创建一个 java 服务器套接字，使用线程池等待来自客户端的消息

Question

@FXML
private TextArea textarea;
@FXML
private ImageView imagev;

@Override
public void initialize(URL url, ResourceBundle resourceBundle) {
    Serverth Server = new Serverth();
    Server.start();
}


class Serverth extends Thread {
    @Override
    public void run() {
        try {
            final int NUM_THREAD = 99;


            ServerSocket socket = new ServerSocket(8078);
            ExecutorService exec = Executors.newFixedThreadPool(NUM_THREAD);
            System.out.println("SERVER SOCKET CREATED");


            while (!isInterrupted()) {
                Socket in = socket.accept();
                Runnable r = new ThreadedHandler(in);
                exec.execute(r);

            }
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }

    }
}

class ThreadedHandler implements Runnable {

    private Socket incoming;

    public ThreadedHandler(Socket in) {
        incoming = in;
    }

    public void run() {
        try {
            try {
                ObjectInputStream is=new ObjectInputStream(incoming.getInputStream());

                while(true) {
                    if (is.available() > 0) {
                        String line = is.readUTF();

                        textarea.appendText("\n" + "[" + new java.util.Date() + "] : " + line);

                        if (line.contains("inviato")) {
                            Object obj = is.readObject();
                            Email ema = (Email) obj;
                            try {
                                SimpleDateFormat formatter = new SimpleDateFormat("dd-M-yyyy-hh-mm-ss");
                                FileOutputStream fileOut = new FileOutputStream("src/Server/" + ((Email) obj).getDestinat() + "/" +  formatter.format(((Email) obj).getData()) + ".txt");
                                ObjectOutputStream objectOut = new ObjectOutputStream(fileOut);
                                objectOut.writeObject(ema);
                                objectOut.flush();
                                objectOut.close();
                                System.out.println("The Object  was succesfully written to a file");

                            } catch (Exception ex) {
                                ex.printStackTrace();
                            }

                        }

                    }
                }
                } catch(IOException ex) {
                ex.printStackTrace();
            }

        } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } finally {
            try {
                incoming.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }

        }
    }
}

在运行方法中（在 Serveth class 中），我创建了一个服务器套接字并调用了 exec.execute 方法。在运行方法中（在 ThreadedHandler class 中），服务器正在等待来自客户端的消息（在这种特定情况下，它会创建一个新的 .txt 文件，但这并不重要）。一切正常，但会导致过度使用 CPU 和滞后！！！

Answer 1

InputSteam.available 方法 returns 一个值立即告诉你没有字节可供读取，所以这段代码运行一个非常 "hot" 自旋循环：

            while(true) {
                if (is.available() > 0) {
                    ...
                }
            }

available 方法很少有用，而且经常会给出令人困惑的结果（参见示例 inputstream.available() is 0 always）。我建议你完全去掉 if 语句：

            while(true) {
                String line = is.readUTF();

                textarea.appendText("\n" + "[" + new java.util.Date() + "] : " + line);
                ...
            }

您的代码无法正常退出循环。您可能希望为客户端添加一种与服务器断开连接的机制。

创建一个 java 服务器套接字，使用线程池等待来自客户端的消息

create a java server socket that waits for messages from client using Thread Pool

java

multithreading

sockets

message

runnable