Professional Java Tools for Extreme Programming [Electronic resources]

Webdoclet Tags

Let's take a moment and discuss the tags we've used in our servlet example shown in the previous listing. The first tag in our example is @web.servlet. This tag is designed to create the class-level <servlet> element within the deployment descriptor. For our servlet, we've defined the name, display-name, and load-on-startup attribute of the tag:

@web.servlet name="SimpleServlet" 
display-name="Simple Servlet"  
1oad-on-startup=" Y'

The result of the tag once processed by XDoclet will be:

<servlet>
<servlet-name>SimpleServlet</servlet-name> 
<display-name>Simple Servlet</display-name> 
<servlet-class>example.SimpleServlet</servlet-class> 
<load-on-startup>1</load-on-start up>
</servlet>

The attributes available for the @web.servlet tag are shown in the following table.

The next two webdoclet tags in our example use the @web-servlet-init-param to create the init-param tags within the deployment descriptor:

@web-servlet-init-param name="table" value="production" 
@web-servlet-init-param name="account" value="accounts"

The result of these tags will be:

<servlet> 
<servlet-name>
...
<init-param>
<param-name>table</param-name> 
<param-value>production</param-value> 
</init-param>
<init-param>
<param-name>table</param-name> 
<param-value>production</param-value> 
</init-param>
</servlet>

The attributes available for the @web.servlet-init-param tag are shown in the following table.

After creating the necessary parameters for the servlet, we can define any J2EE resources needed by the servlet. In our example servlet, we will be accessing a database to pull rows that will be displayed to the user based on the init-params:

@web.resource-ref description="database connection" 
name=' jdbc/dbconnection" 
type="javax.sgl.DataSource" 
auth="Container"

The result of this webdoclet tag will be:

<resource-ref>
<description>JDBC Connection</description> 
<res-ref-name>jdbc/dbconnection</res-ref-name> 
<res-type>javax.sg1.DataSource</res-type> 
<res-auth>Container</res-auth>
</resource-ref>

The attributes available for the @web.resource-ref tag are shown in the following table.

Finally, we can apply the necessary pattern-matching mappings necessary for launching the servlet. This is accomplished using the @web.servlet-mapping tag:

@web.servlet-mapping url-pattern="/Example/*" 
@web.servlet-mapping url-pattern="/SimpleServlet"

These two tags will define the following mappings in our deployment descriptor:

<servlet-mapping>
<servlet-name>SimpleServlet</servlet-name> 
<url-pattern >/Example/* </url-pattern > 
</servlet-mapping>
<servlet-mapping>
<servlet-name>SimpleServlet</servlet-name> 
<url-pattern>SimpleServlet</url-pattem> 
</servlet-mapping>

The attribute available in the @web.servlet-mapping tag is shown in the following table.