This week's book giveaway is in the Servlets forum.
We're giving away four copies of Murach's Java Servlets and JSP and have Joel Murach on-line!
See this thread for details.
The moose likes Servlets and the fly likes Problems with file i/o Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login


Win a copy of Murach's Java Servlets and JSP this week in the Servlets forum!
JavaRanch » Java Forums » Java » Servlets
Bookmark "Problems with file i/o" Watch "Problems with file i/o" New topic
Author

Problems with file i/o

Micah Wedemeyer
Ranch Hand

Joined: Jun 11, 2001
Posts: 68
I'll try to give as much information as possible to make this easiest. I added some errata info at the bottom.
The problem: I cannot get my servlet to correctly read and write files. I tried just using straight out file paths, but I ran into the system-dependent/container problem of what the actual path is. To combat this, I attempted to use getContext().getRealPath(String x), but I have been having problems with that.
I am attempting to write to a file, and if it is not present, then I must create it. I heard that getRealPath will return null if the file in question does not exist or if there is a problem determining its location. In my case, getRealPath always seems to return null, even when looking for simple things. I decided to test it and used getRealPath("/index.html") and even this returned null, although I am sure the file is there.
All I need to know is how to get to my file! I am taking input from an HTML form, then putting it into a List then writing the list to a file. Each time someone new submits the form, my program reads the list from the file, adds a new node, then writes it back out. At the end of the week, I use another application to read the file and see who guessed correctly. If there is a better way to do this, please let me know! Also, I do not have access to any database tools nor do I have any DB programming experience. Besides, I will never have more than 500 entries in my list, so hardcore database stuff isn't necessary.
Notes:
First, I'm using JRun 2.3 running on a Macintosh WebSTAR 4.2 I don't know anything about either of those except JRun is nowhere near as good as Tomcat, and WebSTAR sucks compared to Apache.
Second, I can't install Tomcat and I can't get another server. As much as I'd like to, it's not my equipment, it's my boss's.
Lastly, my servlet is self-contained in a .jar file. I have heard of .war files, but I have not been able to find much information about them. I mention this because 1) I could not get JRun to run my servlet when it was extracted and 2) I read that getRealPath() gets weird when used with a .war
Kalaiselvan Selvamani
Ranch Hand

Joined: Sep 10, 2001
Posts: 32
I think the problem is getServletContext().getRealPath();
try this one
If u are using JRUN3.1 use getServletInfo().getServletContext().getRealPath()
Micah Wedemeyer
Ranch Hand

Joined: Jun 11, 2001
Posts: 68
I am using JRun 2.3 and I cannot upgrade since 3+ is not for Macintosh.
I'll give it a shot, though.
Micah
Rama Raghavan
Ranch Hand

Joined: Aug 22, 2001
Posts: 116

Try to do this
File anyFile = new File("/index.html");
Then print the path anyFile.getAbsolutePath()
You will notice that the path here may not correspond to the root of your webapp. Instead it may be a different location (may be the location of JRun server startup location..)
This might give you a clue why your file i/o is not finding the file..!!
------------------
_________________________
Rama Raghavan
SCJP2


Rama Raghavan<br />SCJP2<br />SCWCD
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Problems with file i/o
 
Similar Threads
Is it possible to list files under certain folder with servlet
Problems getting Tomcat to work without Eclipse IDE
getRealPath() returns null using Weblogic
Reading a File in Servlet from Web App Directory
Having problems with Security