//打開選擇器
Selector selector = Selector.open();
//打開通到
ServerSocketChannel socketChannel = ServerSocketChannel.open();
//配置非阻塞模型
socketChannel.configureBlocking(false);
//綁定端口
socketChannel.bind(new InetSocketAddress(8080));
//注冊(cè)事件，OP_ACCEPT只適用于ServerSocketChannel 
socketChannel.register(selector, SelectionKey.OP_ACCEPT);
while (true) {
    selector.select();
    Set<SelectionKey> selectionKeys = selector.selectedKeys();
    Iterator<SelectionKey> iter = selectionKeys.iterator();
    while(iter.hasNext()) {
        SelectionKey key = iter.next();
        if(key.isAcceptable()) {
            SocketChannel channel = ((ServerSocketChannel)key.channel()).accept();
            channel.configureBlocking(false);
            channel.register(selector,SelectionKey.OP_READ);
        }
        
        if(key.isWritable()) {
        }
        
        if(key.isReadable()) {
            SocketChannel channel = (SocketChannel) key.channel();
            ByteBuffer readBuffer = ByteBuffer.allocate(1024);
            channel.read(readBuffer);
            readBuffer.flip();
            // handler Buffer
            // 一般是響應(yīng)客戶端的數(shù)據(jù)
            // 直接是write寫不就完事了嘛，為啥需要write事件？
            // channel.write(...)
        }
        iter.remove();
    }
}

// 200M的Buffer
ByteBuffer buffer = .... 

while(buffer.hasRemaining()) {
    // 該方法只會(huì)寫入小于socket's output buffer空閑區(qū)域的任何字節(jié)數(shù)
    // 并返回寫入的字節(jié)數(shù)，可能是0字節(jié)
    channel.write(buffer);
}

if(key.isReadable()) {
	// 200M Buffer
    ByteBuffer buffer = .... 
    // 注冊(cè)寫事件
    key.interestOps(key.interestOps() | SelectionKey.OP_WRITE);
    // 綁定Buffer
    key.attach(buffer);
}
// 可寫分支
if(key.isWritable()) {
    ByteBuffer buffer = (ByteBuffer) key.attachment();
    SocketChannel channel = (SocketChannel) key.channel();
    if (buffer.hasRemaining()) {
        channel.write(buffer)
    } else {
        // 發(fā)送完了就取消寫事件，否則下次還會(huì)進(jìn)入寫事件分支（因?yàn)橹灰€可寫，就會(huì)進(jìn)入）
        key.interestOps(key.interestOps() & ~SelectionKey.OP_WRITE);
    }
}

// 打開選擇器
Selector selector = Selector.open();
// 打開通道
SocketChannel socketChannel = SocketChannel.open();
// 配置非阻塞模型
socketChannel.configureBlocking(false);
// 連接Server
socketChannel.connect(new InetSocketAddress("127.0.0.1",8080));
// 注冊(cè)事件
socketChannel.register(selector, SelectionKey.OP_CONNECT | SelectionKey.OP_READ);
// 循環(huán)處理
while (true) {
    selector.select();
    Set<SelectionKey> keys = selector.selectedKeys();
    Iterator<SelectionKey> iter = keys.iterator();
    while(iter.hasNext()) {
        SelectionKey key = iter.next();
        if(key.isConnectable()) {
            // 連接建立或者連接建立不成功
            SocketChannel channel = (SocketChannel) key.channel();
            // 完成連接建立
            if(channel.finishConnect()) {
                
            }
        }
        
        if(key.isReadable()) {
            SocketChannel channel = (SocketChannel) key.channel();
            ByteBuffer buffer = ByteBuffer.allocate(500 * 1024 * 1024);
            buffer.clear();
            channel.read(buffer);
            // buffer Handler
        }
        iter.remove();
    }
}