteBuffer receivebuffer = ByteBuffer.allocate(BLOCK);
	/*服务器端地址*/
	private final static InetSocketAddress SERVER_ADDRESS = new InetSocketAddress(
			"localhost", 1111);

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		// 打开socket通道
		SocketChannel socketChannel = SocketChannel.open();
		// 设置为非阻塞方式
		socketChannel.configureBlocking(false);
		// 打开选择器
		Selector selector = Selector.open();
		// 注册连接服务端socket动作
		socketChannel.register(selector, SelectionKey.OP_CONNECT);
		// 连接
		socketChannel.connect(SERVER_ADDRESS);
		// 分配缓冲区大小内存
		
		Set<SelectionKey> selectionKeys;
		Iterator<SelectionKey> iterator;
		SelectionKey selectionKey;
		SocketChannel client;
		String receiveText;
		String sendText;
		int count=0;

		while (true) {
			//选择一组键，其相应的通道已为 I/O 操作准备就绪。
			//此方法执行处于阻塞模式的选择操作。
			selector.select();
			//返回此选择器的已选择键集。
			selectionKeys = selector.selectedKeys();
			//System.out.println(selectionKeys.size());
			iterator = selectionKeys.iterator();
			while (iterator.hasNext()) {
				selectionKey = iterator.next();
				if (selectionKey.isConnectable()) {
					System.out.println("client connect");
					client = (SocketChannel) selectionKey.channel();
					// 判断此通道上是否正在进行连接操作。
					// 完成套接字通道的连接过程。
					if (client.isConnectionPending()) {
						client.finishConnect();
						System.out.println("完成连接!");
						sendbuffer.clear();
						sendbuffer.put("Hello,Server".getBytes());
						sendbuffer.flip();
						client.write(sendbuffer);
					}
					client.register(selector, SelectionKey.OP_READ);
				} else if (selectionKey.isReadable()) {
					client = (SocketChannel) selectionKey.channel();
					//将缓冲区清空以备下次读取
					receivebuffer.clear();
					//读取服务器发送来的数据到缓冲区中
					count=client.read(receivebuffer);
					if(count>0){
						receiveText = new String( receivebuffer.array(),0,count);
						System.out.println("客户端接受服务器端数据--:"+receiveText);
						client.register(selector, SelectionKey.OP_WRITE);
					}

				} else if (selectionKey.isWritable()) {
					sendbuffer.clear();
					client = (SocketChannel) selectionKey.channel();
					sendText = "message from client--" + (flag++);
					sendbuffer.put(sendText.getBytes());
					 //将缓冲区各标志复位,因为向里面put了数据标志被改变要想从中读取数据发向服务器,就要复位
					sendbuffer.flip();
					client.write(sendbuffer);
					System.out.println("客户端向服务器端发送数据--："+sendText);
					client.register(selector, SelectionKey.OP_READ);
				}
			}
			selectionKeys.clear();
		}
	}
}

           个人感觉，JAVA NIO的操作时麻烦了不少，但是无疑这样做效率会得到很大的提升。

评论

2 楼 sahala3293 2012-07-03  

构造方法里面是不是尽量不要抛出异常，会不会导致一些奇怪的问题

1 楼 diecui1202 2012-03-26  

学习了，感谢分享！