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| <document> |
| <properties> |
| <title>Determining the Page Class</title> |
| </properties> |
| <body> |
| |
| <section name="Determining the Page Class"> |
| <p> |
| When it comes time for Tapestry to instantiate a page, it must identify the Java |
| class to instantiate. |
| </p> |
| |
| <p> |
| Tapestry pages implement the |
| <a href="../apidocs/org/apache/tapestry/IPage.html">IPage</a> |
| interface. Because this is a large interface, you will typically extends the |
| <a href="../apidocs/org/apache/tapestry/html/BasePage.html"> |
| BasePage |
| </a> |
| base class (for HTML pages). |
| </p> |
| |
| <p> |
| Typically, you will identify the page class within the page's specification, using |
| the |
| <a href="spec.html#spec.page-specification"><page-specification></a> |
| element's class attribute. |
| </p> |
| |
| <p> |
| In many cases, however, the page specification is optional. Alternately, the class |
| attribute may be omitted from the page specification. Tapestry takes the following |
| steps to find the class for a page: |
| </p> |
| |
| <ul> |
| <li>As indicated in the page specification</li> |
| <li> |
| By searching the packages listed in the application specification (more below) |
| </li> |
| <li> |
| The application specification's org.apache.tapestry.default-page-class property |
| </li> |
| <li>The global property org.apache.tapestry.default-page-class</li> |
| </ul> |
| |
| <p> |
| The most useful of these is the second option, to search. For this step, Tapestry |
| looks in the application specification for the |
| org.apache.tapestry.page-class-packages |
| <a href="spec.html#spec.meta"><meta></a> |
| property. This is a comma-seperated list of package names to search. The list of |
| packages is optional, and the default Java package is searched last. |
| </p> |
| |
| <p> |
| Also, for this search, the page name is converted into a partial class name. For |
| pages inside folders, the folder names are part of the package name, so page name |
| <code>admin/EditUser</code> |
| will be become |
| <code>admin.EditUser</code> |
| . |
| </p> |
| |
| <p> |
| So, if the prefix list is |
| <code>org.example.pages</code> |
| , then Tapestry will search for |
| <code>org.example.pages.admin.EditUser</code> |
| , then |
| <code>admin.EditUser</code> |
| (that is, in the default package). |
| </p> |
| |
| <p> |
| Only if those searches fail to locate a class does Tapestry continue to the next |
| steps, using default page class names in the application specification and beyond. |
| </p> |
| |
| <span class="info"> |
| <strong>Note:</strong> |
| <p> |
| These steps are specified in the |
| <a |
| href="../tapestry-framework/hivedoc/config/tapestry.page.PageClassProviderChain.html"> |
| tapestry.page.PageClassProviderChain |
| </a> |
| configuration point. |
| </p> |
| </span> |
| |
| <p> |
| For simplicity, we described the search for application pages. For pages within a |
| library, the process is the same, but it is the library's specification which is |
| searched for the list of packages, and later, for the default page class name. |
| </p> |
| |
| <subsection name="Component Classes"> |
| |
| |
| <p> |
| A similar search occurs for components (again, with the express desire that the |
| class attribute of the |
| <a href="spec.html#spec.component-specification"> |
| <component-specification> |
| </a> |
| <em>not</em> |
| be used). |
| </p> |
| |
| <ul> |
| <li>As defined by the component specification</li> |
| <li> |
| In any package defined by the containing namespace's |
| org.apache.tapestry.component-class-packages meta data property (if any) |
| </li> |
| <li>In the default package</li> |
| <li> |
| <a |
| href="../apidocs/org/apache/tapestry/BaseComponent.html"> |
| BaseComponent |
| </a> |
| is the final default |
| </li> |
| </ul> |
| |
| <span class="info"> |
| <strong>Note:</strong> |
| <p> |
| These steps are specified in the |
| <a |
| href="../tapestry-framework/hivedoc/config/tapestry.page.ComponentClassProviderChain.html"> |
| tapestry.page.ComponentClassProviderChain |
| </a> |
| configuration point. |
| </p> |
| </span> |
| </subsection> |
| |
| </section> |
| |
| </body> |
| </document> |
