问题解答：Eclipse中怎样判断Editor中光标的位置，并找到光标周围代码，这样的事件在哪里写？

一、先说触发方式：
有样学样法则。
首先，查找调用org.eclipse.ui.texteditor.AbstractTextEditor.setAction(String, IAction)的地方：
搜索结果：
org.eclipse.ui.texteditor - src - org.eclipse.ui.workbench.texteditor
AbstractTextEditor
createAccessibilityActions()
createActions() (44 matches)重点看这里。见下文代码一
createNavigationActions() (8 matches)
createUndoRedoActions() (2 matches)
getAction(String)
registerUndoRedoAction(String, OperationHistoryActionHandler)


代码一（这个action，最基础的接口是IAction，也可以从TextEditorAction派生）
        protected void createActions() {

        ResourceAction action;

                action= new TextOperationAction(EditorMessages.getBundleForConstructedKeys(), "Editor.Cut.", this, ITextOperationTarget.CUT); //$NON-NLS-1$
                action.setHelpContextId(IAbstractTextEditorHelpContextIds.CUT_ACTION);
                action.setActionDefinitionId(IWorkbenchActionDefinitionIds.CUT);
                setAction(ITextEditorActionConstants.CUT, action);

注释：
1、那么action如何触发呢？与setActionDefinitionId有关，这个ID需要通过org.eclipse.ui.commands扩展点扩展（这个扩展点中指定的id就是触发这个动作的command id）。
2、command id有了，command如何触发呢？需要菜单、快捷键、上下文菜单、按钮、等等。那么把你想要做的事情关联到这个id就 ok了。


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二、现在说光标，要在自己的action run()的时候：
        public void run()
        {
                ITextEditor editor= getTextEditor();
                ISelection section = editor.getSelectionProvider().getSelection();
                int Selectedoffset=0;
                if(section instanceof ITextSelection)
                        Selectedoffset = ((ITextSelection)section).getOffset();
                IDocument document = editor.getDocumentProvider().getDocument(editor.getEditorInput());
               
                try {
                                 IRegion selectdLineRegion = document.getLineInformationOfOffset(Selectedoffset);
                                 String lineString = document.get(selectdLineRegion.getOffset(), selectdLineRegion.getLength());

重点在ITextSelection，和 getDocument
public interface ITextSelection extends ISelection {

        /**
         * Returns the offset of the selected text.
         *
         * @return the offset of the selected text
         */
        int getOffset();

        /**
         * Returns the length of the selected text.
         *
         * @return the length of the selected text
         */
        int getLength();

        /**
         * Returns number of the line containing the offset of the selected text.
         * If the underlying text has been changed between the creation of this
         * selection object and the call of this method, the value returned might
         * differ from what it would have been at the point of creation.
         *
         * @return the start line of this selection or <code>-1</code> if there is no valid line information
         */
        int getStartLine();//哈哈。O(∩_∩)O哈哈~

        /**
         * Returns the number of the line containing the last character of the selected text.
         * If the underlying text has been changed between the creation of this
         * selection object and the call of this method, the value returned might
         * differ from what it would have been at the point of creation.
         *
         * @return the end line of this selection or <code>-1</code> if there is no valid line information
         */
        int getEndLine();

        /**
         * Returns the selected text.
         * If the underlying text has been changed between the creation of this
         * selection object and the call of this method, the value returned might
         * differ from what it would have been at the point of creation.
         *
         * @return the selected text or <code>null</code> if there is no valid text information
         */
        String getText();
}