如何在TCP Java应用程序中创建备份服务器，

Question

我有一个具有TCP Server的Java应用程序，它可以处理客户端请求。现在，我想创建一个TCP备份服务器，以便在TCP服务器出现故障时，备份服务器从TCP服务器发生故障的那一刻继续并处理客户端请求。

这怎么办？

我有一个客户端和一个服务器。

这是我现在的TCP Server代码。

import java.net.*;
import java.io.*;
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
import javax.script.ScriptException;

public class TCPServer {
        static ScriptEngineManager mgr;
        static ScriptEngine engine;
    public static void main(String args[]) {
        mgr = new ScriptEngineManager();
        engine = mgr.getEngineByName("js");
        try {
            int serverPort = 7896; // the server port
            ServerSocket listenSocket = new ServerSocket(serverPort);

            while (true) {
                System.out.println("Server is ready and waiting for requests .... ");
                Socket clientSocket = listenSocket.accept();
                System.out.println("request received from client with IP : " + clientSocket.getInetAddress());
                System.out.println("port of client : " + clientSocket.getPort());
                Thread c = new Connection(clientSocket);

            }
        } catch (IOException e) {
            //if already in use then redirect the request to backup server
            System.out.println("Listen socket:" + e.getMessage());
        }
    }
}

class Connection extends Thread {

    DataInputStream in;
    DataOutputStream out;
    Socket clientSocket;

    public Connection(Socket aClientSocket) {
        try {
            clientSocket = aClientSocket;
            in = new DataInputStream(clientSocket.getInputStream());
            out = new DataOutputStream(clientSocket.getOutputStream());
            this.start();

        } catch (IOException e) {
            System.out.println("Connection:" + e.getMessage());
        }
    }

    public void run() { 

        //send client request to bacckup server, with client IP adddress and port number
        //BackupTCPServer bus = new BackupTCPServer();
        //bus.clientIP = clientSocket.getInetAddress();
        //bus.clientPort = clientSocket.getPort();
        //System.out.println(bus);
        try {


            String s = in.readUTF();
            //bus.Expressionsbackup.add(s);
            String exp = "";
            int res = 0;
            while (s != null) {
                TCPServer.engine.put("i", 2);
                TCPServer.engine.put("j", 4);
                exp =s;
                Object result = TCPServer.engine.eval(exp);
                double st = (Double)result;
                out.writeUTF(Double.toString(st));
                //bus.expressionevaluated++;

                s = in.readUTF();
            }




        }
        catch (ScriptException se) {
            System.out.println("SE:" + se.getMessage());
        } 
        catch (EOFException e) {
            System.out.println("EOF:" + e.getMessage());
        } catch (IOException e) {
            System.out.println("readline:" + e.getMessage());
        } finally {
            try {
                clientSocket.close();
            } catch (Exception e) {
                /*close failed*/
            }
        }
    }
}