詳解Java非阻塞I/O模型之NIO技術(shù)相關(guān)知識(shí)內(nèi)容

//初始化一個(gè)網(wǎng)絡(luò)地址，并綁定7000端口號(hào)
InetSocketAddress inetSocketAddress = new InetSocketAddress(7000);
//ServerSocketChannel.open() 方法實(shí)例化一個(gè)ServerSocketChannel對(duì)象
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
//serverSocketChannel綁定初始化的網(wǎng)絡(luò)地址，并開(kāi)始監(jiān)聽(tīng)
serverSocketChannel.socket().bind(inetSocketAddress);
//將這個(gè)通道設(shè)置為非阻塞的
serverSocketChannel.configureBlocking(false);

//得到一個(gè)Selector對(duì)象
Selector selector = Selector.open();
//在channel上注冊(cè)selector，并且告訴這個(gè)選擇器初始應(yīng)該監(jiān)聽(tīng)的事件，
//SelectionKey.OP_ACCEPT 為監(jiān)聽(tīng)鏈接進(jìn)入的事件，初始化并不監(jiān)聽(tīng)數(shù)據(jù)讀取的事件
//SelectionKey.OP_READ 事件讀取事件，需要在有鏈接進(jìn)入時(shí)，配合鏈接一起注冊(cè)
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);

//循環(huán)等待客戶端鏈接
while(true){
     //等待1秒，1秒內(nèi)沒(méi)有鏈接事件發(fā)生，直接返回
     if(selector.select(1000)==0){
         System.out.println("服務(wù)器等待了1秒，無(wú)連接進(jìn)入");
         continue;
      }
      //有事件發(fā)生，拿到集合
      //selector.selectedKeys() 關(guān)注事件的集合
      //通過(guò)這個(gè)可以反向獲取通道
      Set<SelectionKey> selectionKeys = selector.selectedKeys();

      //遍歷集合，使用迭代器
      Iterator<SelectionKey> keyIterator = selectionKeys.iterator();
      while(keyIterator.hasNext()){
           //獲取事件key
           SelectionKey key = keyIterator.next();
           //根據(jù)key對(duì)應(yīng)的通道發(fā)生的事件做相應(yīng)的處理
           if(key.isAcceptable()){
               //如果是ACCEPT事件，客戶端鏈接
               //傳統(tǒng)的accept()是阻塞的，但是在NIO中，當(dāng)key.isAcceptable()方法返回true的時(shí)候，這個(gè)鏈接就已經(jīng)存在了，所以accept()會(huì)立刻執(zhí)行
               SocketChannel socketChannel = serverSocketChannel.accept();
               socketChannel.configureBlocking(false);
               //將當(dāng)前的socketChannel注冊(cè)的selector,關(guān)注事件為READ，同時(shí)給Channel關(guān)聯(lián)一個(gè)Buffer
               SelectionKey register = socketChannel.register(selector, SelectionKey.OP_READ, ByteBuffer.allocate(128));

           }else if(key.isReadable()){
               //發(fā)生了READ事件
               //通過(guò)key反向獲取Channel
               SocketChannel channel = (SocketChannel)key.channel();
               //獲取到該channel關(guān)聯(lián)的buffer
               ByteBuffer buffer =(ByteBuffer) key.attachment();
               channel.read(buffer);
               System.out.println("From 客戶端 ："+new String(buffer.array()));

           }

           //手動(dòng)在集合中移除當(dāng)前的SelectionKey否則可能會(huì)出現(xiàn)重復(fù)操作
           keyIterator.remove();

       }


}