完美实现TextArea内按Enter发送消息并清空内容

//下面三个变量用来保存KEY_DOWN事件时键盘的状态
 
var shiftKey:Boolean;
 
var ctrlKey:Boolean;
 
var keyCode:int;
 
var messageInput:TextArea;
 
messageInput.addEventListener(KeyboardEvent.KEY_DOWN,onKeyDown);
 
messageInput.addEventListener(TextEvent.TEXT_INPUT,onTextInput);
 
private function onKeyDown(e:KeyboardEvent):void{
 
//如果按下Enter时还按下Shift/Ctrl，则换行
 
if( e.keyCode==Keyboard.ENTER && (e.shiftKey || e.ctrlKey) ){
 
callLater(function():void{ //注意这个callLater
 
var msg:String = messageInput.text;
 
var part1:String = msg.substring(0, messageInput.selectionBeginIndex);
 
var part2:String = msg.substring(messageInput.selectionEndIndex, 0x7fffffff);
 
var selIndex:int = messageInput.selectionBeginIndex + 1;
 
messageInput.text = part1 + "\n" + part2;
 
messageInput.setSelection(selIndex,selIndex);
 
});
 
keyCode = -1; //标识本次按键不需要TEXT_INPUT事件配合处理
 
return;
 
}
 
shiftKey = e.shiftKey;
 
ctrlKey = e.ctrlKey;
 
keyCode = e.keyCode;
 
}
 
private function onTextInput(evt:TextEvent):void{
 
if(keyCode == -1){
 
return;
 
}
 
if(keyCode==Keyboard.ENTER && !shiftKey && !ctrlKey){
 
evt.preventDefault();
 
callLater(function():void{
 
//sendMessage()即为发送消息的方法，它应该返回一个Boolean值，以此来决定是否清空消息框
 
if( sendMessage(messageInput.text) ){
 
messageInput.text = "";
 
messageInput.htmlText = "";
 
messageInput.setSelection(0,0);
 
}
 
});
 
}
 
}