java NIO套接字编程

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：

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...");

                }

            }


        }


    }
}