我正在尝试使用 UDP 套接字在 Java 中创建一个非常简单的聊天应用程序。有一台服务器和多个客户端。
现在我的代码是：
服务器 ：
package chat;
import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Set;
class User{
InetAddress addr;
int port;
User(InetAddress a,int p){
addr = a;
port = p;
}
}
public class Server {
private static final int PORT = 27012;
private static DatagramSocket sckt;
private static DatagramPacket in,out;
private static byte[] buffer;
private static HashMap<String,User> users;
public static void main(String[] args) {
try{
System.out.println("Opening port...");
sckt = new DatagramSocket(PORT);
users = new HashMap<String,User>();
}
catch(SocketException e){
System.out.println("Port connection failed!");
System.exit(1);
}
handleClient();
}
private static void sendMsg(InetAddress addr, int port, String msg){
try{
out = new DatagramPacket(msg.getBytes(),msg.length(),addr,port);
sckt.send(out);
}catch(IOException e){
e.printStackTrace();
}
}
private static void handleClient(){
try{
String msgIn,msgOut="",senderNick;
do{
buffer = new byte[256];
in = new DatagramPacket(buffer,buffer.length);
sckt.receive(in);
InetAddress clientAddress = in.getAddress();
int clientPort = in.getPort();
msgIn = new String(in.getData(),0,in.getLength());
//print msgIn
//System.out.println(msgIn);
senderNick = msgIn.substring(0,msgIn.indexOf(" "));
msgIn = msgIn.substring(msgIn.indexOf(" ")+1);
if(msgIn.equals("/connect")){
//String nick = msgIn.substring(msgIn.indexOf(" ") + 1);
System.out.println(senderNick);
if(users.containsKey(senderNick)){
msgOut = "Nick already in use!";
}
else{
users.put(senderNick, new User(clientAddress,clientPort));
msgOut = "Connected!";
}
sendMsg(clientAddress,clientPort,msgOut);
}
else if(msgIn.equals("/list")){
Set userNames;
userNames = users.keySet();
msgOut = "Users : \n";
msgOut += userNames.toString();
sendMsg(clientAddress,clientPort,msgOut);
}
else if(msgIn.startsWith("/msg")){
String tmp = msgIn.substring(msgIn.indexOf(" ")+1);
String receiverName = tmp.substring(0,tmp.indexOf(" "));
String message = tmp.substring(tmp.indexOf(" ")+1);
if(!users.containsKey(receiverName)){
msgOut = "User " + receiverName + " not found!";
sendMsg(clientAddress,clientPort,msgOut);
}
else{
User receiver = users.get(receiverName);
msgOut = "Message from "+ senderNick +" : "+message;
sendMsg(clientAddress,clientPort,"Message Sent!");
sendMsg(receiver.addr,receiver.port,msgOut);
}
}
else if(msgIn.startsWith("/nick")){
String newNick = msgIn.substring(msgIn.indexOf(" ")+1);
if(users.containsKey(newNick)){
msgOut = "Nick already in use!";
}
else{
users.put(newNick,users.get(senderNick));
users.remove(senderNick);
msgOut = "Nick changed!";
}
sendMsg(clientAddress,clientPort,msgOut);
}
else if(msgIn.equals("/disconnect")){
users.remove(senderNick);
}
//out = new DatagramPacket(msgOut.getBytes(),msgOut.length(),clientAddress,clientPort);
//sckt.send(out);
}while(true);
}
catch(IOException e){
e.printStackTrace();
}
finally{
System.out.println("Closing connection.");
sckt.close();
}
}
}
客户 ：
package chat;
import java.io.*;
import java.net.*;
import java.util.Scanner;
public class Client {
private static InetAddress host;
private static final int PORT = 27012;
private static DatagramSocket sckt;
private static DatagramPacket in, out;
private static byte[] buffer;
private static String nick;
static class MessageListener implements Runnable {
//DatagramPacket in;
//byte[] buffer;
String reply;
public void run() {
do{
try{
buffer = new byte[256];
in = new DatagramPacket(buffer,buffer.length);
sckt.receive(in);
reply = new String(in.getData(),0,in.getLength());
System.out.println("SERVER> "+reply);
}
catch(IOException e){
e.printStackTrace();
}
}while(true);
}
}
public static void main(String[] args) {
try {
host = InetAddress.getLocalHost();
} catch (UnknownHostException e) {
System.out.println("Host not found!");
System.exit(1);
}
connect();
}
private static void sendMsg(String msg) {
try {
out = new DatagramPacket(msg.getBytes(), msg.length(), host, PORT);
sckt.send(out);
} catch (IOException e) {
e.printStackTrace();
}
}
private static void connect() {
Scanner sc = new Scanner(System.in);
try {
buffer = new byte[256];
sckt = new DatagramSocket();
String reply = "";
do {
System.out.println("Name: ");
nick = sc.nextLine();
sendMsg(nick + " /connect");
in = new DatagramPacket(buffer, buffer.length);
sckt.receive(in);
reply = new String(in.getData(), 0, in.getLength());
System.out.println("SERVER> " + reply);
} while (!reply.equals("Connected!"));
accessServer();
} catch (IOException e) {
e.printStackTrace();
}
}
private static void accessServer() {
try {
sckt = new DatagramSocket();
Scanner sc = new Scanner(System.in);
String msg = "", reply = "";
Thread myT = new Thread(new MessageListener());
myT.start();
do {
System.out.print("Enter Message: ");
msg = sc.nextLine();
if (!msg.equals("/quit")) {
buffer = new byte[256];
sendMsg(nick + " " + msg);
} else {
sendMsg(nick + " /disconnect");
}
} while (!msg.equals("/quit"));
sc.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
System.out.println("Connection closing...");
sckt.close();
}
}
}
我希望能够向单个用户或所有用户发送消息，但问题是我无法在客户端上接收消息，因为就目前而言，客户端仅在向客户端发送消息后才会收到消息服务器。所以我的想法是使用一个线程来持续监听来自服务器的消息，但它不起作用。最简单的方法是什么？