Ext 表单控件为空时自动加星号 *

Ext.form.Field.prototype.initComponent = function(){
if(this.allowBlank==false){
this.fieldLabel="*"+this.fieldLabel;
}
Ext.form.Field.superclass.initComponent.call(this);
this.addEvents(

'focus',

'blur',

'specialkey',

'change',

'invalid',

'valid'
);
}