Thanks for that Chris - very much appreciated,
I did manage to get it to compile but when I click on the link in my
jsp page everything appears except the image - and also no errors -
when I view source it includes the img line for the plot as so:
<IMG SRC="/servlet/OpenFile?plot=/home/kimberly/Desktop/test/52-plot.jpg"
align="left" ALT="plot">
My jsp includes it as this:
<IMG SRC="/servlet/OpenFile?plot=<%=plot%>" align="left" ALT="plot">
Then my serlvet calls the getParameter function to get the absolute
path to the jpeg I want to display in the jsp page.
I might have messed it up when getting it to compile - I was having
problems with the getMimeType method with messages like this:
/usr/local/jdk1.5.0_14/bin/javac -d ../../classes/ OpenFile.java
OpenFile.java:35: cannot find symbol
symbol : method getServletContext()
location: interface javax.servlet.http.HttpServletRequest
ServletContext application = request.getServletContext();
^
OpenFile.java:38: incompatible types
found : java.lang.String
required: java.io.File
return application.getMimeType(file.getName());
^
OpenFile.java:92: setContentType(java.lang.String) in
javax.servlet.ServletResponse cannot be applied to (java.io.File)
response.setContentType(getMimeType(request, file));
^
3 errors
I got rid of the first error by changing and adding these linesin the
getMimeType method:
ServletConfig config = getServletConfig();
ServletContext application = config.getServletContext();
But was still getting the other errors until I commented out the
getMimeType method and placed the above 2 lines in the else before
calling getMimeType - like this:
else
{
ServletConfig config = getServletConfig();
ServletContext application = config.getServletContext();
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType(application.getMimeType(file.getName()));
response.setHeader("Content-Type",String.valueOf(file.length()));
response.setHeader("Content-Disposition","attachment;
filename="+ file.getName());
sendFile(file, response);
}
So now I'm not sure if it's a problem with the way I'm calling it or
if I've messed it up with the changes I've made to it. I've checked
the logs and nothing - no errors there either.
Thanks for all the assistance with this.
Kimberly
On Sat, Mar 22, 2008 at 12:25 AM, Christopher Schultz
<[EMAIL PROTECTED]> wrote:
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> Hash: SHA1
>
> Lars,
>
>
> Lars Nielsen Lind wrote:
> | You can do that with a Servlet. Here are some sample code. Replace
> | content of <> with your own data.
>
> This would be a much better class if it:
>
> * Did not have extraneous class members.
> * Used a buffer for reading and writing to the streams.
> * Did not truncate content-lengths that exceed Integer.MAX_VALUE.
> * Used the proper MIME type (bug!), or allowed the servlet to
> ~ override it.
> * Handled exceptions properly.
> * Returned proper response codes.
> * Included documentation (but hey, it's sample code!)
>
> :(
>
> I point out these problems not to embarrass Lars, but to point out that
> giving code with these kinds of problems to a likely newbie (apologies,
> Kimberly, if you are not a newbie... but your question admits a certain
> level of understanding) does not serve them well. They come to the list
> hoping to get good advice from good developers and you hand them a class
> that is rife with problems.
>
> My guess is that this kind of thing happens all the time and the
> recipient is certainly happy to get some working code, but they don't go
> over it and fix all the problems because it came from someone "smarter"
> than them. Your code may become an example for how to do certain things.
> Given that, we should endeavor to provide the highest quality code
> possible to the readers of this list. We'll be helping them to be better
> programmers.
>
> Allow me to suggest a re-write of this class.
>
> package ...;
>
>
> import java.io.*;
> import java.util.*;
>
> import javax.servlet.*;
> import javax.servlet.http.*;
>
> public class DownloadServlet
> ~ extends HttpServlet
> {
> ~ private static final int BUFFER_SIZE = 4096;
> ~ private static final String BASE_FILE_PATH = "/path/to/your/files";
>
> ~ protected File findFile(HttpServletRequest request)
> ~ throws IOException
> ~ {
> ~ // This is a reasonable default implementation.
> ~ // Feel free to change it.
> ~ File file = new File(BASE_FILE_PATH + request.getPathInfo());
>
> ~ return file;
> ~ }
>
> ~ protected File getMimeType(HttpServletRequest request, File file)
> ~ {
> ~ // This is a reasonable default implementation.
> ~ // Feel free to change it.
> ~ ServletContext application = request.getServletContext();
>
> ~ return application.getMimeType(file.getName());
> ~ }
>
> ~ protected void sendFile(File file, HttpServletResponse response)
> ~ throws IOException
> ~ {
> BufferedInputStream in = null;
>
> ~ try {
> int count;
> ~ byte[] buffer = new byte[BUFFER_SIZE];
>
> ~ in = new BufferedInputStream(new FileInputStream(file));
>
> ~ ServletOutputStream out = response.getOutputStream();
>
> ~ while(-1 != (count = in.read(buffer)))
> ~ out.write(buffer, 0, count);
>
> ~ out.flush();
> ~ }
> ~ finally
> ~ {
> ~ if (in != null)
> ~ {
> ~ try { in.close(); }
> ~ catch (IOException ioe) { /* log an error! */ }
> ~ }
> ~ }
> ~ }
>
> ~ public void service(HttpServletRequest request,
>
> ~ HttpServletResponse response)
> ~ throws ServletException, IOException
> ~ {
> ~ File file = findFile(request);
>
> ~ if(null == file || !file.exists())
> ~ {
> ~ response.sendError(HttpServletResponse.SC_NOT_FOUND);
> ~ }
> ~ else if(!file.canRead())
> ~ {
> ~ // Feel free to send NOT_FOUND instead, if you don't want to
> ~ // give up potentially sensitive security information.
> ~ response.sendError(HttpServletResponse.SC_FORBIDDEN);
> ~ }
> ~ else
> ~ {
> ~ response.setStatus(HttpServletResponse.SC_OK);
> ~ response.setContentType(getMimeType(request, file));
> ~ response.setHeader("Content-Type",
> ~ String.valueOf(file.length());
>
> ~ response.setHeader("Content-Disposition",
> ~ "attachment; filename="
> ~ + file.getName());
>
> ~ sendFile(file, response);
> ~ }
> ~ }
> }
>
> - -chris
>
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>
>
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>
--
Kimberly Begley
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