javaudp实现

⑴ 请教大神，怎么使用java实现UDP端口扫描

给你个UDP服务端与客户端的示例:

服务端代码:

importjava.net.DatagramPacket;
importjava.net.InetAddress;
importjava.net.MulticastSocket;

publicclassUDPMulticastServer{
	finalstaticintRECEIVE_LENGTH=1024;

	staticStringmulticastHost="224.0.0.1";

	staticintlocalPort=9998;

	publicstaticvoidmain(String[]args)throwsException{

		InetAddressreceiveAddress=InetAddress.getByName(multicastHost);

		if(!receiveAddress.isMulticastAddress()){//测试是否为多播地址

			thrownewException("请使用多播地址");

		}

		intport=localPort;

		=newMulticastSocket(port);

		receiveMulticast.joinGroup(receiveAddress);

		
		booleanisStop=false;
		while(!isStop){
			DatagramPacketdp=newDatagramPacket(newbyte[RECEIVE_LENGTH],RECEIVE_LENGTH);
			receiveMulticast.receive(dp);
			Stringdata=newString(dp.getData()).trim();
			System.out.println(data);
			if("exit".equals(data)){
				System.out.println("程序退出");
				isStop=true;
			}
		}

		receiveMulticast.close();
	}
}

客户端代码:

importjava.net.DatagramPacket;
importjava.net.InetAddress;
importjava.net.MulticastSocket;

publicclassUDPMulticastClient{
	staticStringdestAddressStr="224.0.0.1";
	
staticintdestPortInt=9998;

staticintTTLTime=4;

publicstaticvoidmain(String[]args)throwsException{	InetAddressdestAddress=InetAddress.getByName(destAddressStr);

	if(!destAddress.isMulticastAddress()){//检测该地址是否是多播地址
	
	thrownewException("地址不是多播地址");
	
	}

	intdestPort=destPortInt;
	
	
	MulticastSocketmultiSocket=newMulticastSocket();
	
//	intTTL=TTLTime;
//	multiSocket.setTimeToLive(TTL);
	
	byte[]sendMSG="exit".getBytes();
	
	DatagramPacketdp=newDatagramPacket(sendMSG,sendMSG.length,destAddress,destPort);
	
	multiSocket.send(dp);
	
	multiSocket.close();
	
	}

}

⑵ java怎么实现JSON打包UDP

java实现JSON打包UDP cJSON支持在C程序中创建和解析JSON数据，其提供多种方法供C程序使用，最直接的是将cJSON.c和cJSON.h加入到C工程中

（1） QJsonObject用于在Qt中创建JSON对象

（2）数据传输通过UDP运行