What are the principles of developing web-applications with action-based java frameworks?_问答_开发者

Background

I'm going to develop a new web-application with java. It's not very big or very complex and I have enough time until it'll "officially" start.

I have some JSF/Facelets development background (about half a year). And I also have some expirience with JSP+JSTL.

In self-educational purpose (and also in order to find the best solution) I want to prototype the new project with one of action-based frameworks. Actually, I will choose between Spring MVC and Stripes.

Problem

In order to get correct impression about action-based frameworks (in comparison with JSF) I want to be sure that I use them correctly (in a bigger or a lesser extent).

So, here I list some most-frequent tasks (at least for me) and describe how I solve them with JSF. I want to know how they should be solved with action-based framework (or separately with Spring MVC and Stripes if there is any difference for concrete task).

Rendering content: I can apply ready-to-use component from standard jsf libraries (core and html) or from 3rd-party libs (like RichFaces). I can combine 开发者_如何学编程simple components and I can easily create my own components which are based on standard components.
Rendering data (primitive or reference types) in the correct format: Each component allow to specify a converter for transforming data in both ways (to render and to send to the server). Converter is, as usual, a simple class with 2 small methods.
Site navigation: I specify a set of navigation-cases in faces-config.xml. Then I specify action-attribute of a link (or a button) which should match one or more of navigation cases. The best match is choosen by JSF.
Implementing flow (multiform wizards for example): I'm using JSF 1.2 so I use Apache Orchestra for the flow (conversation) scope.
Form processing: I have a pretty standard java-bean (backing bean in JSF terms) with some scope. I 'map' form fields on this bean properties. If everything goes well (no exceptions and validation is passed) then all these properties are set with values from the form fields. Then I can call one method (specified in button's action attribute) to execute some logic and return string which should much one of my navigation cases to go to the next screen.
Forms validation: I can create custom validator (or choose from existing) and add it to almost each component. 3rd-party libraries have sets of custom ajax-validators. Standard validators work only after page is submitted. Actually, I don't like how validation in JSF works. Too much magic there. Many standard components (or maybe all of them) have predefined validation and it's impossible to disable it (Maybe not always, but I met many problems with it).
Ajax support: many 3rd-party libraries (MyFaces, IceFaces, OpenFaces, AnotherPrefixFaces...) have strong ajax support and it works pretty well. Until you meet a problem. Too much magic there as well. It's very difficult to make it work if it doesn't work but you've done right as it's described in the manual.
User-friendly URLs: people say that there are some libraries for that exist. And it can be done with filters as well. But I've never tried. It seems too complex for the first look.

Thanks in advance for explaning how these items (or some of them) can be done with action-based framework.

I'll do my best to answer regarding Stripes. I've used Struts and JSF in the past, but not recently, so at best I have vague notions and feelings about them.

We are intimately familiar w/ Stripes, use it for most everything now, and really enjoy it. It is easy to jump into, supports many of the complicated scenarios, but you are also free to work OUTSIDE of it, which is really important when you want to build your own ajax widgets or talk to another system or something.

If you go the stripes route, I definitely recommend buying or download the book. It is a one stop shop for everything you need for Stripes, and is practically the only documentation for Stripersist (really nice feature, but NO web docs).

Rendering content: I can apply ready-to-use component from standard jsf libraries (core and html) or from 3rd-party libs (like RichFaces). I can combine simple components and I can easily create my own components which are based on standard components.

This is similar. Core, Html, Fmt, etc. as well as any custom tags you find, inc. display:tag, pack tag, and create your own. However, obviously you do not deal at the component level now, you deal with a tag that determines what is on the page / sent to or from the server.

Rendering data (primitive or reference types) in the correct format: Each component allow to specify a converter for transforming data in both ways (to render and to send to the server). Converter is, as usual, a simple class with 2 small methods.

Stripes has many built in converters, and it is easy to create custom converters for your more complex data types. Stripes supports very complex data structures to be mapped with little hassle. Combined with Stripersist, for example, I can put my model object directly on the ActionBean, put a few of the fields on the form, and Stripersist will hydrate the model from the db (based on its PK) and update that with the fields I put on the form - all before releasing control to me on the ActionBean.

Site navigation: I specify a set of navigation-cases in faces-config.xml. Then I specify action-attribute of a link (or a button) which should match one or more of navigation cases. The best match is choosen by JSF.

Navigation in stripes is based on what you name the ActionBeans, initially. There is no xml. Additionally, pretty urls are an annotation at the ActionBean level in Stripes 1.5, so you can do things like @UrlBinding("/{$event}/{model}") where /view/5 would take you to the "view" event handler for your Model object with the ID/PK of 5.

Implementing flow (multiform wizards for example): I'm using JSF 1.2 so I use Apache Orchestra for the flow (conversation) scope.

While I only am vaguely familiar with the concept of conversation scope, Stripes has Wizard Form functionality, but I haven't used it and am unable to really expand on that. I think it is a similar idea though.

Form processing: I have a pretty standard java-bean (backing bean in JSF terms) with some scope. I 'map' form fields on this bean properties. If everything goes well (no exceptions and validation is passed) then all these properties are set with values from the form fields. Then I can call one method (specified in button's action attribute) to execute some logic and return string which should much one of my navigation cases to go to the next screen.

Not drastically different. Instead of components on your [action] bean, you now have Java or custom types. ActionBeans are created per request and thrown away, unless you do something like put it in session, or wizard, or whatever. This is nice, because all the instance variables get mapped to the data from the form, you use it, then throw it away, and don't have to deal with any synchronization issues like struts did. After you do your thing with the data, Stripes lets you send a ForwardResolution (OK status), Redirect, or Streaming (JSON, file, etc). The Redirect-after-POST pattern is implemented nicely with the idea of flash scope (3/4 down the page).

Forms validation: I can create custom validator (or choose from existing) and add it to almost each component. 3rd-party libraries have sets of custom ajax-validators. Standard validators work only after page is submitted. Actually, I don't like how validation in JSF works. Too much magic there. Many standard components (or maybe all of them) have predefined validation and it's impossible to disable it (Maybe not always, but I met many problems with it).

Stripes allows validation in annotations on the instance variables on the ActionBean. They allow some defaults, required, maxlength, etc. or you can always create your own. The default is easy to add and flexible, while there is always the ability to make something completely customized.

Ajax support: many 3rd-party libraries (MyFaces, IceFaces, OpenFaces, AnotherPrefixFaces...) have strong ajax support and it works pretty well. Until you meet a problem. Too much magic there as well. It's very difficult to make it work if it doesn't work but you've done right as it's described in the manual.

This was my big problem with the JSF way of doing things. Even if you did get the widget right, you're still stuck with THAT widget. With Stripes, you can use whatever latest and greatest Jquery has to offer, and as long as you send the right GET or POST to the server, stripes knows what to do with it and can easily send JSON back. I think component frameworks fit a niche a few years ago much better when AJAX was hard, but JQ makes it so easy now.

User-friendly URLs: people say that there are some libraries for that exist. And it can be done with filters as well. But I've never tried. It seems too complex for the first look.

@UrlBinding, it's as easy as that.

My answer is not the one you want to hear: Don't switch from Component Framework to action framework

I switched the other way around after many years of action framework development and I'm never going back.

Of the 8 use cases you mentioned, only one comes to mind where Action frameworks are obviously better, and that is URL design / friendly URLs. It can be done in component frameworks as well, but much easier in Action Frameworks (especially in Stripes where you just annotate your ActionBean with the url).

I would advise you to try wicket, it is very easy to learn (much easier than JSF) and it let's you re-use many existing components as well.