Struts Guidelines

Struts (or more correctly, the Struts Action Framework) is probably the most successful Java web-application framework to date. It enables organization of Java web-applications using a model-view-controller (MVC) approach that makes it easier to write and maintain non-trivial applications.

The framework comprises

  • A front controller servlet (ActionServlet) that accepts, processes, and routes all incoming HTTP requests in accordance with a configuration file (struts-config.xml)

  • RequestProcessor and Action classes that can be extended and customized with application logic.

  • A set of JSP tag libraries (html, bean, logic, tiles) to simplify building forms and displaying output.

  • Support for populating HTML form input into regular or dynamic beans (DynaBeans).

  • Support for validating input and displaying error messages (ActionErrors, ApplicationResources.properties)

The version of Struts shipped with JDeveloper 10.1.2 was 1.1. A number of books have been written about this version, see the Apache Struts 1.1 Project Home Page. Using 1.2 should not be a significant problem, but it does not include compelling enhancements. Note Struts 1.1 includes Commons BeanUtils 1.6.

JSPs

  • Organize applications into pages, eg. CustomerSearch.jsp, CustomerView.jsp, CustomerEdit.jsp.

  • Follow the Oracle Browser Look And Feel (BLAF) guidelines for all corporate applications, see the Oracle Browser Look and Feel (BLAF) Guidelines. Use the blaf.css provided with JDeveloper, do not modify it.  Use the icons from the BLAF icon repository.

  • Place all JSPs into the WEB-INF directory, where they cannot be invoked directly. Provide a start.jsp in the public web root directory that forwards to a Struts action to start the application. Set start.jsp as the welcome file in web.xml.

  • Refrain from adding scriplets to JSPs as far as possible: place code in the corresponding Java class and use Struts :bean tags to display results in the JSP.

Action Classes

  • For each JSP create a corresponding Java class that extends DispatchAction and which handles requests from the JSP.

  • Use DynaActionForms to capture form input. These are configured in struts-config.xml, eliminating the need to write Java bean classes for each input form.

  • Validate all input on the server side. Although JavaScript can be used on the client for added responsiveness, client side validation can always be bypassed or disabled.

  • Do not place database access code into JSPs or Action classes: factor out this code into separate data access objects (DAOs). Configure data sources using the servlet container, not the (deprecated) struts-config.xml option. Name data sources after the username or schema used for the connection, not the target database instance.

Error Handling

  • Write error diagnostic and tracing information to the servlet context log, do not simply print a stack trace.  This may be done by extending struts.action.RequestProcessor.

  • Declare error pages in web.xml to handle unexpected server errors (500) and missing resources (404).  It may be convenient to comment these out in development environments.

  • Review Ambysoft’s Coding Standards for Java

  • At a minimum use an initial capital for classes and an initial lower case for variables. Use all caps only for constants, ie. where ‘static final’ is used.

  • Do not declare global variables: at a minimum use singleton beans. Global constants are OK.

References

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