Java TCP異步數據接收

以前一直採用.Net編寫服務端程序，最近須要切換到Linux平臺下，因而嘗試採用Java編寫數據服務器。TCP異步鏈接在C#中很容易實現，網上也有不少可供參考的代碼。但Java異步TCP的參考資料較少，網上例程可能是阻塞多線程方法，因爲線程的開銷較大，當客戶端較多時系統資源的消耗也較大。

綜合網上和書本的相關知識，本文給出一個Java TCP異步接收數據的代碼示例，並給出相關的註釋。

/**
 * TcpAsyncServer.java
 */

import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.net.*;
import java.util.Iterator;

public class TcpAsyncServer {

    /*監聽端口*/
    int port = 6000;
    /*緩衝區大小*/
    ByteBuffer buffer = ByteBuffer.allocate(1024);
    /*其它相關定義*/
    Selector selector;
    ServerSocketChannel channel;
    ServerSocket socket;

    /*啓動*/
    public void Start() throws Exception {
        /*初始化一個Selector*/
        selector = Selector.open();
        /*打開通道*/
        channel = ServerSocketChannel.open();
        /*非阻塞模式*/
        channel.configureBlocking(false);
        /*本機IP*/
        //InetAddress ip = InetAddress.getByName("127.0.0.1");
        InetAddress ip = InetAddress.getLocalHost();
        System.out.println(ip.toString());
        /*綁定IP和端口*/
        InetSocketAddress address = new InetSocketAddress(ip,port);
        socket = channel.socket();
        socket.bind(address);
        /*啓動監聽*/
        System.out.println("TCP服務器開始監聽...");
        Listen();
    }

    /*中止*/
    public void Stop() throws Exception {
        channel.close();
        selector.close();
    }

    /*監聽*/
    public void Listen() throws Exception {
        /*註冊接收事件*/
        channel.register(selector,SelectionKey.OP_ACCEPT);
        /*無限循環*/
        while (true) {
            selector.select();
            /*輪詢事件*/
            Iterator iter = selector.selectedKeys().iterator();
            while (iter.hasNext()) {
                SelectionKey key =  (SelectionKey)iter.next();
                iter.remove();
                /*事件分類處理*/
                if (key.isAcceptable()) {
                    ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
                    SocketChannel sc = ssc.accept();
                    sc.configureBlocking(false);
                    sc.register(selector, SelectionKey.OP_READ);
                    System.out.println("新終端已鏈接:"+ sc.getRemoteAddress());
                }
                else if (key.isReadable()) {
                    SocketChannel sc = (SocketChannel)key.channel();
                    int recvCount = sc.read(buffer);
                    if (recvCount > 0) {
                        byte[] arr = buffer.array();
                        System.out.println(sc.getRemoteAddress() + "發來數據: "+ new String(arr));
                        buffer.flip();
                    }
                    else {
                        sc.close();
                    }
                    buffer.clear();
                }

                else {

                }


            }

        }

    }

}

/**
 * server.java
 */

public class server {

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

        TcpAsyncServer tcpServer = new TcpAsyncServer();
        tcpServer.Start();

    }
}

 

效果演示：

1. 利用TCP工具發送數據

3. 接收數據