Property Loader

Table of contents

What Is It
Quick Start
Postprocessing Features
Advanced Configuration
Javadoc
How To Contribute

What is it

The Property Loader is a Java library for managing property configurations.

It supports several property loading strategies and features e.g.:

1. Hierarchical/Ordered property loading (Master, User, System properties ....)
2. Property templates
3. Recursive property resolution
4. Property encryption

Quick start

1. Get the code:

$ git clone git@github.com:TNG/property-loader.git

2. Build the library:

$ mvn install

3. Include jar file to your application
4. Add property files e.g. props.properties to your application's classpath
5. Load properties:

PropertyLoader propertyLoader = new PropertyLoader().withDefaultConfig();

// loads: "props.properties", "props.$hostname.properties", "props.$user.properties"
Properties properties = propertyLoader.load("props")

Postprocessing features

1. Variable resolving

Variables in property values can be defined with:

{$...}

Even nested variables are allowed, e.g.:

{$var{$innervar}e}

In the case above, the PropertyLoader will first resolve the inner variable, replace it, then resolve the outer variable.

2. Includes

In order to include additional properties files from a properties file, add %include as a key with the file basenames separated by commas as its value, e.g.:

%include=file1,file2,file3

3. Decryption

Encrypted property values that are prefixed with DECRYPT: will be decrypted after loading.

Advanced configuration

The PropertyLoader's default configuration includes default search paths, suffixes and applies all available postprocessing filters.

The default search paths are:

1. the current directory
2. the user's home directory
3. the context classpath

The default suffixes are:

1. local host names
2. the user name
3. 'override'

1. Search locations

Tell the PropertyLoader to search for properties files at its default locations (user's home directory, current directory and context classpath):

propertyLoader.atDefaultLocations()

1.1 Folders and URLs

Tell the PropertyLoader to search for properties files at custom paths:

propertyLoader.atDirectory(String directory)
propertyLoader.atBaseURL(URL url)
propertyLoader.atCurrentDirectory()
propertyLoader.atHomeDirectory()

1.2 Classpath

Tell the PropertyLoader to search for properties files in the current thread's classpath:

propertyLoader.atContextClassPath()

This will get the classloader from the current thread and use it to find properties files.

1.3 Classloader

Tell the PropertyLoader to search for properties files using a custom ClassLoader:

propertyLoader.atClassLoader(ClassLoader classLoader)

1.4 Relative to a class

Tell the PropertyLoader to search for properties files relative to the location of a class:

propertyLoader.atRelativeToClass(Class<?> clazz)

2. Suffixes

Tell the PropertyLoader to use default suffixes (local host names, user name and "override"):

propertyLoader.addDefaultSuffixes()

Tell the PropertyLoader to use custom suffixes:

propertyLoader.addSuffix(String directory)
propertyLoader.addSuffixList(List<String> suffixes)
propertyLoader.addUserName()
propertyLoader.addLocalHostNames()

3. Postprocessing

You can define which postprocessing filters are applied (includes are always processed if the key is present):

propertyLoader.withDefaultFilters()
propertyLoader.withVariableResolvingFilter()
propertyLoader.withEnvironmentResolvingFilter()
propertyLoader.withDecryptingFilter()
propertyLoader.withWarnIfPropertyHasToBeDefined()
propertyLoader.withWarnOnSurroundingWhitespace()

Javadoc

Full Javadoc of the code can be found here http://tng.github.io/property-loader/.

How to contribute

Please have a look at CONTRIBUTING.md.