Skip to main content

Struts2 - Working with Struts2 Action

First up, actions do the core work for  each request. They contain the business logic, hold the data and then select the result that should render the result page. Struts2 is an action-oriented Framework and actions are at its heart.

What does an action do?
Actions do three things. First, as you probably understand by now, an action's most important role, from the perspective of the framework's architecutre, is encapsulating the actual work to be done for a given request.
The second  major role is to serve as a data carrier in the framework's automatic transfer of data from the request to the view.
Finally, the action must assist the framework in determining which result should render the view that will be returned in the request response.

Whether you declare your action components with XML or Java annotations, when the framework creates your application's architecture, it'll organize your actions and other components into logical containers called packages. Many important operational attributes, such as the URL namespace to which actions will be mapped, are defined at the package level.  And, importantly, packages provide a mechanism for inheritance, which among other things allows you to inherit the components already defined by the framework.

Implementing actions
Implementing Struts 2 actions is easy. Basically, any class can be an action if it wants. It simply must provide an entry method for the framework to invoke when the action is executed. Struts2 Actions don't have to implment the Action interface. any object can informally honor the contract with the framework by simply implementing an execute() method that returns a control string.

The ActionSupport class
The ActionSupport class is a convenience class that provides default implementations of the Action Interface and several other useful interfaces, giving us such things as data validatoin and localization of error messages.  If your actions extends this class, they automatically gain the use of these implementations.


Popular posts from this blog

Stretch a row if data overflows in jasper reports

It is very common that some columns of the report need to stretch to show all the content in that column. But  if you just specify the property " stretch with overflow' to that column(we called text field in jasper report world) , it will just stretch that column and won't change other columns, so the row could be ridiculous. Haven't find the solution from internet yet. So I just review the properties in iReport one by one and find two useful properties(the bold highlighted in example below) which resolve the problems.   example:
<band height="20" splitType="Stretch"> <textField isStretchWithOverflow="true" pattern="" isBlankWhenNull="true"> <reportElement stretchType="RelativeToTallestObject" mode="Opaque" x="192" y="0" width="183" height="20"/> <box leftPadding="2"> <pen lineWidth="0.25"/> …

JasperReports - Configuration Reference

Live - solving the jasper report out of memory and high cpu usage problems

I still can not find the solution. So I summary all the things and tell my boss about it. If any one knows the solution, please let me know.

Symptom: 1.The JVM became Out of memory when creating big consumption report 2.Those JRTemplateElement-instances is still there occupied even if I logged out the system
Reason:         1. There is a large number of JRTemplateElement-instances cached in the memory 2.The clearobjects() method in ReportThread class has not been triggered when logging out
Action I tried:      About the Virtualizer: 1.Replacing the JRSwapFileVirtualizer with JRFileVirtualizer 2.Not use any FileVirtualizer for cache the report in the hard disk Result: The japserreport still creating the a large number of JRTemplateElement-instances in the memory     About the work around below,      I tried: item 3(in below work around list) – result: it helps to reduce  the size of the JRTemplateElement Object                Item 4,5 – result : it helps a lot to reduce the number of  JRTemplateE…