package nioDemo;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.charset.Charset;
public class ServiceDatagramChannelDemo {
public static class UDPEchoService implements Runnable{
private int port;
public UDPEchoService(int port){
this.port = port;
}
@Override
public void run(){
ByteBuffer readBuffer = ByteBuffer.allocate(256);
ByteBuffer writeBuffer = ByteBuffer.allocate(256);
DatagramChannel dc = null;
try{
/*服务器端使用默认的阻塞IO的方式*/
dc = DatagramChannel.open();
dc.bind(new InetSocketAddress(port));
System.out.println("service start");
while(!Thread.currentThread().isInterrupted()){
try{
/*先读取客户端发送的消息，直到读取到消息才会返回*/
/*只能调用receive方法，因为不知道哪个地址给服务器发信息，没法实现调用connect方法*/
/*dc是阻塞的，所以receive方法要等到接收到数据才返回*/
SocketAddress clientAddress = dc.receive(readBuffer);
readBuffer.flip();
CharBuffer charBuffer = Charset.defaultCharset().decode(readBuffer);
System.out.println(charBuffer.array());
/*调用send方法向客户端发送的消息，
*dc是阻塞的,所以直到send方法把数据全部写入到socket缓冲区才返回*/
writeBuffer.put("echo : ".getBytes());
readBuffer.rewind();
writeBuffer.put(readBuffer);
writeBuffer.flip();
dc.send(writeBuffer, clientAddress);
readBuffer.clear();
writeBuffer.clear();
}catch(IOException e){
System.out.println("receive from or send to client failed");
}
}
}catch(IOException e){
System.out.println("server error");
}finally{
try {
if(dc != null){
dc.close();
}
} catch (IOException e) {
}
}
}
}
public static void main(String[] args) throws IOException{
new Thread(new UDPEchoService(8080)).start();
}
}
2）客户端代码