How do I access a config file inside the jar?

Question

I'm using FlatPack to parse and load data from flat files. This requires loading a config file that stores mappings of the columns of the flat file.

I have a constant to define the location of the mapping file:

private static final String MAPPING_FILE = "src/com/company/config/Maping.pzmap.xml";

I have a parse(File dataFile) method that actually does the parsing:

private void parse(File dataFile) throws FileNotFoundException, SQLException { Parser parser; log.info("Parsing " + dataFile.getName()); FileReader mappingFileReader = new FileReader(MAPPING_FILE); FileReader dataFileReader = new FileReader(dataFile); parser = DefaultParserFactory.getInstance().newFixedLengthParser(mappingFileReader, dataFileReader); parser.setHandlingShortLines(true); DataSet dataSet = parser.parse(); //process the data }

When I jar up everything and run it as a jar - it bombs out on FileReader mappingFileReader = new FileReader(MAPPING_FILE); with a FileNotFoundException. That file is inside the jar though.

How do I get to it?

I've looked at this question and this question about accessing files inside jars and they both recommend temporarily extracting the file. I don't want to do that though.

guerda · Accepted Answer · 2009-06-03 13:17:21Z

15

if it's inside a JAR, it's not a File, generally speaking. You should load the data using Class.getResourceAsStream(String), or something similar.

edited Jun 3, 2009 at 13:17

guerda

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answered Jun 3, 2009 at 13:03

skaffman

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1 Comment

mtpettyp Over a year ago

That should be "Class.getResourceAsStream()"

ahmet alp balkan · Accepted Answer · 2009-06-03 13:04:53Z

I think it is solved just here:

http://www.velocityreviews.com/forums/t129474-beginner-question-how-to-access-an-xml-file-inside-a-jar-without-extracting-it.html

Billy · Accepted Answer · 2009-06-03 15:58:10Z

If I remember correctly, getResourceAsStream() can behave differently depending on which web server your webapp is deployed, for instance I think it can be a problem when deployed as a war on a Websphere instance. But I'm not sure if this applies to you.

But I'm not sure you're trying to solve the "proper" problem : if it's a config file, that means is data dependant right ? Not code dependant ( your jar ) ? When the flat file will change, your config file will need to change as well, right ? If this is true, it sounds like the config should be better stored elsewhere, or even passed as a parameter to your jar.

But maybe I haven't fully understood your problem...

user115086 · Accepted Answer · 2009-06-03 17:27:45Z

Use Apache Commons Configuration, then you can read/write XML, auto update, find config file in path or jar, without a lot of hassles.

Shubham Jain · Accepted Answer · 2023-03-30 16:39:41Z

Use Below code in your config file

InputStream in = Class.getClassLoader().getResourceAsStream(configFilePath);

Note : replace the classname with your Config class

Demo Full code :

Imports:

import java.io.IOException; import java.io.InputStream; import java.util.Properties;

Code:

 Properties properties = new Properties(); InputStream in = MyCLassName.class.getClassLoader().getResourceAsStream(configFilePath); //pass the config.properties file path with file name try { properties.load(in); properties.getProperty("username"); //here put the key from config.properties } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }

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