使它们成为getter和setter.没有其他方法可以获取有关更改的通知:

Make them getters and setters. There is no other way to get notified about changes:

export class MessagesPage  {

    @ViewChild(Content) content: Content;

    public message  = '';
    public messages = [];

    private _state = 'general';
    public get state() { return this._state; }
    public set state(value:string) { 
      this._state = value;
      console.log('state changed', this._state);
    }
}