11.4 Creating Your Own Validation Rules (Web hosting ecommerce) The Validator
11.4 Creating Your Own Validation Rules The Validator framework is preconfigured with many of the most common rules that you’re likely to need for your Struts applications. If your application has validation requirements that are not met by the default rules, you have complete freedom to create your own. There are several steps that you must follow, however, to create your own customized rules: 1. Create a Java class that contains the validation methods. 2. Edit the validation-rules.xml file or create your own version. If you do create a new validation resource file, be sure to add it to the list of resource files in the Validator plug-in. 3. Use the new validation rules in the validation.xml file for your application. Each validation method you create must have the following signature: public static boolean validateXXX( java.lang.Object, org.apache.commons.validator.ValidatorAction, org.apache.commons.validator.Field, org.apache.struts.action.ActionErrors, javax.servlet.http.HttpServletRequest, javax.servlet.ServletContext ); where validateXXX can be whatever you want it to be, as long as it’s not a duplicate rule name. Table 11-3 explains the arguments to the validateXXX( ) method. Table 11-3. The validateXXX( ) method arguments Parameter Description Object The JavaBean on which validation is being performed ValidatorAction The current ValidatorAction being performed Field The field object being validated ActionErrors The errors objects to add an ActionError to if the validation fails HttpServletRequest The current request object ServletContext The application’s ServletContext In most cases, the method should be static. However, you can define instance-level methods as well. Regardless of whether your methods are static, you must ensure that they are thread-safe. Example 113 illustrates a new validation rule that validates whether a String value is a valid boolean. Example 11-3. A validation rule that validates a boolean value import java.io.Serializable; import java.util.Locale; import javax.servlet.ServletContext;
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