Content type / MIME mapping question

Greenhorn

Posts: 3

posted 20 years ago

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In Sybex book <<Java 2 Web Developer Certification Study Guide>> :
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When a servlet sends a response to a client, the browser needs to know how to render the information received. Consequently, the server can construct a response to notify the client of the MIME type, by using two different approaches:
. By using the HttpServletResponse�s method: setContentType(�)
. By using the mime-mapping tag in the web.xml file for the web application
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Does it means I could choose either approach?
If I won't call setContentType(...), how could the browser know the content type?
If I have to call setContentType(...), what is mime-mapping for?
Thanks.
[ July 22, 2003: Message edited by: Yong Chen ]

Carl Trusiak

Sheriff

Posts: 3341

posted 20 years ago

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It can know the Mime-type from the extention of the resource requested by the url.

Now, if the url is http://localhost:8080/catalog/page1.pdf The request is going to be serviced by the catalog servlet. Since the extention on the resource is pdf. The Servlet contain knows to set the Mime-type to application/pdf What is cool, if you add a mapping for xml, a simple change of the url to http://localhost:8080/catalog/page1.xml can be rcognized and if you look up the file in your servlet, you don't have to do any lookup to have the content type set properly.

I Hope This Helps
Carl Trusiak, SCJP2, SCWCD

Yong Chen

Greenhorn

Posts: 3

posted 20 years ago

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Still confused.
Do you mean, with url "http://localhost:8080/catalog/page1.pdf", the Servlet container will set the MIME type as "application/pdf" automatically?
If the servlet "catalog" just send a "Hello World" as response, whatever the PathInfo is (page1.pdf or page1.xml), the client browser shows "Hello World".
Even if I set the content type manually:
-------------------------------
res.setContentType("application/pdf");
// or: res.setContentType("text/plain");
PrintWriter out = res.getWriter();
out.println("<http><body><p>Hello world</body></html>");
out.flush();
-------------------------------
the browser treats it as "text/html".
How to explain this?
Thanks,

Sreedevi Vinod

Ranch Hand

Posts: 117

posted 18 years ago

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Is the mime-mapping tag only to replace the setContentType method? Or does it have any other significance ?

Thanks
Devi

Radmika Arunachalam

Ranch Hand

Posts: 45

posted 18 years ago

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Hi,
Which one takes precedence? if i said both mime-mapping and setContentType different, what is the result.. for example

URL is http://localhost:8080/test/test.pdf

mime-mapping is
<extension>pdf</extension>
<mime-type>application/pdf</mime-type>

and i mapped pdf extension to one servlet and in the servlet i am calling setContentType("text/plain");

What is the actual contenttype of the response sent to browser?

Thanks
Radmika

Consider Paul's rocket mass heater.