MVP For GWT 系列资料转载三：How to reduce startup time with gwt-presenter

源文转自：How to reduce startup time with gwt-presenter

 

I’ve finally figured out a way to trim down the initial load time for my app. I’m not quite ready for GWT 2, runAsync(), or the new Place API in gwt-presenter, but I’ve been able to cut my initial load time significantly (from 14s to 2s) by doing some lazy loading within my presenters and views. In a nutshell, here’s how it works:

 

I now do nothing in the constructor and bind() methods of each presenter and view.

Instead, I’ve created a new method onFirstRequest() in my base presenter. It gets called on the first invocation of onPlaceRequest(), which simply increments a counter in a class field to keep track.

I’ve added an init() method to the base presenter’s Display interface. It gets called by onFirstRequest(). I moved all widget creation in my views from the constructor and onBind() methods into this init() method instead, thus delaying all widget creation until the first time the view is accessed.

Following a suggestion from Per Wiklander in a recent comment to this blog, I noop’d the addWidget() method in my WidgetContainerDisplay class. This method gets called for each presenter that you add to a WidgetContainerPresenter, which doesn’t make sense for the way I’m using the container (I show only one view at a time). The addWidget() method is not used for anything else.

Since this particular scheme utilizes onPlaceRequest() to keep track of the first invocation, it will only work if you first reveal a view by firing the corresponding PlaceRequentEvent, either in code or by visiting the place URL.