Recipe1.4.Upgrading from Struts 1.1 to Struts 1.2

Recipe 1.4. Upgrading from Struts 1.1 to Struts 1.2

Problem

You want to upgrade an application based on Struts 1.1 to Struts 1.2.

Solution

1. Download the Struts 1.2 binary distribution from http://struts.apache.org/acquiring.html.

2. Copy the JAR files and Tag Library Descriptor (TLD) files from the Struts lib folder to your application's WEB-INF/lib folder.

3. If you use absolute URIs for the taglib directives in your JSP pages, change these to use the new URIs shown in Table 1-4.

Table 1-4. Struts 1.1 and 1.2 Taglib URIs

Struts 1.1 Taglib URI	Struts 1.2.4 Taglib URI
http://jakarta.apache.org/struts/tags-bean	http://struts.apache.org/tags-bean
http://jakarta.apache.org/struts/tags-html	http://struts.apache.org/tags-html
http://jakarta.apache.org/struts/tags-logic	http://struts.apache.org/tags-logic
http://jakarta.apache.org/struts/tags-template	http://struts.apache.org/tags-template
http://jakarta.apache.org/struts/tags-tiles	http://struts.apache.org/tags-tiles
http://jakarta.apache.org/struts/tags-nested	http://struts.apache.org/tags-nested

1. Change the DOCTYPE declaration at the beginning of your validation.xml file(s) to the following:

   <!DOCTYPE form-validation PUBLIC  "-//Apache Software Foundation//DTD Commons Validator Rules Configuration  1.1.3//EN" "http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd">

   
   

2. Change the DOCTYPE declaration at the beginning of your struts-config.xml file(s) to the following:

   <!DOCTYPE struts-config PUBLIC  "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN"  "http://struts.apache.org/dtds/struts-config_1_2.dtd">

   
   

3. Replace your use of the ActionError class with the ActionMessage class.

4. Replace your use of the ActionErrors class with the ActionMessages class except within the validate( ) method of any custom ActionForms.

5. Remove reliance on any init-param elements on the ActionServlet other than the config parameters. These parameters were deprecated in Struts 1.1 and are no longer supported in Struts 1.2. Instead, move these parameter values to your struts-config.xml file. Most of these parameters are replaced by attributes of the controller element.

6. Remove reliance on the name, scope, and type attributes of the html:form tag. These attributes were deprecated in Struts 1.1 and are no longer supported in Struts 1.2.

Discussion

The formal goal of Struts 1.2 was to remove deprecated methods and complete support for modules. Though Struts 1.2 doesn't make sweeping changes to the Struts core as Struts 1.1 did, it includes new features and enhancements that are worth the effort of upgrading. 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 8.4)

• Wildcard action mappings that allow you to reuse action elements for multiple related URLs (Recipe 7.8)

• New prebuilt actions including a new MappingDispatchAction class and a locale-switching LocaleAction (Recipes Section 6.10 and Section 12.4)

For a new application, you should use Struts 1.2. If you have an existing Struts 1.1 application, you will find that Struts 1.2 introduces a number of new and useful features. In comparison to migrating from Struts 1.0 to Struts 1.1, upgrading to Struts 1.2 is less intrusive and requires less code changes.

See Also

The Struts wiki has additional details on this upgrade. The relevant wiki page can be found at http://wiki.apache.org/struts/StrutsUpgradeNotes11to124.