如何将 Eclipse-RCP 应用程序限制为单个实例?-Java问题

How to restrict Eclipse-RCP application to a single instance?(如何将 Eclipse-RCP 应用程序限制为单个实例?)

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问题描述

我想将我的 Eclipse-RCP 应用程序限制为单个实例.我的意思是，一旦用户第一次打开应用程序，它会监听一个端口，而对于第二次访问，它应该打开前一个实例，而不是显示诸如已经有一个实例正在运行"之类的警告消息

I would like to restrict my Eclipse-RCP application to a single instance. By this, I mean that once a user opens the application for the first time, it listens on a port and for the second access it should open the previous instance instead of showing a warning message like "already an instance is running"

我的 RCP 应用程序代码:

My RCP Application code:

ApplicationInstanceListener.java 接口代码

public interface ApplicationInstanceListener
{
    public void newInstanceCreated();
}

ApplicationInstanceManager.java 代码

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;


public class ApplicationInstanceManager {
        private static ApplicationInstanceListener subListener;

    /** Randomly chosen, but static, high socket number */
    public static final int SINGLE_INSTANCE_NETWORK_SOCKET = 2020;

    /** Must end with newline */
    public static final String SINGLE_INSTANCE_SHARED_KEY = "$$NewInstance$$
";

    /**
     * Registers this instance of the application.
     *
     * @return true if first instance, false if not.
     */
    public static boolean registerInstance() {
        // returnValueonerror should be true if lenient (allows app to run on network error) or false if strict.
        boolean returnValueonerror = true;
        // try to open network socket
        // if success, listen to socket for new instance message, return true
        // if unable to open, connect to existing and send new instance message, return false
        try {
            final ServerSocket socket = new ServerSocket(SINGLE_INSTANCE_NETWORK_SOCKET, 10, InetAddress
                    .getLocalHost());
           System.out.println("Listening for application instances on socket " + SINGLE_INSTANCE_NETWORK_SOCKET);
            Thread instanceListenerThread = new Thread(new Runnable() {
                public void run() {
                    boolean socketClosed = false;
                    while (!socketClosed) {
                        if (socket.isClosed()) {
                            socketClosed = true;
                        } else {
                            try {
                                Socket client = socket.accept();
                                BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
                                String message = in.readLine();
                                if (SINGLE_INSTANCE_SHARED_KEY.trim().equals(message.trim())) {
                                        System.out.println("Shared key matched - new application instance found");
                                    fireNewInstance();
                                }
                                in.close();
                                client.close();
                            } catch (IOException e) {
                                socketClosed = true;
                            }
                        }
                    }
                }
            });
            instanceListenerThread.start();
            // listen
        } catch (UnknownHostException e) {
                System.out.println(e.getMessage());
            return returnValueonerror;
        } catch (IOException e) {
                System.out.println("Port is already taken.  Notifying first instance.");
            try {
                Socket clientSocket = new Socket(InetAddress.getLocalHost(), SINGLE_INSTANCE_NETWORK_SOCKET);
                OutputStream out = clientSocket.getOutputStream();
                out.write(SINGLE_INSTANCE_SHARED_KEY.getBytes());
                out.close();
                clientSocket.close();
                System.out.println("Successfully notified first instance.");
                return false;
            } catch (UnknownHostException e1) {
                System.out.println(e.getMessage());
                return returnValueonerror;
            } catch (IOException e1) {
                System.out.println("Error connecting to local port for single instance notification");
                System.out.println(e1.getMessage());
                return returnValueonerror;
            }

        }
        return true;
    }

    public static void setApplicationInstanceListener(ApplicationInstanceListener listener) {
        subListener = listener;
    }

    private static void fireNewInstance() {
      if (subListener != null) {
        subListener.newInstanceCreated();
      }
  }
}

Application.java 代码

import org.eclipse.equinox.app.IApplication;
import org.eclipse.equinox.app.IApplicationContext;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.IWorkbench;
import org.eclipse.ui.PlatformUI;

/**
 * This class controls all aspects of the application's execution
 */
public class Application implements IApplication {

        /*
         * (non-Javadoc)
         *
         * @see org.eclipse.equinox.app.IApplication#start(org.eclipse.equinox.app.
         * IApplicationContext)
         */
        public Object start(IApplicationContext context) throws Exception {
                if (!ApplicationInstanceManager.registerInstance()) {
                        // instance already running.
                        System.out
                                        .println("Another instance of this application is already running.  Exiting.");
                        MessageDialog
                                        .openInformation(new Shell(), "Information",
                                                        "Another instance of this application is already running.  Exiting.");
                        System.exit(0);
                }
                Display display = PlatformUI.createDisplay();
                try {
                        int returnCode = PlatformUI.createAndRunWorkbench(display,
                                        new ApplicationWorkbenchAdvisor());
                        if (returnCode == PlatformUI.RETURN_RESTART)
                                return IApplication.EXIT_RESTART;
                        else
                                return IApplication.EXIT_OK;
                } finally {
                        display.dispose();
                }

        }

        /*
         * (non-Javadoc)
         *
         * @see org.eclipse.equinox.app.IApplication#stop()
         */
        public void stop() {
                if (!PlatformUI.isWorkbenchRunning())
                        return;
                final IWorkbench workbench = PlatformUI.getWorkbench();
                final Display display = workbench.getDisplay();
                display.syncExec(new Runnable() {
                        public void run() {
                                if (!display.isDisposed())
                                        workbench.close();
                        }
                });
        }
}

我采用了一个带有视图的简单 RCP 应用程序作为模板.上面的代码工作正常，但没有打开以前的实例，如 skype 或 windows 媒体播放器，尽管它显示如下所示的警报

I've taken a simple RCP application with view as a template. The above code works fine but doesn't open previous instance like skype or windows media player despite it shows an alert like below

如何在应用程序第二次运行时显示或打开之前的实例?

How can I show or open the previous instance upon second run of the application?