带套接字的Java客户端/服务器应用程序？

Question

我正在编写一个将被另一种语言(matlab)调用的java包.如果我的matlab进程结束,我希望Java进程继续运行.每当matlab再次启动时,它应该能够与现有的运行进程通信.所以我认为我需要让Java应用程序通过客户端/服务器模型中的套接字进行通信.我设想有一套简单的功能:

• startServer(主机,端口)
• runCommand(服务器,命令......)
• stopServer(主机,端口)

我之前从未做过这样的事情.我是以正确的方式思考它,还是有一种更简单的方法来构建一个可以独立于其父进程运行的应用程序？什么是最好的现代方式(例如,有没有好的Apache包)？任何人都可以提供一个简单的演示或指向我通过套接字与进程通信的教程吗？

[编辑]为了澄清一下,matlab能够实例化一个java对象并在其自身中运行java代码.因此,matlab中的startServer()函数将运行java代码,该代码将检查java进程是否已在该端口上运行,如果没有,则启动服务器进程.

我并不依赖于使用套接字(如果不是很明显,我主要是一个matlab开发人员),所以如果有更容易的东西,我就是为了它.我只需要能够独立于matlab运行,但让matlab控制这些进程(通过java).

Answer 1

服务器侦听连接.当客户端建立连接时.客户端可以发送数据.在当前示例中,客户端发送消息"Hi my server".要终止连接,客户端会发送消息"bye".然后服务器也发送消息"再见".最后,连接结束,服务器等待另一个连接.这两个程序应该在同一台机器上运行.但是,如果要在两台不同的计算机上运行它们,您可以简单地将地址"localhost"更改为运行服务器的计算机的IP地址.

服务器

import java.io.*;
import java.net.*;
public class Provider{
    ServerSocket providerSocket;
    Socket connection = null;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;
    Provider(){}
    void run()
    {
        try{
            //1. creating a server socket
            providerSocket = new ServerSocket(2004, 10);
            //2. Wait for connection
            System.out.println("Waiting for connection");
            connection = providerSocket.accept();
            System.out.println("Connection received from " + connection.getInetAddress().getHostName());
            //3. get Input and Output streams
            out = new ObjectOutputStream(connection.getOutputStream());
            out.flush();
            in = new ObjectInputStream(connection.getInputStream());
            sendMessage("Connection successful");
            //4. The two parts communicate via the input and output streams
            do{
                try{
                    message = (String)in.readObject();
                    System.out.println("client>" + message);
                    if (message.equals("bye"))
                        sendMessage("bye");
                }
                catch(ClassNotFoundException classnot){
                    System.err.println("Data received in unknown format");
                }
            }while(!message.equals("bye"));
        }
        catch(IOException ioException){
            ioException.printStackTrace();
        }
        finally{
            //4: Closing connection
            try{
                in.close();
                out.close();
                providerSocket.close();
            }
            catch(IOException ioException){
                ioException.printStackTrace();
            }
        }
    }
    void sendMessage(String msg)
    {
        try{
            out.writeObject(msg);
            out.flush();
            System.out.println("server>" + msg);
        }
        catch(IOException ioException){
            ioException.printStackTrace();
        }
    }
    public static void main(String args[])
    {
        Provider server = new Provider();
        while(true){
            server.run();
        }
    }
}

客户端

import java.io.*;
import java.net.*;
public class Requester{
    Socket requestSocket;
    ObjectOutputStream out;
    ObjectInputStream in;
    String message;
    Requester(){}
    void run()
    {
        try{
            //1. creating a socket to connect to the server
            requestSocket = new Socket("localhost", 2004);
            System.out.println("Connected to localhost in port 2004");
            //2. get Input and Output streams
            out = new ObjectOutputStream(requestSocket.getOutputStream());
            out.flush();
            in = new ObjectInputStream(requestSocket.getInputStream());
            //3: Communicating with the server
            do{
                try{
                    message = (String)in.readObject();
                    System.out.println("server>" + message);
                    sendMessage("Hi my server");
                    message = "bye";
                    sendMessage(message);
                }
                catch(ClassNotFoundException classNot){
                    System.err.println("data received in unknown format");
                }
            }while(!message.equals("bye"));
        }
        catch(UnknownHostException unknownHost){
            System.err.println("You are trying to connect to an unknown host!");
        }
        catch(IOException ioException){
            ioException.printStackTrace();
        }
        finally{
            //4: Closing connection
            try{
                in.close();
                out.close();
                requestSocket.close();
            }
            catch(IOException ioException){
                ioException.printStackTrace();
            }
        }
    }
    void sendMessage(String msg)
    {
        try{
            out.writeObject(msg);
            out.flush();
            System.out.println("client>" + msg);
        }
        catch(IOException ioException){
            ioException.printStackTrace();
        }
    }
    public static void main(String args[])
    {
        Requester client = new Requester();
        client.run();
    }
}