问如何在flex4中获取文本区域中当前光标位置下的单词

EN

public function currentWord(ta:RichEditableText):String
{
    var wordBegin:int = ta.selectionAnchorPosition;
    var wordEnd:int = ta.selectionAnchorPosition;
    // while the previous char is a word character... let's find out where the word starts
    while (ta.text.charAt(wordBegin-1).search(/\w+/) > -1 && wordBegin > 0 ) { wordBegin--; }
    // while the next char is a word character... let's find out where the word ends
    while (ta.text.charAt(wordEnd).search(/\w+/) > -1 && wordEnd > 0 ) { wordEnd++; }
    return ta.text.substring(wordBegin, wordEnd);
}