TextArea内按Enter发送消息并清空内容 换行

//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);
}
});
}
}