Java：数据文件的相对路径

Question

I have developed a GUI application in NetBeans (v. 7.2.1) on Mac (OS version 10.6.8). This application requires an XML file (containing data used by the program), which I would like to place in a subdirectory data .

The trouble is that if I want to run my application from within NetBeans, this data directory has to be placed inside the main project directory; however, if I want to simply run the .jar file (using a doubleclick), located in the dist subdir of the main dir, I have to move the data folder into dist - and then the program will no longer run from within NetBeans.

This is how the data file path is specified within the program:

public String vocabPath = "data" + File.separator + "wordlist.xml";
public File vocabFile = new File(vocabPath);

In itself at first this did not seem problematic, as, for redistribution of the application, I thought I could simply move the data directory into dist , and distribute that (which worked fine on OS X and Windows 7); however, on Ubuntu I got an error message saying the data file was not found.

I am new to Java, so perhaps this is a daft question, but anyway: how can I get my application to always access the data file located in MAIN_DIR/dist/data ? Or if the root of the problem lies somewhere else, then please let me know.

Thanks a lot in advance!

EDIT

I have posted a follow-up question , as I think I have narrowed down the problem to some unexpected behaviour which only occurs under Ubuntu.

EDIT 2

An answer to my follow-up question (see first edit) has solved my problem (just as a note to those who've found this post while trying to solve a problem similar to mine).

Answer 1

If the file wordlist.xml is not modifiable by user, you could include it as part of jar and use getResourceAsStream() to load it. Some additional details are here at getResourceAsStream() vs FileInputStream

if the data is expected to be modified , you may keep it at some known location. Users home directory is available via user.home property. (and is probably a good area)

Having a file relative to 'installation' (MAIN_DIR) is more difficult if it is a pure java program started by java command. You may create an executable and the use some operating system api ( readlink ("/proc/self/exe", ..) on Linux) to resolve the installation location.

Packaging java program with native executable could be done by software like exe4j .

(Launch4J is an opensource solution with similar features, could be useful here)

(For the sake of completion and future reference). You could also try to create a small batch script on windows and shell script on Linux. It is possible to detect the installation area from both.

bat - see %~dp0% - Directory navigation in command prompts .
bash - Getting the source directory of a Bash script from within

Answer 2

I would have kept a System Property for the file and keep the path of dist by default. In case file is present in data which is Development environment the application would pick it up otherwise it will always go to pick up file for dist .

You can do like:

// This would pick up system property if set otherwise default value provided.
String filePath = (String) System.getProperty("VOCAB_FILE_PATH","<<path with dist>>"); 
public File vocabFile = new File(filePath);

In you NetBeans environment just set a system property VOCAB_FILE_PATH with path mentioned as data .