nio~DatagramChannel

*DatagramChannel是nio中处理UDP的类,可以使用2种方式:

---DatagramChannel.receive(ByteBuffer dst)和DatagramChannel.send(ByteBuffer src, SocketAddress target)

---调用connect()之后,使用read和write.

*方式一,send和receive示例

/**
 * Feb 27, 2011 by dzh
 */
package nio.channel;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;

/**
 * @author dzh
 *
 */
public class DatagramChannelSender {
	
	public static void main(String[] args) {
		try {
			send();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	private static void send() throws IOException{
		DatagramChannel channel =DatagramChannel.open();
		ByteBuffer buffer =ByteBuffer.wrap("下雨的夜晚很安静".getBytes("utf-8"));
		channel.send(buffer, new InetSocketAddress("localhost",10022));
		
		channel.close();
	}
	
}

/**
 * Feb 27, 2011 by dzh
 */
package nio.channel;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.charset.Charset;

/**
 * @author dzh
 *
 */
public class DatagramChannelReveiver {
	
	public static void main(String[] args) {
		try {
			receive();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	private static void receive() throws IOException{
		DatagramChannel channel =DatagramChannel.open();
		channel.socket().bind(new InetSocketAddress(10022));
		
		ByteBuffer buffer =ByteBuffer.allocate(60);
		while(channel.receive(buffer)==null){ 
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		
		buffer.flip();
		String recStr =Charset.forName("utf-8").newDecoder().decode(buffer).toString();
		System.out.println(recStr);
		
		channel.close();
		
	}
	
}

*方式2

---connect()说明

1.只起到,限制数据包的接收和发送来源

2.不会阻塞

3.使用read和write的必要条件,否则抛出"NotYetConnectedException "

*其他注意

---DatagramChannel不能注册SelectionKey.OP_CONNECT

---数据包的最大容量是65507字节