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.

Attribute	Description	Required
Name	Servlet name	T
display-name	Servlet display name	F
Icon	Servlet icon	F
Description	Servlet description	F
load-on-startup	The load order of this servlet “ number where 1 is first	F
run-as	The role to run this servlet as	F

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.

Attribute	Description	Required
Name	Parameter value	T
Value	Parameter value	F
Icon	Servlet icon	F
Description	Servlet description	F

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.

Attribute	Description	Required
Name	Resource name	T
Type	Resource type	T
Auth	Resource authentication: Application or Container	T
Description	Resource description	F
Scope	Resource scope: Shareable Unshareable	F
Jndi-name	Resource Jndi-name	F

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.

Attribute	Description	Required
url-pattern	Pattern to match	T