java NIO套接字编程

在java的套接字编程中，大部分一般使用阻塞IO套接字编程。套接字的读取和写入会阻塞(也就是说不管现在有没有写入/读出数据 调用read和write方法将会阻塞)。而NIO将I/O事件注册，当特定的注册I/O事件到达时会通知您。不需要轮询，也不需要创建大量的线程下面一个例子：下载

Server代码  

package simple.socket;  
  
import java.io.IOException;  
import java.net.InetSocketAddress;  
import java.net.ServerSocket;  
import java.nio.ByteBuffer;  
import java.nio.channels.*;  
import java.util.Iterator;  
import java.util.Set;  
  
/**  
 * Created by banxia on 16/10/12.  
 */  
public class UseNioSocket {  
  
  
    public static void main(String[] args) throws IOException {  
  
        // 创建一个selector 对象  
        Selector selector = Selector.open();  
  
        ServerSocketChannel ssc = ServerSocketChannel.open();  
        ssc.configureBlocking(false);  
        ssc.socket().bind(new InetSocketAddress(8888));  
        ssc.register(selector, SelectionKey.OP_ACCEPT);  
        ByteBuffer buffer = ByteBuffer.allocate(1024);  
  
        System.out.println("服务已经启动端口:" + 8888);  
  
        while (true) {  
  
            int selectNum = selector.select();  
            System.out.println("selectNum=" + selectNum);  
  
            if (selectNum <= 0) {  
                continue;  
            }  
            // 获取  
  
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();  
  
            while (it.hasNext()) {  
  
                SelectionKey key = it.next();  
  
                if (key.readyOps() == SelectionKey.OP_ACCEPT) {  
                    // 接收 accept  
  
                    ServerSocketChannel channel = (ServerSocketChannel) key.channel();  
                    SocketChannel accept = channel.accept();  
                    accept.configureBlocking(false);  
                    System.out.println("接收客户端:" + accept.socket().getInetAddress().getHostAddress() + ":" +  accept.socket().getPort());  
                    accept.register(selector, SelectionKey.OP_READ);  
                    it.remove();  
  
  
                } else {  
  
                    SocketChannel sc = (SocketChannel) key.channel();  
                    System.out.println("接收客户端:" + sc.socket().getInetAddress().getHostAddress() + ":" + sc.socket().getPort() +"开始处理...");  
                    while (true) {  
                        buffer.clear();  
                        long l = sc.read(buffer);  
                        if (l <= 0) {  
                            break;  
                        }  
                        System.out.print(".");  
                        buffer.flip();  
                        sc.write(buffer);  
  
  
                    }  
                    System.out.print("\n");  
                    it.remove();  
                    System.out.println("接收客户端:" + sc.socket().getInetAddress().getHostAddress() + ":" + sc.socket().getPort() +"处理完成处理...");  
  
                }  
  
            }  
  
  
        }  
  
  
    }  
}