Android UDP通信很簡單的，調用下面這個方法就可以實現客戶端和服務端的UDP通信，

只需要把要發給服務器的數據轉成一個byte數組格式傳進去就行了。

/**客戶端向服務器端發送UDP數據*/
public static void sendUdpData(final byte[] bytesToSend) {
    new Thread(){
        @Override
        public void run() {
            try{
                //IP是服務器地址
                InetAddress serverAddress = InetAddress.getByName(IP
 
);
               
                //PORT是服務器端口號
                int serverPort = PORT;

                DatagramSocket socket = new DatagramSocket();
                socket.setSoTimeout(8000);
                
                //sendPacket發送的數據包
                DatagramPacket sendPacket = new DatagramPacket(bytesToSend,bytesToSend.length,serverAddress,serverPort);
                //receivePacket返回的數據包
                DatagramPacket receivePacket = new DatagramPacket(new byte[bytesToSend.length],bytesToSend.length);

                int tries = 0;
                boolean receivedResponse = false;
                do{
                    socket.send(sendPacket);
                    try{
                        socket.receive(receivePacket);
                        if(!receivePacket.getAddress().equals(serverAddress)){
                            throw new IOException("接收到未知來源的包");
                        }
                        receivedResponse = true;
                    }catch(InterruptedIOException e){
                        tries +=1;
                        Log.i("TAG","Received:"+"Time out,"+(5-tries));
                    }
                }while((!receivedResponse)&&(tries > 5));

                if(receivedResponse){
                    //在這裏可以拿到服務器返回的數據
                    String receiveData=new String(receivePacket.getData());
                    Log.i("TAG","返回數據:"+receiveData);
                }else{
                    Log.i("TAG","NO response -- giving up");
                }
                socket.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }.start();
}

android UDP通信