udp 傳輸，可解決中文不能正確傳輸，亂碼問題

剛開始，按JDK 裡的例子寫，

 // join a Multicast group and send the group salutations ... String msg = "Hello"; InetAddress group = InetAddress.getByName("228.5.6.7"); MulticastSocket s = new MulticastSocket(6789); s.joinGroup(group); DatagramPacket hi = new DatagramPacket(msg.getBytes(), msg.length(),                             group, 6789); s.send(hi); // get their responses!byte[] buf = new byte[1000]; DatagramPacket recv = new DatagramPacket(buf, buf.length); s.receive(recv); ... // OK, I'm done talking - leave the group... s.leaveGroup(group);

這樣寫傳英文，可以，但是傳中文， 就不能正確傳輸。

看了網上的一些說法，其中有說到用流的方法，所以，試一下，可以解決了。

完整代碼如下：

public class MudpSrv {int port = 6789;public void sendMessage(String msg,MulticastSocket socket) throws IOException{ByteArrayOutputStream ostream = new ByteArrayOutputStream();DataOutputStream dataStream = new DataOutputStream(ostream);dataStream.writeUTF(msg);dataStream.close();byte[] data = ostream.toByteArray();InetAddress address = InetAddress.getByName("230.3.3.3");socket.joinGroup(address);DatagramPacket dp = new DatagramPacket(data, data.length, address,port);socket.send(dp);}public void getMessage(MulticastSocket socket) throws IOException{byte[] bs = new byte[1000];DatagramPacket packet = new DatagramPacket(bs, bs.length);socket.receive(packet);DataInputStream istream = new DataInputStream(new ByteArrayInputStream(packet.getData(), packet.getOffset(), packet.getLength()));String msg = istream.readUTF();System.out.println(msg);}public static void main(String args[]) throws IOException{MudpSrv srv = new MudpSrv();MulticastSocket socket = new MulticastSocket(srv.port);srv.sendMessage("螢火蟲，皎白月光，遊過四季",socket);srv.getMessage(socket);}}