nio udp server client Demo例子（五）

udp有些东西还是很懵逼，只是写了个小小的接受和发送数据的小Demo，这个小Demo并没有体现nio应有的优势（单个线程连接多个客户端）

服务端：

package Demo5;import java.io.IOException;import java.net.InetSocketAddress;import java.nio.ByteBuffer;import java.nio.channels.DatagramChannel;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.util.Iterator;public class NioUdpServer {//http://blog.csdn.net/foart/article/details/47608475//http://www.cnblogs.com/rainy-shurun/p/5756501.html//这个要多琢磨琢磨private int port = 8000;  private DatagramChannel channel;  private Selector selector = null;  public void initNioUdpServer() throws IOException{//创建udp连接通道channel = DatagramChannel.open();//创建通道管理器selector = Selector.open();//设置通道为非阻塞性通道（不会创建线程）channel.configureBlocking(false);//将该通道绑定对应的端口channel.socket().bind(new InetSocketAddress(port));//为通道注册通道管理器，并且注册一个可读就绪事件channel.register(selector, SelectionKey.OP_READ);}//启动轮询来接受来自客户端的数据报文public void listen() throws IOException {System.out.println("new nio server start");while(true){//有通道就绪时（即select()的返回值大于0时），不阻塞，否则，阻塞，不会有任何的通道加入selector.select();System.out.println("new udp server channel join");Iterator<?> it = this.selector.selectedKeys().iterator();while(it.hasNext()){SelectionKey key = (SelectionKey) it.next();it.remove();//此处负责把udp连接断掉clientHandler(key);//处理来自客户端的连接（通道的各种状态）}}}private void clientHandler(SelectionKey key) throws IOException {if(key.isReadable()){handlerRead(key);}}//udp的接受客户端数据和响应的过程private void handlerRead(SelectionKey key) throws IOException {//接受数据过程DatagramChannel channel =  (DatagramChannel) key.channel();ByteBuffer buf = ByteBuffer.allocate(1024);buf.clear();//固定写法InetSocketAddress address =(InetSocketAddress)channel.receive(buf);//接受来自客户端通道的数据buf.flip();//固定写法String content = "";while(buf.hasRemaining()){buf.get(new byte[buf.limit()]);content += new String(buf.array());}System.out.println("udp server content："+content);buf.clear();//发送数据过程ByteBuffer buf2 = ByteBuffer.allocate(65500);buf2.clear();buf2.put("udp server put data process!!".getBytes());buf2.flip();this.channel.send(buf2,address);}public void close() throws IOException{this.channel.close();this.selector.close();}public static void main(String[] args) throws IOException {NioUdpServer server = new NioUdpServer();server.initNioUdpServer();server.listen();//server.close();}}

客户端：

package Demo5;import java.io.IOException;import java.net.InetSocketAddress;import java.nio.ByteBuffer;import java.nio.channels.DatagramChannel;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.util.Iterator;public class NioUdpClient {private DatagramChannel channel;private String ip = "127.0.0.1";private int port = 8000;private Selector selector;public void initUdpClient() throws IOException{channel = DatagramChannel.open();selector = Selector.open();channel.configureBlocking(false);channel.connect(new InetSocketAddress(ip, port));//有个现象：//两个控制台君出现不接受数据也不发送数据，仅仅启动了两端// new nio client start // new nio server start//原因猜测：注册任意事件都是与通道相关的，但是，很明显当客户端启动时，通道的各种就绪状态还没出现，所以需要手动//channel.write(ByteBuffer.wrap("client send msg".getBytes()));//来引发服务器端通道相关的就绪状态channel.write(ByteBuffer.wrap("client send msg".getBytes()));channel.register(selector, SelectionKey.OP_READ);}public void listen() throws IOException{System.out.println("new nio client start");while(true){selector.select();System.out.println("new udp client channel join");Iterator<?> it = this.selector.selectedKeys().iterator();while(it.hasNext()){SelectionKey key =  (SelectionKey) it.next();it.remove();handler(key);}}}public void handler(SelectionKey key) throws IOException{if(key.isReadable()){handlerRead( key);}}public void handlerRead(SelectionKey key) throws IOException{DatagramChannel channel =  (DatagramChannel) key.channel();//接受来自服务端的数据报文ByteBuffer buf = ByteBuffer.allocate(65500);buf.clear();channel.receive(buf); buf.flip();String content = "";while(buf.hasRemaining()){buf.get(new byte[buf.limit()]);content += new String(buf.array());}buf.clear();System.out.println("udp client content :" + content);}public void close() throws IOException{this.channel.close();this.selector.close();}public static void main(String[] args) throws IOException {NioUdpClient client = new NioUdpClient();client.initUdpClient();client.listen();//client.close();}}

测试：

eclipse下

1、启动server：

2、启动一个Client：

3、启动另外一个Client:

4、查看服务端的结果（打印了两遍msg，测试准确）：