wicket如何在页面之间传值

Question

如题，，，用pageparameters传值，好像传过去是StringValue，

Answer 1

Wicket学习：Modal Dialog的使用和参数传递

学习目标：掌握Modal Dialog的开发与控制，特别是主窗体与对话框之间的数据传递，包括主窗体如何判断用户按下的是对话框中的Ok还是Cancel还是Close按钮，以及输入参数和输出参数的传递。

Modal window: javascript modal window example  （0.5天，必学）

dialog对于开发有两大贡献：一是控制操作流程，dialog是一种非常出色的UI流程控制手段，特别是针对需要顺序执行的环节；二是方便了模块复用，Dialog本身通常就是一个可直接复用的基本模块。例如查询条件输入对话框、联系人选择对话框、打印预览对话框等。

wicket的dialog用到了AJAX技术，故这部分例子列在AJAX examples中。

- Example：Show modal dialog with a page 

- Example：Show modal dialog with panel

建议初学者重点掌握好上面两个例子。

注：基类选择WebPage还是Panel目前有何明显区别尚不很清楚。大家可以comment

 

参数传递

dialog使用中的难点是如何在调用方（通常是主窗体）和被调用方（即dialog）之间传递数据。下面的一些方法也适合在两个WebPage模块之间传递数据。以下假定模块A是主模块，模块B是对话框模块。

方法1：直接通过构造函数传递

如果仅仅需要从模块A向模块B传递数据，可在B中修改构造函数，并通过构造函数的参数传递。

对Wicket Page模块而言，似乎Page对象的构造函数是不可更改的（未尝试），但是如果基于Panel实现，构造函数中就是可以加入自己的参数的。

Reference

• How to use the same Form for editing and new，https://cwiki.apache.org/WICKET/how-to-use-the-same-form-for-editing-and-new.html（重）
• Wicket Ajax Confirmation Modal window，2010， http://www.mysticcoders.com/blog/wicket-ajax-confirmation-modal-window/ （good example，略显复杂） 

• Passing parameters to pages, https://cwiki.apache.org/WICKET/passing-parameters-to-pages.html (通过构造函数中的PageParameters对象和RequestCycle对象)
• Reusable multi step panel by using a delegate pattern, https://cwiki.apache.org/WICKET/reusable-multi-step-panel-by-using-a-delegate-pattern.html （重）

 

方法2：如果模块A需要获得模块B中的数据，则可重载模块B的onWindowClose()方法，并在该方法中访问模块B中与控件关联的各种model对象获取数据。但是由于该函数写在模块A中，违背了两个模块要尽可能独立的Hollywood原则，此方法不太好，但还算简单。

chooserWindow.setWindowClosedCallback(new ModalWindow.WindowClosedCallback() {

public void onClose(AjaxRequestTarget target) {

yourTextField.setModelObject(chooserPanel.getYourValue());

target.addComponent(yourTextField);

}

});

Reference

• Refreshing page when a modal window is closed, https://cwiki.apache.org/WICKET/modal-windows.html （该文提供了两种方法，分别是在主调方A和被调方B实现，但都不是太好）
• Pass form input from Modal Window back to the caller page, https://cwiki.apache.org/WICKET/pass-form-input-from-modal-window-back-to-the-caller-page.html

• Passing parameters to pages, https://cwiki.apache.org/WICKET/passing-parameters-to-pages.html (通过构造函数中的PageParameters对象和RequestCycle对象)

 

方法3：在方法2基础上，主模块提供一onOutputReady(...)方法，通过模块B的构造函数将onOutputReady函数传给B，由模块B在自己将要Close的时候调用之，在调用前由模块B将自己要返回给模块A的数据整理好，并通过该函数的输入参数调用之。这样模块A就可以通过函数参数直接拿到模块B的输出数据。但是在这种情况下，由于Java不直接支持函数指针，因此从语法形式上要通过接口interface或者delegate形式传递，也就是要把onOutputReady()封装到一个interface或一个小java类中传递。

例：

在主模块A中：

onMemberSelectOutputReady( param )

{

    更新显示

}

new UiMemberSelect( owner, input, onMemberSelectOutputReady())

或者更详细点，如下：

interface DialogModuleDataDelegate{

  onOutputReady( param );

};

在主模块A中：要implement DialogModuleDataDelegate且提供onOutputReady的具体实现。

在需要调用B的地方：new UiMemberSelect( owner, input, this )

这里，我们假定主模块A本身就实现了DialogModuleDataDelegate接口，这样只要在new UiMemberSelect中传递this即可。（这样做的小缺点是如果主模块A需要同时调用多个dialog，实现多个dialog对应的onOutputReady会造成命名冲突，需要在语法上规避）。

这种写法改进了方法2。因此，以后就不要再采用方法2了。

参考：

• Reusable multi step panel by using a delegate pattern, https://cwiki.apache.org/WICKET/reusable-multi-step-panel-by-using-a-delegate-pattern.html　（重）
• Function Pointer in Java，http://stackoverflow.com/questions/1163367/function-pointer-in-java?rq=1
• Wicket Ajax Confirmation Modal window，2010， http://www.mysticcoders.com/blog/wicket-ajax-confirmation-modal-window/ （good example，略显复杂）

 

方法4：虚函数法

在dialog模块中设计一个onDataReady()虚函数，在数据准备好（如用户按ok和cancel按钮的时候负责整理数据并且调用之），但是该虚函数的真正实现由模块A在调用的时候实现。

被调用的模块B：

virtual onDataReady(modalresult, params)

在主模块A中：

new UiMemberSelect(){

onDataReady(modalresult, params){

switch (modalresult){

case OK:

case CANCEL:

}

}

}

这样进一步简化了语法形式，且面对多个dialog和多种data ready的情况，也可方便处理。推荐采用。

Reference

• Wicket: how to write a reusable modal window popup，2008，http://stuq.nl/weblog/2008-06-05/wicket-how-to-write-a-reusable-modal-window-popup (good！)
• How to send a Java object to the ModalWindow，2010，http://apache-wicket.1842946.n4.nabble.com/How-to-send-a-Java-object-to-the-ModalWindow-td2312589.html
• Wicket Ajax Confirmation Modal window，2010， http://www.mysticcoders.com/blog/wicket-ajax-confirmation-modal-window/ （good example，略显复杂）

 

方法5：使用URL参数 

Wicket已经提供了PageParameters对象，可以考虑如下形式：

PageParameters pars = new PageParameters();

pars.add("id", 12345);

setResponsePage(MyPage.class, pars);

 

Reference：

• Wicket redirect: how to pass on parameters and keeps URLs “pretty”? 2010，http://stackoverflow.com/questions/4155591/wicket-redirect-how-to-pass-on-parameters-and-keeps-urls-pretty
• How to reference a page with parameters Wicket，http://stackoverflow.com/questions/7516705/how-to-reference-a-page-with-parameters-wicket?rq=1
• Passing info message to a Wicket page while using PageParameters，http://stackoverflow.com/questions/10189570/passing-info-message-to-a-wicket-page-while-using-pageparameters?rq=1 （该文提到：You can't use both PageParameters and another parameter as constructor arguments, because Wicket can't create your page instance with such a constructor when the page is requested. Wicket only knows how to instantiate pages with default constructors or pages with a PageParameters parameter.）
• Getting parameters from another class in Java，2012，http://stackoverflow.com/questions/12806638/getting-parameters-from-another-class-in-java?rq=1

 

方法6：利用Session来传递数据

Session相当于是个全局数据缓冲区。这种方法使用方便，但是能不用就不用

 

方法7：Wicket 1.5 offers a simple, yet flexible, way for component to communicate with each other in a decoupled manner. （IEventSource和IEventSink接口）

Reference

• Wicket 1.5 offers a simple, yet flexible, way for component to communicate with each other in a decoupled manner. （IEventSource和IEventSink接口），https://cwiki.apache.org/WICKET/migration-to-wicket-15.html#MigrationtoWicket1.5-Intercomponentevents
• calling a child page component from parent page component in wicket，2011，http://stackoverflow.com/questions/7595976/calling-a-child-page-component-from-parent-page-component-in-wicket?rq=1

Reference

[参数传递问题]

How to send a Java object to the ModalWindow，

http://apache-wicket.1842946.n4.nabble.com/How-to-send-a-Java-object-to-the-ModalWindow-td2312589.html

Q: Pass form input from modal window back to the caller page

http://apache-wicket.1842946.n4.nabble.com/Pass-form-input-from-modal-window-back-to-the-caller-page-td1855573.html

Wicket redirect: how to pass on parameters and keeps URLs “pretty”?, 2010

http://stackoverflow.com/questions/4155591/wicket-redirect-how-to-pass-on-parameters-and-keeps-urls-pretty

Modal Windows, https://cwiki.apache.org/WICKET/modal-windows.html

(推荐采用setWindowClosedCallback方法以方便实现调用方和被调用方的解耦)

 

Reference 

Modal Windows, https://cwiki.apache.org/WICKET/modal-windows.html

JQuery UI Dialog as Wicket behavior example

http://code.google.com/p/jqwicket/wiki/DialogExample（仅用于理解dialog背后的实现机制）

 

如何改变Wicket modal window/dialog的外观－－用CSS，下文给出了代码

Can the Wicket modal window be customized?

http://stackoverflow.com/questions/1385314/can-the-wicket-modal-window-be-customized

 

下文给出了modal window/dialog的一种规范写法，实现调用方和被调用方相对较松的解耦。建议初学者使用。

Wicket: how to write a reusable modal window popup，2008

http://stuq.nl/weblog/2008-06-05/wicket-how-to-write-a-reusable-modal-window-popup

(with source code)

 

 

Wicket Ajax Confirmation Modal window, 2008,

http://www.mysticcoders.com/blog/wicket-ajax-confirmation-modal-window/

该文给出了YES,NO两个按钮的实现方法。不过，应该用Ok, Cancel或YES/NO/Cancel更好些。

 

Close wicket modal window by pressing a button, 2011,

http://stackoverflow.com/questions/4944728/close-wicket-modal-window-by-pressing-a-button

在modal window中嵌入了视频

 

Q: Passing info to the modal window，2011,

http://markmail.org/message/ec5rf4oe6djgbb2q

R: I often pass the 'real' or 'domain' model object that a form is editing as a parameter to the form/modal constructor and then store a IModel wicket model wrapper object around that model object in the form/modal.

利用构造函数的参数来传递数据对象。

 

 

Ｑ：Download file from ModalWindow problem

http://apache-wicket.1842946.n4.nabble.com/Download-file-from-ModalWindow-problem-td4169964.html

 

 

 

Ｑ：

Subject: Re: modal window before submitting ajax-less form

Makes sense. In that case, Sven, how can I have a modal window rendered

before hand so I can hide/show as needed, something like an ajax-less modal?

I wouldn't like to duplicate the effort of rendering a modal window myself.

Any idea?

R: View this message in context: 

http://apache-wicket.1842946.n4.nabble.com/modal-window-before-submitting-ajax-less-form-tp4653108p4653128.html

Sent from the Users forum mailing list archive at Nabble.com.

 

Q：I Want to implement a confirmation box with ok and cancel button that will appear on page load if it satisfies some conditions. 

and if user clicks on Ok/Cancel button it should perform an operation.

Please suggest me

http://www.linkedin.com/groups/Confirmation-Box-80181.S.55805285

 

 

 How to Wicket Redirect with large parameters? 2012， http://stackoverflow.com/questions/13853320/how-to-wicket-redirect-with-large-parameters?rq=1 （If you don't have any other choice, I think you can try to do what you want through Javascript, asynchronously loading the webpage with this huge page parameter (via AjaxRequestTarget.appendJavaScript) and displaying the result in your modal window. ）