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From "Almir Kazazic" <kaza...@gmail.com>
Subject Re: Writing files accessible from a browser
Date Mon, 07 Aug 2006 07:49:40 GMT
Hi,

to avoid using absolut paths you can find that out on runtime by

getContext().getRealPath("/") - will return your path to the root

regards


On 8/7/06, Romain Quilici <r.quilici@chem.usyd.edu.au> wrote:
> Hi,
> Hope I will be clear enough:
>
> One part of my web application receives encodes stream that it has to
> convert to jpg images. When an image is written on the server, it
> notifies a Servlet  which pushes the  name (or the url) of the newly
> generated image inside client browser(thanks to pushlets  technology).
> The Servlet can only push a String (Pushlets requirements).
>
> So my problem is where can I write the images, so they can be accessible
> by a URL. One easy solution, the one I use for testing, is to hardcode
> in my webapp the directory where the images are written.
> For instance TOMCAT_HOME\webapps\frames\,
> and in my jsp to have <img src="http://myserver/frames/name.jpg> where
> name.jpg is pushed by the servlet when this image is generated.
>
> However, this solution is not satisfactory, indeed, if I deploy my
> application in another place, I don't want people to edit my code to
> change for suitable values. I admit I could use properties or a
> configuration file to set these value(even if I am not sure it would
> work in all configuration), anyway I would like to check if using the
> servletcontext, or other solutions might be more appropriate.
> As I said a solution with the temp directory would be perfect, if this
> directory was accessible with a URL
>
> Hope it is clear
> Regards
> Li wrote:
> > Hi,
> >
> > It is not advisable to make your webapp dir writable, can you tell me
> > what exactly would you like to achieve so that I may get more info to
> > help out ...
> >
> >
> >
> > On 8/7/06, Romain Quilici <r.quilici@chem.usyd.edu.au> wrote:
> >> Hi,
> >> thanks for the advice,
> >> But I want to avoid harcoded links such as $APACHE_HOME\httpdocs\images
> >> or <a href="http://yourdomain/images/1.jpg"> in my jsp.
> >>
> >> Indeed I don't want to modify these values if I decide Tomcat to run on
> >> another port, or to install Tomcat in another directory or even OS. That
> >> is why I am looking for an approach using
> >> the webapp context, so I don't have to worry about the OS, or the port,
> >> or whatever configuration.
> >> Anyway thanks for your help
> >> Regards
> >> Romain
> >>
> >> Li wrote:
> >> > Hi,
> >> >
> >> > Here are few steps of achieving it (just tested, and it works):
> >> > 1. use FileOutputStream or any output streaming object to write a
> >> > image file
> >> >    into the directory
> >> >   in Windows, the path string should look like:
> >> > "c:\apache_home\httpdocs\images\1.jpg"
> >> >   in unix/linux, the path should look like
> >> > $APACHE_HOME\httpdocs\images\1.jpg"
> >> >   (assume, you had defined APACHE_HOME, make sure the images folder
> >> > is read/write
> >> >   only for the user/group that runs tomcat
> >> > 2. Make sure apache is on ...
> >> > 3. in your jsp: use
> >> >   e.g. <a href="http://yourdomain/images/1.jpg">click to view</a>
> >> >
> >> >
> >> > Wish it helps
> >> >
> >> > On 8/7/06, Romain Quilici <r.quilici@chem.usyd.edu.au> wrote:
> >> >> Thanks for the answer,
> >> >> this solution was part of my investigation, and was actually the
> >> first
> >> >> idea I had.
> >> >> The problem with this approach is I don't know how to access the
> >> >> /image_dir/ from within my web application.
> >> >> Maybe using something like
> >> >> String path = servletContext.getRealPath("/");
> >> >> String imagePath = path+"../image_dir/"
> >> >> and use the imagePath to create my images, then in my jsp
> >> something like
> >> >> <request.getContextPath()/../image_dir/image1.jpg>
> >> >>
> >> >> But I am not sure this approach works in all configurations,
> >> >> particularly if my webapp is deployed inside a war.
> >> >>
> >> >> Thanks
> >> >> Romain
> >> >>
> >> >> Li wrote:
> >> >> > if you have apache server, you can write file to its home dir,
and
> >> >> > then use
> >> >> > http://<youdomain>/<image_dir>/image_name.suffix to
view.
> >> >> >
> >> >> > On 8/7/06, Romain Quilici <r.quilici@chem.usyd.edu.au> wrote:
> >> >> >> Hi all,
> >> >> >> I have been reading several messages about writing files inside
> >> a web
> >> >> >> application, but I found no answer regarding my problem.
> >> >> >>
> >> >> >> I need to write files on the file system that can be accessible
> >> >> with a
> >> >> >> browser(I write images).
> >> >> >>
> >> >> >> - The most reliable solution I found was to use the webapp's
tmp
> >> >> >> directory, unfortunately this directory is not accessible
with
> >> a URL.
> >> >> >>
> >> >> >> - Another solution would be to write these images under my
webapp
> >> >> >> root(or in another place under my webapp). But it seems that
this
> >> >> >> approach does not work with webapps deployed in a war file.
> >> >> >> Indeed you cannot write inside wars like this.
> >> >> >>
> >> >> >> I don't want to rely on some hardcoded solutions. There is
> >> still the
> >> >> >> possibility to pass the absolute path to the directory (let's
say
> >> >> >> TOMCAT_HOME/webapps/myimages/) and later, use inside my JSP
> >> >> >> <request.getContextPath()/../myimages/image1.jpg>, but
I think
> >> this
> >> >> >> solution won't work in many configurations
> >> >> >>
> >> >> >> Thanks a lot for your help
> >> >> >> Regards
> >> >> >> Romain
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >>
> >> ---------------------------------------------------------------------
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> >> >> >>
> >> >> >>
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >> ---------------------------------------------------------------------
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> >> >>
> >> >>
> >> >
> >> >
> >>
> >>
> >>
> >> ---------------------------------------------------------------------
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> >>
> >>
> >
> >
>
>
>
> ---------------------------------------------------------------------
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