Netty進階基礎篇之NIO 阻塞通訊（5）

NIO 完成網絡通訊的三個核心：Channel、Buffer、Selector

一、通道（Channel）

負責鏈接

SocketChannel、ServerSocketChannel、DatagramChannel、Pipe.SinkChannel、Pipe.SourceChannel

二、緩衝區（Buffer）

負責數據的存取

三、 選擇器（Selector）

是 SelectableChannel 的多路複用器。用於監控 SelectableChannel 的 IO 情況

四、阻塞網絡通訊copy數據

//客戶端
@Test
public void client() throws IOException{
   //1. 獲取通道
   SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8085));
   
   FileChannel inChannel = FileChannel.open(Paths.get("/Users/tentsuuhou/Desktop/777.txt"), StandardOpenOption.READ);
   
   //2. 分配指定大小的緩衝區
   ByteBuffer buf = ByteBuffer.allocate(1024);
   
   //3. 讀取本地文件，併發送到服務端
   while(inChannel.read(buf) != -1){
      buf.flip();
      sChannel.write(buf);
      buf.clear();
   }
   
   //4. 關閉通道
   inChannel.close();
   sChannel.close();
}

//服務端
@Test
public void server() throws IOException{
   //1. 獲取通道
   ServerSocketChannel ssChannel = ServerSocketChannel.open();
   
   FileChannel outChannel = FileChannel.open(Paths.get("/Users/tentsuuhou/Desktop/666.txt"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
   
   //2. 綁定鏈接
   ssChannel.bind(new InetSocketAddress(8085));
   
   //3. 獲取客戶端鏈接的通道
   SocketChannel sChannel = ssChannel.accept();
   
   //4. 分配指定大小的緩衝區
   ByteBuffer buf = ByteBuffer.allocate(1024);
   
   //5. 接收客戶端的數據，並保存到本地
   while(sChannel.read(buf) != -1){
      buf.flip();
      outChannel.write(buf);
      buf.clear();
   }
   
   //6. 關閉通道
   sChannel.close();
   outChannel.close();
   ssChannel.close();
}

先開啓server端，在開啓client端，這樣就ok了

五、阻塞簡單版client發送server數據

//客戶端
@Test
public void client() throws IOException{
   SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 8080));

   ByteBuffer buf = ByteBuffer.allocate(1024);

   sChannel.shutdownOutput();
   
   //接收服務端的反饋
   int len = 0;
   while((len = sChannel.read(buf)) != -1){
      buf.flip();
      System.out.println(new String(buf.array(), 0, len));
      buf.clear();
   }
   
   sChannel.close();
}

//服務端
@Test
public void server() throws IOException{
   ServerSocketChannel ssChannel = ServerSocketChannel.open();

   ssChannel.bind(new InetSocketAddress(8080));
   
   SocketChannel sChannel = ssChannel.accept();
   
   ByteBuffer buf = ByteBuffer.allocate(1024);

   
   //發送反饋給客戶端
   buf.put("服務端接收數據成功".getBytes());
   buf.flip();
   sChannel.write(buf);
   
   sChannel.close();
   ssChannel.close();
}

client中，sChannel.shutdownOutput(); 若是沒有這個，處於阻塞狀態，server不知道，只有shutdownOutput()才能提醒server端，這樣就能把client的數據傳到server中。