Eclipse RCP：如何防止多个RCP实例启动？

Question

我在http://eclipse.geekyramblings.net/2010/12/14/preventing-multiple-instances/上读到了如何防止多个RCP实例被启动的方法。但是当我将我的RCP（它是基于“Hello RCP”模板的简单RCP）制作成可执行文件并尝试启动它时，它会抛出这个错误。

java.io.IOException: The location has not been set.
    at org.eclipse.core.runtime.internal.adaptor.BasicLocation.lock(BasicLocation.java:174)
    at testrcp.Application.start(Application.java:43)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:369)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:619)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1407)

我正在使用Eclipse Java EE IDE for Web Developers.

版本：Helios Service Release 1 构建编号：20100917-0705

这是我的Application.java文件中的代码：

package testrcp;

import org.eclipse.core.runtime.Platform;
import org.eclipse.equinox.app.IApplication;
import org.eclipse.equinox.app.IApplicationContext;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.osgi.service.datalocation.Location;
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 {
        Display display = PlatformUI.createDisplay();

        int exitCode = IApplication.EXIT_OK;

        Location instanceLocation = Platform.getInstanceLocation();

        if (!instanceLocation.lock()) {
            MessageDialog.openError(new Shell(display), "App Title",
            "Another instance of the Application is currently running.");
        } else {

            int returnCode = PlatformUI.createAndRunWorkbench(display,
                    new ApplicationWorkbenchAdvisor());
            switch (returnCode) {
            case PlatformUI.RETURN_RESTART :
                exitCode = IApplication.EXIT_RESTART;
                break;
            default :
                exitCode = IApplication.EXIT_OK;
            }
        }

        instanceLocation.release();

        display.dispose();

        return exitCode;
    }
    /* (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();
            }
        });
    }
}

非常感谢您提供的帮助解决这个问题或者任何建议。谢谢，Abbas。

- Abbas

Answer 1

我通过添加这行代码使其正常工作

instanceLocation.getURL();

之后

Location instanceLocation = Platform.getInstanceLocation();

但是请注意，这并不能防止它从存在RCP可执行文件的不同文件夹中启动...有没有办法对此进行检查？

- Abbas

---

设置 osgi.instance.area.default 属性也可以解决问题：-Dosgi.instance.area.default=@user.dir/workspace - Jarek Przygódzki

Answer 2

当您启动应用程序时，还可以打开服务器套接字。如果您打开另一个实例，请与服务器通信。如果可以通信，则可以打开运行实例，留下一个应用程序实例。

更详细的信息在这里

- Kathir