Eclipse源碼閱讀:GotoTypeAction

Go To Type是Eclipse的Navigate菜單下的一個子菜單的功能，如下所示：

大部分內容和{Eclipse源碼閱讀：Go To Resource點擊打開鏈接}一樣.

這裏直接貼同分析的核心代碼,重點部分添加了中文註釋.

/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.packageview;

import org.eclipse.swt.widgets.Shell;

import org.eclipse.jface.action.Action;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.jface.dialogs.ProgressMonitorDialog;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;

import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.dialogs.SelectionDialog;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.core.search.SearchEngine;

import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.ui.IJavaElementSearchConstants;
import org.eclipse.jdt.ui.JavaElementLabels;
import org.eclipse.jdt.ui.JavaUI;

import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.util.ExceptionHandler;

class GotoTypeAction extends Action {

	private PackageExplorerPart fPackageExplorer;

	GotoTypeAction(PackageExplorerPart part) {
		super();
		setText(PackagesMessages.GotoType_action_label);
		setDescription(PackagesMessages.GotoType_action_description);
		fPackageExplorer= part;
		PlatformUI.getWorkbench().getHelpSystem().setHelp(this, IJavaHelpContextIds.GOTO_TYPE_ACTION);
	}

	public void run() {
		Shell shell= JavaPlugin.getActiveWorkbenchShell();
		SelectionDialog dialog= null;
		//本質上是構建了FilteredTypesSelectionDialog對話框,可參考我的另一篇總結()
		try {
			dialog= JavaUI.createTypeDialog(shell, new ProgressMonitorDialog(shell),
				SearchEngine.createWorkspaceScope(), IJavaElementSearchConstants.CONSIDER_ALL_TYPES, false);
		} catch (JavaModelException e) {
			String title= getDialogTitle();
			String message= PackagesMessages.GotoType_error_message;
			ExceptionHandler.handle(e, title, message);
			return;
		}

		dialog.setTitle(getDialogTitle());
		dialog.setMessage(PackagesMessages.GotoType_dialog_message);
		if (dialog.open() == IDialogConstants.CANCEL_ID) {
			return;
		}

		Object[] types= dialog.getResult();
		if (types != null && types.length > 0) {
			gotoType((IType) types[0]);//只處理選中第一個元素
		}
	}

	private void gotoType(IType type) {
		// type.getAncestor獲得指定類型(int值在IJavaElement均有定義)的祖先
		ICompilationUnit cu= (ICompilationUnit) type.getAncestor(IJavaElement.COMPILATION_UNIT);
		IJavaElement element= null;
		if (cu != null) {
			element= cu.getPrimary();
		}
		else {
			element= type.getAncestor(IJavaElement.CLASS_FILE);
		}
		if (element != null) {
			PackageExplorerPart view= PackageExplorerPart.openInActivePerspective();
			if (view != null) {
				//在Package Explorer的樹結構中定位顯示
				view.selectReveal(new StructuredSelection(element));
				if (!element.equals(getSelectedElement(view))) {
					MessageDialog.openInformation(fPackageExplorer.getSite().getShell(),
						getDialogTitle(),
						Messages.format(PackagesMessages.PackageExplorer_element_not_present, JavaElementLabels.getElementLabel(element, JavaElementLabels.ALL_DEFAULT)));
				}
			}
		}
	}

	private Object getSelectedElement(PackageExplorerPart view) {
		return ((IStructuredSelection)view.getSite().getSelectionProvider().getSelection()).getFirstElement();
	}

	private String getDialogTitle() {
		return PackagesMessages.GotoType_dialog_title;
	}
}