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From Robin Curts <rcu...@robincurts.com>
Subject Re: Issue getting Context inside a servlet
Date Wed, 13 Oct 2004 14:07:28 GMT
great suggestion.  that's what i needed.  Cheers!

Shapira, Yoav wrote:

>Hi,
>To read a resource (file, serialized, doesn't matter), use either
>ServletContext#getResource or Class#getResource (or the
>getResourceAsStream equivalents).  The former will get anything under
>your docBase, including in WEB-INF.  The latter will get anything on
>your classpath, including in WEB-INF/classes and WEB-INF/lib (but not
>just WEB-INF, for example).
>
>So if a properties file is at /WEB-INF/myFile.prop, you'd use something
>like:
>Properties myProps = new Properties();
>myProps.load(getServletContext().getResourceAsStream("/WEB-INF/myFile.pr
>op"));
>
>To read a serialized file from /WEB-INF/myData.ser, you'd use something
>like
>Object myObj = new
>ObjectInputStream(getServletContext().getResourceAsStream("/WEB-INF/myDa
>ta.ser")).readObject();
>
>I abbreviate my examples to make them neat for this message.  You might
>want to break them out into multiple lines and add null checks, e.g. if
>myFile.prop or myData.ser are not there, the getResourceAsStream call
>will return null.
>
>These approaches are safe, portable, efficient, and clean.
>
>Yoav Shapira http://www.yoavshapira.com
> 
>
>  
>
>>-----Original Message-----
>>From: Robin Curts [mailto:rcurts@robincurts.com]
>>Sent: Wednesday, October 13, 2004 9:56 AM
>>To: Tomcat Users List
>>Subject: Re: Issue getting Context inside a servlet
>>
>>Well I have some files that I want to have available to the web
>>application (properties file, some serialized objects).  My first
>>attempt was to add -Dhomedir=/path/to/some/directory when I started
>>tomcat -- but that doesn't seem correct.  So then I wanted to get the
>>path to the WEB-INF directory and put everything into there.  Neither
>>solution seems all that great, and if you have any suggestions I'm all
>>ears.
>>
>>By the way -- the getServletContext().getRealPath("/") was fantastic.
>>Thanks for that tip.
>>
>>
>>
>>Shapira, Yoav wrote:
>>
>>    
>>
>>>Hi,
>>>Why are you even going down this route?  Any solution you end up with
>>>will be tied to Tomcat and not portable at all.  There's also no
>>>guarantee we'll keep these internal APIs consistent or available to
>>>      
>>>
>your
>  
>
>>>webapp in future Tomcat versions.
>>>
>>>If you do want to keep going down this path, you probably need to mark
>>>your context as privileged, like the manager webapp does (see its
>>>context.xml file for an example).
>>>
>>>The hack to get the DocBase getServletContext().getRealPath("/").
>>>      
>>>
>That
>  
>
>>>works for unpacked WARs but not packed WARs, where
>>>      
>>>
>getRealPath(anything)
>  
>
>>>returns null.  If you need the "docBase" simply as a URL, you can
>>>      
>>>
>always
>  
>
>>>do getServletContext().getResource("/") which will work in packed and
>>>unpacked webapp deployments.
>>>
>>>If you elaborate a bit on why you need the docbase, we might be able
>>>      
>>>
>to
>  
>
>>>come up with better alternative approaches for you.
>>>
>>>Don't make your solution container-specific unless you really have to.
>>>Stick to the letter and the spirit of the Servlet Spec, and you'll end
>>>up with a portable webapp.
>>>
>>>Yoav Shapira http://www.yoavshapira.com
>>>
>>>
>>>
>>>
>>>      
>>>
>>>>-----Original Message-----
>>>>From: Robin Curts [mailto:rcurts@robincurts.com]
>>>>Sent: Wednesday, October 13, 2004 9:26 AM
>>>>To: tomcat-user@jakarta.apache.org
>>>>Subject: Issue getting Context inside a servlet
>>>>
>>>>What I am trying to accomplish:
>>>>I'm trying to build a servlet that I can get the DocBase with, so I'm
>>>>trying to locate org.apache.catalina.Context from the servlet.
>>>>
>>>>Tomcat Version: 5.0.28
>>>>Java Version: 1.4.2_05
>>>>
>>>>What I'm doing:
>>>>I am implementing ContainerServlet and this works great when I run
>>>>        
>>>>
>the
>  
>
>>>>servlet through a web application defined in
>>>>$catalina.home/servers/webapps/<my_webapp>.  Pretty much in the same
>>>>place as the manager servlet.  However when I run it as an installed
>>>>
>>>>
>>>>        
>>>>
>>>WAR
>>>
>>>
>>>      
>>>
>>>>file I am getting a nasty null pointer exception (running from
>>>>$catalina.home/webapps/<my_webapp>).
>>>>
>>>>The issue:
>>>>setWrapper() is never getting called when I have this inside the
>>>>$catalina.home/webapps/ directory tree... only when I have it in
>>>>$catalina.home/server/ directory tree.  Any thoughts on this?  When
>>>>
>>>>
>>>>        
>>>>
>>>this
>>>
>>>
>>>      
>>>
>>>>webapp goes live it will be installed as a WAR file and I won't be
>>>>        
>>>>
>able
>  
>
>>>>to control what directory it is in.  Any thoughts?
>>>>
>>>>Here is my servlet, pretty basic, just trying to find the Context and
>>>>DocBase:
>>>>//-- SERVLET START --
>>>>import org.apache.catalina.*;
>>>>import javax.servlet.http.*;
>>>>import javax.servlet.*;
>>>>import java.util.*;
>>>>import java.io.*;
>>>>
>>>>public class Ctx extends HttpServlet implements ContainerServlet {
>>>>
>>>>  Context context;
>>>>  Deployer deployer;
>>>>  Wrapper wrapper;
>>>>
>>>>  public Ctx() {
>>>>      context = null;
>>>>      deployer = null;
>>>>      wrapper = null;
>>>>  }
>>>>
>>>>  public Wrapper getWrapper() {
>>>>      return wrapper;
>>>>  }
>>>>
>>>>  public void setWrapper(Wrapper wrapper) {
>>>>      this.wrapper = wrapper;
>>>>      try {
>>>>          context = (Context)wrapper.getParent();
>>>>          deployer = (Deployer)context.getParent();
>>>>      } catch (NullPointerException e) {
>>>>          context = null;
>>>>          deployer = null;
>>>>      }
>>>>  }
>>>>
>>>>  public void destroy() {
>>>>      // do nothing
>>>>  }
>>>>
>>>>  public void init() {
>>>>      // do nothing
>>>>  }
>>>>
>>>>  public void doPost(HttpServletRequest request, HttpServletResponse
>>>>response)
>>>>  throws IOException, ServletException {
>>>>      doGet(request, response);
>>>>  }
>>>>  public void doGet(HttpServletRequest request, HttpServletResponse
>>>>response)
>>>>  throws IOException, ServletException {
>>>>      PrintWriter out = response.getWriter();
>>>>      response.setContentType("text/plain");
>>>>      out.println("My Context Object: " + context);
>>>>      out.println("Doc Base: " + context.getDocBase());
>>>>      out.flush();
>>>>      out.close();
>>>>  }
>>>>}
>>>>//-- SERVLET END --
>>>>
>>>>
>>>>--
>>>>/**
>>>>* Robin Curts
>>>>* rcurts@robincurts.com
>>>>* http://www.robincurts.com
>>>>* (813) 786-8634
>>>>*/
>>>>
>>>>
>>>>---------------------------------------------------------------------
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>>>>
>>>>
>>>>        
>>>>
>>>
>>>
>>>This e-mail, including any attachments, is a confidential business
>>>      
>>>
>>communication, and may contain information that is confidential,
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>>
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>  
>
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>>
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>>    
>>
>>>---------------------------------------------------------------------
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>>>
>>>
>>>      
>>>
>>--
>>/**
>>* Robin Curts
>>* rcurts@robincurts.com
>>* http://www.robincurts.com
>>* (813) 786-8634
>>*/
>>
>>
>>---------------------------------------------------------------------
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>>    
>>
>
>
>
>
>This e-mail, including any attachments, is a confidential business communication, and
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is intended only for the individual(s) to whom it is addressed, and may not be saved, copied,
printed, disclosed or used by anyone else.  If you are not the(an) intended recipient, please
immediately delete this e-mail from your computer system and notify the sender.  Thank you.
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>  
>


-- 
/**
 * Robin Curts
 * rcurts@robincurts.com
 * http://www.robincurts.com
 * (813) 786-8634
 */


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