Reusing Validator Attribute Values 8. Validating Using Regular Expressions 8. Validating Dependent Fields in Struts 1. Validating an Indexed Property 8. Validating Dates 8. Validating Field Equality with a Custom Validator 8. Validating Field Equality in Struts 1. Validating Two or More Choices 8. Adding a Custom Validation to a Validator Form 8. Validating a Wizard Form 8. Localizing Validation Rules 9.
Exception and Error Handling Introduction 9. Simplifying Exception Processing in an Action 9. Custom Processing for Declared Exceptions 9. Using Exception Error Codes 9. Using a Global Error Page 9. Reporting Errors and Messages from an Action 9. Formatting Error Messages Connecting to the Data Introduction Displaying Relational Data Integrating Struts with Hibernate Decoupling Your Application from External Services Integrating Spring with Struts Refreshing Application Data Security Introduction Securing Actions Using a Base Action Securing a JSP Page Restricting Actions by Role Allowing a User to Log in Automatically Letting the Container Manage Security Limiting the Size of Uploaded Files Internationalization Introduction Detecting Browser Language Settings Using an Application-Wide Locale Changing Locale on the Fly Creating Localized Messages from an Action Displaying Locale-Specific Text Displaying Locale-Specific Images Supporting Character Sets Localizing Look and Feel Testing and Debugging Introduction Deploying an Application Automatically Configuring Struts Logging Adding Logging to Your Own Classes Enabling Remote Debugging Troubleshooting JSP Pages Testing Your Actions with Mock Objects Testing Your Actions in the Container Testing Application Functionality Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are as essential for the working of basic functionalities of the website.
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A framework layer that supports integration between Struts application and Java Server Faces technology. Once you have downloaded the source and binary distributions, you will want to deploy the example applications included with Struts, as described in Recipe 1.
Recipe 1. This recipe assumes that you are using Tomcat 5. If you are using Struts 1. On Windows, you will see Tomcat startup in a separate terminal window. The output in this terminal window displays information about the applications deployed and the state of Tomcat:. You can use this output to verify that the application deployed and that Tomcat successfully started and is running.
In the output shown above, you can see that Tomcat deployed the struts-example. In addition, the last line indicates that Tomcat is running and the length of time it took to start up. Tomcat starts up as a background process. You can monitor the output from Tomcat using the following:. Other than the different operating system file paths, the output will be identical to the output on Windows shown previously.
You should see the page shown in Figure Using and examining the struts-example web application is an excellent learning aid for Struts. Before you write your first Struts application, you should understand how the struts-example application works. The best way to do this is to deploy the application. Experiment with the interface and take the walking tour. You will want to follow along in the walking tour by using your text editor or IDE to view the source code.
You will need to download the Struts binary and source distributions to deploy the struts-example. The WAR files are included in the binary distribution. The source code is supplied in the source distribution. In addition to the struts-example application, additional web applications demonstrate other Struts features as shown in Table The seminal Struts Mail Reader example. Demonstrates most of the basic core features and functions provided by Struts. Struts 1. Table lists the web applications contained in the Struts 1.
Replaces the struts-exercise-taglib. Combines the tag library, upload, and Validator examples into one application. Replace the Struts 1.
Recompile your application using the new libraries and address any compilation errors. While Struts 1. You will need to change your use of the tag library URIs, as they have changed in Struts 1. Table shows the changes to the tab library URIs. The most significant changes in Struts 1.
ActionServlet and the Struts Action class org. RequestProcessor as well. The ActionServlet delegates request handling to the request processor. With Struts 1. If a Struts 1. If ActionServlet was subclassed, you should extend the RequestProcessor instead. The other primary enhancement, as mentioned, is in the Struts Action.
Example shows a simple Action that implements the perform method. Example is the same Action using Struts 1. As you can see, with the Struts 1. If you are migrating directly from Struts 1. Though it will continue to function as is, I recommend convert your code to use the execute method as soon as you can. Doing so will reduce the work to convert to Struts 1. More significantly, it will allow to you take advantage of the Struts 1.
Recipe 9. Download the Struts 1. Replace your use of the ActionError class with the ActionMessage class. Replace your use of the ActionErrors class with the ActionMessages class except within the validate method of any custom ActionForm s.
Remove reliance on any init-param elements on the ActionServlet other than the config parameters. These parameters were deprecated in Struts 1. Instead, move these parameter values to your struts-config. Most of these parameters are replaced by attributes of the controller element.
Remove reliance on the name , scope , and type attributes of the html:form tag. These attributes were deprecated in Struts 1. The formal goal of Struts 1. Though Struts 1. Many of these features are discussed throughout this book. Here are some of the most significant enhancements:. New validwhen Validator rule for complex cross-field validations Recipe 8.
Wildcard action mappings that allow you to reuse action elements for multiple related URLs Recipe 7. For a new application, you should use Struts 1. If you have an existing Struts 1. In comparison to migrating from Struts 1. The Struts wiki has additional details on this upgrade. Take a refactoring-style approach by applying Struts as you add new features to your application. As you increase your Struts knowledge, you can re-architect the existing code to use Struts.
If no new development is planned for the application, refactor the existing JSPs a page at a time. The level of difficulty to migrate an existing JSP application depends greatly on the complexity and architectural soundness of the application.
If the application uses a Model 1 architecture—that is, all logic is contained in the JSP page—it could be quite a challenge. You may find that you need to redesign the application from scratch to separate out the business logic from the presentation before you begin.
If you are new to Struts, then learn Struts on development of a new application instead of attempting to retrofit Struts to an application well into development. However, some projects have altered their architectural underpinnings in midstream. If you are in this situation, steer the project plan so Struts is applied to new development first and preferably to features not on the critical path. Once you increase your Struts knowledge, it will be easier to convert existing code.
To make this more concrete, consider a simple example consisting of three JSP pages. The first page is the main welcome page that displays a link to the second page. The second page displays two form input fields.
When the user submits the form, the result of adding the values is displayed on the third JSP page. First, Example shows the index. The page in Example submits the form to a JSP page for displaying results. This target page shown in Example utilizes a JavaBean to hold the values received in the request from the form. The values are outputted using request-time expressions, and the sum is calculated using a scriptlet. Finally, this calculated sum is displayed. This application demonstrates some of the more undesirable approaches to using JSP.
While the use of the JavaBean is laudable, the calculation is performed within the JSP using scriptlet. This results in a mixing of business logic with presentation, and scriptlets embedded Java code can lead to maintainability problems for JSP applications.
Formulating a strategy for converting this application to Struts is simple. Though this example may be trivial, the strategy followed will be applicable to more complex applications.
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