RCP：解决Navigator快捷键不生效的问题

自己扩展CNF之后，导航栏的删除、复制、黏贴等快捷键失效了，在网上搜索了半天，结果最终不如自己看源码。

本篇文章的主要目的不止于解决快捷键失效，更在于如何处理类似的问题，如何利用debug快速定位。这种解决问题的思路能帮助我们更加理解他人的代码，快速熟悉一套陌生的框架。

1、理解问题的本质，为什么按键不生效？

在解决快捷键失效问题之前，我们需要理解快捷键是如何生效的。

为了更直观的理解，请使用debug模式打开一个新的Eclipse IDE，然后，对org.eclipse.jdt.internal.ui.refactoring.reorg.CopyToClipboardAction这个类的run方法加上断点。在新的EclipseIDE的Package Explorer上选中一个节点，按CTRL+C

在DEBUG视图中显示如下图所示：

RCP：解决Navigator快捷键不生效的问题

我们过一眼这些类名和方法名，如果你是个有经验的程序员，那么，你应当能敏感的发现WorkbenchKeyboard就是是你需要的那个类。

我们看看executeCommand方法，关键代码标记上了红色。

    final boolean executeCommand(final Binding binding, final Event trigger)
            throws CommandException {
        final ParameterizedCommand parameterizedCommand = binding
                .getParameterizedCommand();

        if (DEBUG) {
            Tracing.printTrace("KEYS", //$NON-NLS-1$
                    "WorkbenchKeyboard.executeCommand(commandId = '" //$NON-NLS-1$
                            + parameterizedCommand.getId() + "', parameters = " //$NON-NLS-1$
                            + parameterizedCommand.getParameterMap() + ')');
        }

        // Reset the key binding state (close window, clear status line, etc.)
        resetState(false);

        // Dispatch to the handler.
        final IHandlerService handlerService = (IHandlerService) workbench
                .getService(IHandlerService.class);
        final Command command = parameterizedCommand.getCommand();
        final boolean commandDefined = command.isDefined();
        final boolean commandHandled = command.isHandled();
        command.setEnabled(handlerService.getCurrentState());
        final boolean commandEnabled = command.isEnabled();

        if (DEBUG && DEBUG_VERBOSE) {
            if (!commandDefined) {
                Tracing.printTrace("KEYS", "    not defined"); //$NON-NLS-1$ //$NON-NLS-2$
            } else if (!commandHandled) {
                Tracing.printTrace("KEYS", "    not handled"); //$NON-NLS-1$ //$NON-NLS-2$
            } else if (!commandEnabled) {
                Tracing.printTrace("KEYS", "    not enabled"); //$NON-NLS-1$ //$NON-NLS-2$
            }
        }

        try {
            handlerService.executeCommand(parameterizedCommand, trigger);
        } catch (final NotDefinedException e) {
            // The command is not defined. Forwarded to the IExecutionListener.
        } catch (final NotEnabledException e) {
            // The command is not enabled. Forwarded to the IExecutionListener.
        } catch (final NotHandledException e) {
            // There is no handler. Forwarded to the IExecutionListener.
        }

        /*
         * Now that the command has executed (and had the opportunity to use the
         * remembered state of the dialog), it is safe to delete that
         * information.
         */
        if (keyAssistDialog != null) {
            keyAssistDialog.clearRememberedState();
        }

        return (commandDefined && commandHandled);
    }

我们发现了binding这个对象。binding的注释如下：

org.eclipse.jface.bindings.Binding



A binding is a link between user input and the triggering of a particular command. The most common example of a binding is a keyboard shortcut, but there are also mouse and gesture bindings.

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