So, you need a directory where you can write files and serve them to
the web, and you don't want that directory to be hard-coded in your
application.
First, you need a way to specify the directory when the app is
installed. (In general your app may need a bunch of configuration
settings.) There are various places that you can put these settings -
<context-param> in web.xml, a config file read by the webapp, a
database table, etc. The way that your servlets and JSP pages access
these settings depends on how they're stored.
In my app, I store these settings in the database, and set up a
variable so that image files are specified in JSP as
"${imageFiles}/image1.jpg", which comes out as
"/appfiles/images/image1.jpg" (or whatever).
Then, when the app is installed and configured, the admin has to set
up a directory that is writable by Tomcat, and is published on the
web. For stand-alone Tomcat, this can be a directory in the ROOT
webapp, e.g. $CATALINA_BASE/ROOT/appfiles/images. If Tomcat is fronted
by a web server, the image files could be served by the web server.
The admin has to set two settings for your app: the URL to access the
directory (e.g. "/appfiles/images") and the file system pathname for
the same directory, so you know where to write the files (e.g.
"$CATALINA_BASE/ROOT/appfiles/images").
Hope this helps.
--
Len
On 8/7/06, Romain Quilici <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> 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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![http://yourdomain/images/1.jpg"](http://yourdomain/images/1.jpg"){kind=link}