Java NIO 必知必会（Example）

管道流：

Java NIO 管道是2个线程之间的单向数据连接。Pipe有一个source通道和一个sink通道。数据会被写到sink通道，从source通道读取。

 package base.nio.threaddemo;

 import java.io.IOException;

 import java.nio.ByteBuffer;

 import java.nio.channels.Pipe;

 /**

  * @program: Lear-Java

  * @description:

  * @author: Mr.Dai

  * @create: 2018-10-05 20:43

  **/

 public class ThreadSend {

     private Pipe pipe;

     private void init() throws Exception {

         this.pipe = Pipe.open();

     }

     class SendInner1 extends Thread {

         @Override

         public void run() {

             // 单向流 发送数据

             try {

                 Pipe.SinkChannel sink = pipe.sink();

                 sink.configureBlocking(false);

                 while (true) {

                     if (sink.isOpen()) {

                         sink.write(ByteBuffer.wrap("abcd".getBytes()));

                     }

                     Thread.sleep(1000);

                 }

             } catch (InterruptedException | IOException e) {

                 e.printStackTrace();

             }

         }

     }

     class ReverInner extends Thread {

         @Override

         public void run() {

             try {

                 // 单向流 拿到数据

                 Pipe.SourceChannel source = pipe.source();

                 source.configureBlocking(false);

                 while (true) {

                     if (source.isOpen()) {

                         ByteBuffer buffer = ByteBuffer.allocate(10);

                         buffer.clear();

                         source.read(buffer);

                         // 这里必须去掉 trim

                         if(new String(buffer.array()).trim().equals("")){

                             continue;

                         }

                         System.out.println(new String(buffer.array()).trim());

                     }

                     Thread.sleep(1000);

                 }

             } catch (InterruptedException | IOException e) {

                 e.printStackTrace();

             }

         }

     }

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

         ThreadSend send = new ThreadSend();

         send.init();

         SendInner1 sendI = send.new SendInner1();

         ReverInner revI = send.new ReverInner();

         sendI.start();

         revI.start();

     }

 }

套接字通道流

非阻塞模式

ServerSocketChannel可以设置成非阻塞模式。在非阻塞模式下，accept() 方法会立刻返回，如果还没有新进来的连接，返回的将是null。因此，需要检查返回的SocketChannel是否是null。如：

 ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();  

 serverSocketChannel.socket().bind(new InetSocketAddress(9999));

 serverSocketChannel.configureBlocking(false);  

 6   while(true){

     SocketChannel socketChannel =

             serverSocketChannel.accept();  

     if(socketChannel != null){

         //do something with socketChannel...

     }

 }

server：

 package base.nio.chatdemo;

 import java.net.InetSocketAddress;

 import java.nio.ByteBuffer;

 import java.nio.channels.SelectionKey;

 import java.nio.channels.Selector;

 import java.nio.channels.ServerSocketChannel;

 import java.nio.channels.SocketChannel;

 import java.util.Iterator;

 import java.util.Set;

 /**

  * @program: Lear-Java

  * @description: Nio 聊天服务端

  * @author: Mr.Dai

  * @create: 2018-10-05 16:31

  **/

 public class ChatServer {

     /**

      * 通道管理器

      */

     private Selector selector;

     private void initServer(int port) throws Exception{

         ServerSocketChannel serverChannel  = ServerSocketChannel.open();

         serverChannel .socket().bind(new InetSocketAddress(port));

         // 配置非阻塞

         serverChannel .configureBlocking(false);

         this.selector=Selector.open();

         /**

          * 将通道管理器和该通道绑定，并为该通道注册selectionKey.OP_ACCEPT事件

          * 注册该事件后，当事件到达的时候，selector.select()会返回，

          * 如果事件没有到达selector.select()会一直阻塞

          * selector.selectNow() 立即返回 无论是否准备好 可能返回0

          */

         serverChannel .register(this.selector, SelectionKey.OP_ACCEPT);

     }

     /**

      * 采用轮训的方式监听selector上是否有需要处理的事件，如果有，进行处理

      */

     public void listen() throws Exception {

         System.out.println("start------------------->");

         while (true){

             // 在没有注册事件来到时 将会一直阻塞

             selector.select();

             Set<SelectionKey> set = selector.selectedKeys();

             Iterator<SelectionKey> iterator = set.iterator();

             while (iterator.hasNext()){

                 SelectionKey key = iterator.next();

                 // 移除当前阻塞队列

                 iterator.remove();

                 if(key.isAcceptable()){

                     ServerSocketChannel server = (ServerSocketChannel) key.channel();

                     SocketChannel channel = server.accept();

                     channel.configureBlocking(false);

                     // 服务端发送数据

                     channel.write(ByteBuffer.wrap(new String("hello client").getBytes()));

                     // 在客户端连接成功之后，为了可以接收到客户端的信息，需要给通道设置读的权限

                     channel.register(this.selector,SelectionKey.OP_READ);

                 }else if(key.isReadable()){

                     SocketChannel channel  = (SocketChannel) key.channel();

                     ByteBuffer buffer = ByteBuffer.allocate(10);

                     channel.read(buffer);

                     String msg = new String(buffer.array()).trim();

                     System.out.println("客户端发送过来的讯息："+msg);

                     // 在读取后 将柱塞队列数据 改变监听为Accept

                     ByteBuffer outBuffer = ByteBuffer.wrap(msg.getBytes());

                     channel.write(outBuffer);

                 }

                           }

         }

     }

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

         ChatServer server = new ChatServer();

         server.initServer(8989);

         server.listen();

     }

 }

clien：

 package base.nio.chatdemo;

 import java.io.IOException;

 import java.net.InetSocketAddress;

 import java.nio.ByteBuffer;

 import java.nio.channels.SelectionKey;

 import java.nio.channels.Selector;

 import java.nio.channels.SocketChannel;

 import java.util.Iterator;

 /**

  * @program: Lear-Java

  * @description: nio 聊天客户端

  * @author: Mr.Dai

  * @create: 2018-10-05 16:31

  **/

 public class ChatClient {

     /**

      *  提供柱阻塞队列 管理器

      */

     private Selector selector;

     private void ininCliect(String ip,int port) throws Exception{

         SocketChannel channel  = SocketChannel.open();

         channel .connect(new InetSocketAddress(ip,port));

         this.selector=Selector.open();

         channel .configureBlocking(false);

         channel .register(this.selector, SelectionKey.OP_CONNECT);

     }

     public void listen() throws Exception {

         while (true){

             selector.select();

             Iterator<SelectionKey> ite  = selector.selectedKeys().iterator();

             while (ite.hasNext()){

                 SelectionKey key = ite .next();

                 ite .remove();

                 if(key.isConnectable()){

                     SocketChannel channel = (SocketChannel) key.channel();

                     // 是否准备好连接

                     if(channel.isConnectionPending()){

                         channel.finishConnect();

                     }

                     channel.configureBlocking(false);

                     // 向server 发送数据

                     channel.write(ByteBuffer.wrap("向server 发送数据".getBytes()));

                     channel.register(selector,SelectionKey.OP_READ);

                 }else if(key.isReadable()){

                         m1(key);

                 }

             }

         }

     }

     private void m1(SelectionKey key) throws IOException {

         SocketChannel channel = (SocketChannel) key.channel();

         ByteBuffer buffer = ByteBuffer.allocate(10);

         channel.read(buffer);

         System.out.println("服务端的消息为:"+new String(buffer.array()));

         ByteBuffer outBuffer = ByteBuffer.wrap(new String("aaa").getBytes());

         channel.write(outBuffer);

     }

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

         ChatClient client = new ChatClient();

         client.ininCliect("127.0.0.1",8989);

         client.listen();

     }

 }

巴特西

Java NIO 必知必会（Example）

管道流：

套接字通道流

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