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welcome-file-list... A BUG?  RSS feed

 
Ranch Hand
Posts: 48
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Hi, I can't understand why the welcome-file-list doesn't work.
web.xml (case 1 - IT DOES NOT WORK)
-------
When I try to access http://localhost, the
`Login` servlet is called. WHY??
-------
<!-- ... -->
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>abc.Login</servlet-class>
</servlet>
<servlet>
<servlet-name>Index</servlet-name>
<jsp-file>/index.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>Index</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- ... -->

web.xml (case 2 - IT WORKS FINE)
-------
The difference is the order of two
<servlet-mapping>
-------
<!-- ... -->
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>abc.Login</servlet-class>
</servlet>
<servlet>
<servlet-name>Index</servlet-name>
<jsp-file>/index.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Index</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<!-- ... -->
 
Greenhorn
Posts: 11
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Why do you want to use servlet mappings here? Servlet mappings only need to be used if you plan on mapping a URL extension to a mapping. For example, the Struts framework recognizes *.do as a servlet mapping so that all URLs that end with *.do filter through their servlet.
If you just want your app to default to index.jsp, your welcome-file-list alone should be enough to do the job.
 
Ranch Hand
Posts: 3695
IntelliJ IDE Java Ubuntu
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As for "why" does it happen?

You are mapping two different resources to the exact same URI ( '/' )

By demonstration, you've shown us that Tomcat resolves the impossible dilemma of two mappins for the same URI by ignoring every mapping except the last one it processes.

So in your first version, it calls the login servlet, because that's the last mapping, and in the second case it gets index.jsp. It *doesn't* get it from the welcome-file listing. By asking for / you are asking for a well-defined page (via your mappings). Welcome-list is used when the container doesn't know what to use.

p.s. Mapping *.jsp is unnecesary for just about every servlet container around.
 
It is sorta covered in the JavaRanch Style Guide.
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