我正在开发一个 Java 客户端/服务器聊天应用程序，它允许局域网内的用户在他们之间聊天。
在服务器应用程序中，我有一个主类，它在客户端连接到服务器时创建一个不同的线程。所以，基本上我保持打开一个 TCP 连接，每个客户端都在一个单独的线程上运行。
我在发送消息时遇到问题。当用户向服务器发送一条新消息+它的目标时，服务器必须找到与目标用户有连接的线程并将该消息发送给他。我该怎么做呢。我已将每个线程与一个用户对象相关联，因此我需要执行 findThreadByUser(user) 之类的操作，并在获取引用后调用发送消息的方法。我该怎么做呢？
下面是实现 Runnable 的 ConnectionHandler 类的一部分。我想访问该类的特定实例，更具体地说是sendToClient(String message)它末尾的方法（外部运行方法）。我尝试使用 HashMap 来存储用户和线程，但我无法访问该方法sendToClient(String message)
public class ConnectionHandler implements Runnable {
protected Socket socket;
private ServerData serverData;
private User currentUser;
BufferedReader inFromClient;
PrintStream outToClient;
String clientSentence;
String peerIp;
String peerHostName;
public ConnectionHandler(Socket socketToHandle, ServerData serverData) {
socket = socketToHandle;
this.serverData = serverData;
inFromClient = null;
outToClient = null;
currentUser = null;
clientSentence = " ";
}
@Override
public void run() {
peerIp = socket.getInetAddress().getHostAddress();
peerHostName = socket.getInetAddress().getHostName();
try {
outToClient = new PrintStream(socket.getOutputStream(), true);
/* Create a reading stream to the socket */
inFromClient = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (IOException ex) {
Logger.getLogger(ConnectionHandler.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Error creating buffered handles.");
}
System.out.println("Handling connection to client at " + peerIp + " --");
Runnable r1 = new Runnable() {
public void run() {
while (true) {
try {
/* Read client's message through the socket's input buffer */
clientSentence = inFromClient.readLine();
} catch (IOException e) {
System.out.println(socket.getInetAddress() + "-" + peerIp + " broke the connection.");
break;
}
/* Output to screen the message received by the client */
System.out.println("Message Received: " + clientSentence);
List<String> processedClientSentence = ClientMessageProcessor.process(clientSentence);
if (processedClientSentence.get(0).equals(new String("LOGIN"))) {
String result = ServerActions.login(peerIp, peerHostName, processedClientSentence.get(1), serverData);
if (result.equals("success")) {
currentUser = serverData.getUserByIP(peerIp);
outToClient.println("USERS \"" + ServerActions.getUsers(serverData) + "\"");
} else {
outToClient.println("ERROR \'" + result + "\'");
}
} else if (processedClientSentence.get(0).equals(new String("GETUSERS"))) {
outToClient.println("USERS \"" + ServerActions.getUsers(serverData) + "\"");
} else if (processedClientSentence.get(0).equals(new String("USERINFO"))) {
} else if (processedClientSentence.get(0).equals(new String("MESSAGE"))) {
ServerActions.sendMessage(currentUser/*.getUserName()*/, processedClientSentence.get(1), processedClientSentence.get(2), serverData);
} else if (processedClientSentence.get(0).equals(new String("LOGOUT"))) {
} else {
}
}
}
};
new Thread(r1).start();
}
public void sendToClient(String message) {
outToClient.println(message);
}
}