Java网络编程socket，为何我的服务器打不开？

初学Java网络编程socket，写了个服务器，但是打不开，求指导。代码如下

public class Test2_2Server extends Application{
    //创建显示文本域
    private TextArea area = new TextArea();

    public void start(Stage primaryStage){
        area.setEditable(false);

        Scene scene = new Scene(new ScrollPane(area), 450,300);
        primaryStage.setTitle("Test2_2Server");
        primaryStage.setScene(scene);
        primaryStage.show();

        try {
            //创建一个服务器套接字
            ServerSocket serverSocket = new ServerSocket(8800);
            Platform.runLater(() ->
                area.appendText("Server started at " + new Date() + '\n'));

            int clientNo = 1;
            while (true){
                //监听
                Socket socket = serverSocket.accept();

                area.appendText("Starting thread for client " + clientNo + " at " + new Date() + '\n');

                //获取客户端地址
                InetAddress inetAddress = socket.getInetAddress();
                area.appendText("Client " + clientNo + "'s host name is " + inetAddress.getHostName() + '\n');
                area.appendText("Client " + clientNo + "'s IP Address is " + inetAddress.getHostAddress() + '\n');

                //创建进程
                HandleAClient task = new HandleAClient(socket);

                //开始运行
                new Thread(task).start();

                //客户端数加一
                clientNo++;
            }
        }
        catch(IOException ex) {
            System.err.println(ex);
        }


    }

    public static void main(String[] args) {
        launch(args);
    }

    //服务器端的任务类
    class HandleAClient implements Runnable{
        private Socket socket;

        public HandleAClient(Socket socket1){
            this.socket = socket1;
        }

        public void run(){
            try {
                //创建输入输出流
                DataInputStream inputFromClient = new DataInputStream(socket.getInputStream());
                DataOutputStream outputToClient = new DataOutputStream(socket.getOutputStream());

                while (true){
                    //获取客户端数据
                    double annualInterestRate = inputFromClient.readDouble();
                    int numberOfYears = inputFromClient.readInt();
                    double loanAmount = inputFromClient.readDouble();

                    //计算偿还额
                    double totalPayment = loanAmount * Math.pow(1 + annualInterestRate * 0.01, numberOfYears);
                    double monthlyPayment = totalPayment / numberOfYears / 12;
                    //将数据传送至客户端
                    outputToClient.writeDouble(monthlyPayment);
                    outputToClient.writeDouble(totalPayment);
                    //输出
                    Platform.runLater(() ->{
                        area.appendText("Annual Interest Rate:" + annualInterestRate + '\n');
                        area.appendText("Number Of Year:" + numberOfYears + '\n');
                        area.appendText("Loan Amount:" + loanAmount + '\n');

                        area.appendText("Monthly Payment:" + monthlyPayment + '\n');
                        area.appendText("Total Payment:" + totalPayment + '\n');
                    });
                }
            }
            catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }
}