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Struts 2 Interceptors

Struts 2 Interceptors. By, Srinivas Reddy.S. www.JAVA9S.com. Interceptors. Separates the cross cutting concerns Pre Processing and Post processing. Manages the work flow. www.JAVA9S.com. www.JAVA9S.com. Interceptor By Example. A Login page.

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Struts 2 Interceptors

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  1. Struts 2 Interceptors By, SrinivasReddy.S www.JAVA9S.com

  2. Interceptors • Separates the cross cutting concerns • Pre Processing and Post processing. • Manages the work flow. www.JAVA9S.com

  3. www.JAVA9S.com

  4. Interceptor By Example • A Login page • A Successful login page with a link to authorized page www.JAVA9S.com

  5. Interceptor by Example • Redisplay the login page for wrong credentials • Access the Authorized page directly with out logging should forward the login page www.JAVA9S.com

  6. Creating an Interceptor • The interceptor class should implement the Interceptor interface. • Implement the intercept method. • Do the pre processing and if everything is ok, invoke the invocation.invoke() which will call the next component in queue. • If something goes wrong, return a string based on which a result page will be picked and sent to the client. • After the invocation.invoke(), write the post processing logic

  7. Important Interceptors in defaultStack • servletConfig • Sets the context related objects like HttpServletRequest, HttpServletResponse, HttpSession and HttpServletContext to the action if the action class implements the ServletRequestAware, ServletResponseAware, SessionAware, ServletContextAware respectively

  8. Important Interceptors in defaultStack • modelDriven • Sets the form bean declared by the action in the valuestack. • The action should implement the ModelDriven interface.

  9. Important Interceptors in defaultStack • staticParams Helps to set the values from the struts.xml to the properties of action instead of the request parameters. • params Responsible for all the request parameters to be set to the properties of the action. • conversionError Tries to covert the request parameters to primitive data types and if there are any errors, the field errors will be set.

  10. Important Interceptors in defaultStack • Validation Checks if the validationAware is implemented by action or validates by the validation framework and sets the validation errors. • workflow Checks if there are any field errors or action errors and then decides to invoke the action or to re send the input page

  11. Interceptors in defaultstack <interceptor-stack name="defaultStack"> <interceptor-ref name="exception"/> Handles the result based on the exception. <interceptor-ref name="alias"/> Enables to have a different named parameter <interceptor-ref name="servletConfig"/> Will set the request, response, session objects to the action class. <interceptor-ref name="prepare"/> This interceptor calls prepare() on actions which implement Preperable <interceptor-ref name="i18n"/>sets the locale specified in a session as the locale for the current action request <interceptor-ref name="chain"/> Helps to chain the actions. <interceptor-ref name="debugging"/>Provides several different debugging screens to provide insight into the data behind the page <interceptor-ref name="profiling"/>Allows profiling to be enabled or disabled via request parameters, when devMode is enabled. www.JAVA9S.com

  12. Interceptors in defaultstack <interceptor-ref name="scopedModelDriven"/>An interceptor that enables scoped model-driven actions. <interceptor-ref name="modelDriven"/>Watches for ModelDriven actions and adds the action's model on to the value stack <interceptor-ref name="fileUpload"/>Helps in file upload. <interceptor-ref name="checkbox"/>Looks for a hidden identification field that specifies the original value of the checkbox. <interceptor-ref name="staticParams"/>This interceptor populates the action with the static parameters defined in the action configuration. <interceptor-ref name="params">This interceptor sets all parameters on the value stack <param name="excludeParams">dojo\..*</param> </interceptor-ref> www.JAVA9S.com

  13. Interceptors in defaultstack <interceptor-ref name="conversionError"/>ConversionErrorInterceptor adds conversion errors from the ActionContext to the Action's field errors. <interceptor-ref name="validation">Validates the parameters <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> <interceptor-ref name="workflow"> An interceptor that does some basic validation workflow before allowing the interceptor chain to continue <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> </interceptor-stack> www.JAVA9S.com

  14. Thank you Download PPT and example code from http://java9s.com

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