NIO学习笔记(4)-简单echo实例

echo小例子 

服务端

1. import java.io.IOException; 
2. import java.net.InetSocketAddress; 
3. import java.net.ServerSocket; 
4. import java.nio.ByteBuffer; 
5. import java.nio.channels.SelectionKey; 
6. import java.nio.channels.Selector; 
7. import java.nio.channels.ServerSocketChannel; 
8. import java.nio.channels.SocketChannel; 
9. import java.util.Iterator; 
10.  
11.  
12. public class Ex2Server { 
13.  
14.     /** 
15.      * @param args 
16.      * @throws IOException  
17.      */ 
18.     public static void main(String[] args) throws IOException { 
19.         //第一件事是创建一个 Selector 
20.         Selector selector = Selector.open(); 
21.          
22.         //要监听的每一个端口都需要有一个 ServerSocketChannel  
23.         ServerSocketChannel serverSocketChannel = ServerSocketChannel.open(); 
24.         serverSocketChannel.configureBlocking(false); 
25.  
26.         ServerSocket serverSocket = serverSocketChannel.socket(); 
27.         serverSocket.bind(new InetSocketAddress(12345));//绑定一个端口 
28.          
29.         //SelectionKey 代表这个通道在此 Selector 上的这个注册。 
30.         //当某个 Selector 通知您某个传入事件时，它是通过提供对应于该事件的 SelectionKey 来进行的。 
31.         //SelectionKey 还可以用于取消通道的注册。 
32.         SelectionKey selectionKey = serverSocketChannel.register( 
33.                 selector, SelectionKey.OP_ACCEPT);//注册accept事件 
34.          
35.         int num = 0; 
36.         ByteBuffer buffer = ByteBuffer.allocate(1024); 
37.         while(true){ 
38.             //select方法会阻塞，直到至少有一个已注册的事件发生 
39.             num = selector.select(); 
40.              
41.             Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); 
42.             SelectionKey key = null; 
43.             while(iterator.hasNext()){ 
44.                  key = iterator.next(); 
45.                  if(key.isAcceptable()){//accept 
46.                      ServerSocketChannel channel = (ServerSocketChannel)key.channel(); 
47.                      //相当于从ServerSocket中accept一个socket 
48.                      SocketChannel socketChannel = channel.accept(); 
49.                      socketChannel.configureBlocking(false);//设为非阻塞 
50.                      socketChannel.register(selector, SelectionKey.OP_READ); 
51.                       
52.                  }else if(key.isReadable()){ 
53.                      SocketChannel channel = (SocketChannel)key.channel(); 
54.                      int readNum = 0; 
55.                      while(readNum != -1){ 
56.                          buffer.clear(); 
57.                          channel.read(buffer);//读出 
58.                           
59.                          buffer.flip(); 
60.                          channel.write(buffer); 
61.                      } 
62.                      //channel.close(); 
63.                       
64.                  }else if(key.isWritable()){ 
65.                       
66.                  } 
67.                  iterator.remove(); 
68.             } 
69.         } 
70.          
71.     } 
72.  
73. } 

客户端

1. import java.io.BufferedReader; 
2. import java.io.IOException; 
3. import java.io.InputStreamReader; 
4. import java.io.OutputStreamWriter; 
5. import java.io.PrintWriter; 
6. import java.net.InetSocketAddress; 
7. import java.net.Socket; 
8. import java.net.SocketAddress; 
9.  
10.  
11. public class Ex2Client { 
12.  
13.     /** 
14.      * @param args 
15.      * @throws IOException  
16.      */ 
17.     public static void main(String[] args) throws IOException { 
18.         SocketAddress address = new InetSocketAddress("localhost", 12345); 
19.         Socket s = new Socket(); 
20.         s.connect(address); 
21.         PrintWriter writer = new PrintWriter( new OutputStreamWriter(s.getOutputStream())); 
22.         writer.println("abc"); 
23.         writer.flush(); 
24.          
25.         BufferedReader reader = new BufferedReader(new InputStreamReader(s.getInputStream())); 
26.         System.out.println(reader.readLine()); 
27.          
28.         writer.close(); 
29.         reader.close(); 
30.         s.close(); 
31.     } 
32.  
33. } 

   如果写入的内容比较多，可以把读跟写分开

1. import java.io.IOException; 
2. import java.net.InetSocketAddress; 
3. import java.net.ServerSocket; 
4. import java.nio.ByteBuffer; 
5. import java.nio.channels.SelectionKey; 
6. import java.nio.channels.Selector; 
7. import java.nio.channels.ServerSocketChannel; 
8. import java.nio.channels.SocketChannel; 
9. import java.util.Iterator; 
10.  
11.  
12. public class Ex2Server2 { 
13.  
14.     /** 
15.      * @param args 
16.      * @throws IOException  
17.      */ 
18.     public static void main(String[] args) throws IOException { 
19.         //第一件事是创建一个 Selector 
20.         Selector selector = Selector.open(); 
21.          
22.         //要监听的每一个端口都需要有一个 ServerSocketChannel  
23.         ServerSocketChannel serverSocketChannel = ServerSocketChannel.open(); 
24.         serverSocketChannel.configureBlocking(false); 
25.  
26.         ServerSocket serverSocket = serverSocketChannel.socket(); 
27.         serverSocket.bind(new InetSocketAddress(12345));//绑定一个端口 
28.          
29.         //SelectionKey 代表这个通道在此 Selector 上的这个注册。 
30.         //当某个 Selector 通知您某个传入事件时，它是通过提供对应于该事件的 SelectionKey 来进行的。 
31.         //SelectionKey 还可以用于取消通道的注册。 
32.         SelectionKey selectionKey = serverSocketChannel.register( 
33.                 selector, SelectionKey.OP_ACCEPT);//注册accept事件 
34.          
35.         int num = 0; 
36.         ByteBuffer buffer = ByteBuffer.allocate(1024); 
37.         while(true){ 
38.             //select方法会阻塞，直到至少有一个已注册的事件发生 
39.             num = selector.select(); 
40.              
41.             Iterator<SelectionKey> iterator = selector.selectedKeys().iterator(); 
42.             SelectionKey key = null; 
43.             while(iterator.hasNext()){ 
44.                  key = iterator.next(); 
45.                  if(key.isAcceptable()){//accept 
46.                      ServerSocketChannel channel = (ServerSocketChannel)key.channel(); 
47.                      //相当于从ServerSocket中accept一个socket 
48.                      SocketChannel socketChannel = channel.accept(); 
49.                      socketChannel.configureBlocking(false);//设为非阻塞 
50.                      socketChannel.register(selector, SelectionKey.OP_READ); 
51.                       
52.                  }else if(key.isReadable()){ 
53.                      SocketChannel channel = (SocketChannel)key.channel(); 
54.                      int readNum = 1; 
55.                      while(readNum > 0){ 
56.                          buffer.clear(); 
57.                          readNum = channel.read(buffer);//读出 
58.                           
59.                          buffer.flip(); 
60.                          //channel.write(buffer); 
61.                      } 
62.                      channel.register(selector, SelectionKey.OP_WRITE); 
63.                      //channel.close(); 
64.                       
65.                  }else if(key.isWritable()){ 
66.                      SocketChannel channel = (SocketChannel)key.channel(); 
67.                      buffer.clear(); 
68.                      buffer.put("测试\r\n".getBytes()); 
69.                      buffer.flip(); 
70.                      channel.write(buffer);
71.  
72.                     //取消写入key的注册，不然一直可写 
73.                      key.cancel(); 
74. //改正：key.cancel会把channel也关闭，这里设置OPS为读，也就把写给反注册掉了
75. key.interestOps(SelectionKey.OP_READ);
76.                  } 
77.                  iterator.remove(); 
78.             } 
79.         } 
80.  
81.     } 
82.  
83. } 

本文转自 dogegg250 51CTO博客，原文链接：http://blog.51cto.com/jianshusoft/692761，如需转载请自行联系原作者