Package org.javalite.app_config

Class AppConfig

java.lang.Object

org.javalite.app_config.AppConfig

All Implemented Interfaces:

Map<String,String>

public class AppConfig
extends Object
implements Map<String,String>

This class allows configuration of applications for different deployment environments, such as development, test, staging, production, etc. Configuration is done either with property files on the classpath, or on a file system.

1. Classpath configuration

Applications could have environment-specific files, whose names follow this pattern: name.properties, where name is a name of a deployment environment, such as "development", "staging", "production", etc. You can also provide a global file, properties from which will be loaded in all environments: global.properties.

In all cases the files need to be on the classpath in package /app_config.

Environment-specific file will have an "environment" part of the file name match to an environment variable called ACTIVE_ENV or system property active_env. The system property will override the environment variable!

Such configuration is easy to achieve in Unix shell:

export ACTIVE_ENV=test

If environment variable ACTIVE_ENV is missing, it defaults to "development".

You can also provide an environment as a system property active_env. System property overrides environment variable ACTIVE_ENV

Example:

If there are four files packed into a /app_config package:

• global.properties
• development.properties
• staging.properties
• production.properties

And the ACTIVE_ENV=staging, then properties will be loaded from the following files:

• global.properties
• staging.properties

2. File configuration

In addition to properties on classpath, you can also specify a single file for properties to loaded from a file system. Use a system property with a full path to a file like:

     java -cp $CLASSPATH com.myproject.Main -Dapp_config.properties=/opt/directory1/myproject.properties
 

The file-based configuration overrides classpath one. If you have a property defined in both, the classpath configuration will be completely ignored and the file property will be used.

3. Environment Variables

You can set the environment variables as well. As long as they are read as usual:

String val = p("env_var_name") 

your program will read these values. The Environment Variables have the highest precedent and will override any other properties defined for this environment.

Property substitution

AppConfig allows a property substitution to make it possible to refactor large property files by specifying a repeating value once. If your property file has these properties:

 first.name=John
   phrase= And the name is ${first.name}
 

than this code will print And the name is John:

 System.out.println(p("phrase"));
 

Note: The order of properties does not matter.

Author:

Igor Polevoy

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
AppConfig()

Method Summary

Modifier and Type	Method	Description
static String	activeEnv()	Returns current environment name as defined by environment variable ACTIVE_ENV.
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<String,String>>	entrySet()
String	get(Object key)
static Map<String,String>	getAllProperties()
static Property	getAsProperty(String key)	Returns property instance corresponding to key.
static List<String>	getKeys(String prefix)	Returns all keys that start with a prefix
static List<String>	getProperties(String prefix)	Return all numbered properties with a prefix.
static String	getProperty(String key)	Returns property value for a key.
static void	init()
boolean	isEmpty()
static boolean	isInDevelopment()
static boolean	isInProduction()
static boolean	isInStaging()
static boolean	isInTestEnv()
static boolean	isInTestMode()	Checks if running in a context of a test by checking of a presence of a class org.junit.Test on classpath.
Set<String>	keySet()
static String	p(String key)	Gets property, synonym for getProperty(String).
static Boolean	pBoolean(String propertyName)	Read property as Boolean.
static Double	pDouble(String propertyName)	Read property as Double.
static Float	pFloat(String propertyName)	Read property as Float.
static Integer	pInteger(String propertyName)	Read property as Integer.
static Long	pLong(String propertyName)	Read property as Long.
String	put(String key, String value)
void	putAll(Map<? extends String,? extends String> m)
static void	reload()	Used in tests.
String	remove(Object key)
static void	setActiveEnv(String activeEnv)	You can change the environment dynamically.
static String	setProperty(String name, String value)	Sets a property in memory.
int	size()
Collection<String>	values()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Details

AppConfig

public AppConfig()

Method Details

setActiveEnv

public static void setActiveEnv(String activeEnv)

You can change the environment dynamically. Attention!!! This method should only be used for tests! Careful out there...

Parameters:

activeEnv - new environment value

init

public static void init()

reload

public static void reload()

Used in tests.

setProperty

public static String setProperty(String name,
 String value)

Sets a property in memory. If property exists, it will be overwritten, if not, a new one will be created.

Parameters:

name - - name of property

value - - value of property

Returns:

old value

getAsProperty

public static Property getAsProperty(String key)

Returns property instance corresponding to key.

Parameters:

key - key for property.

Returns:

Property for this key.

getProperty

public static String getProperty(String key)

Returns property value for a key.

Parameters:

key - key of property.

Returns:

value for this key, null if not found.

p

public static String p(String key)

Gets property, synonym for getProperty(String).

Parameters:

key - key of property

Returns:

property value

getAllProperties

public static Map<String,String> getAllProperties()

size

public int size()

Specified by:

size in interface Map<String,String>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<String,String>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<String,String>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<String,String>

get

public String get(Object key)

Specified by:

get in interface Map<String,String>

put

public String put(String key,
 String value)

Specified by:

put in interface Map<String,String>

remove

public String remove(Object key)

Specified by:

remove in interface Map<String,String>

putAll

public void putAll(Map<? extends String,? extends String> m)

Specified by:

putAll in interface Map<String,String>

clear

public void clear()

Specified by:

clear in interface Map<String,String>

keySet

public Set<String> keySet()

Specified by:

keySet in interface Map<String,String>

values

public Collection<String> values()

Specified by:

values in interface Map<String,String>

entrySet

public Set<Map.Entry<String,String>> entrySet()

Specified by:

entrySet in interface Map<String,String>

activeEnv

public static String activeEnv()

Returns current environment name as defined by environment variable ACTIVE_ENV.

Returns:

current environment name as defined by environment variable ACTIVE_ENV.

isInTestMode

public static boolean isInTestMode()

Checks if running in a context of a test by checking of a presence of a class org.junit.Test on classpath.

Returns:

true if class org.junit.Test is on classpath, otherwise returns false

isInTestEnv

public static boolean isInTestEnv()

Returns:

true if environment name as defined by environment variable ACTIVE_ENV is "testenv".

isInProduction

public static boolean isInProduction()

Returns:

true if environment name as defined by environment variable ACTIVE_ENV is "production".

isInDevelopment

public static boolean isInDevelopment()

Returns:

true if environment name as defined by environment variable ACTIVE_ENV is "development".

isInStaging

public static boolean isInStaging()

Returns:

true if environment name as defined by environment variable ACTIVE_ENV is "staging".

getKeys

public static List<String> getKeys(String prefix)

Returns all keys that start with a prefix

Parameters:

prefix - prefix for properties.

getProperties

public static List<String> getProperties(String prefix)

Return all numbered properties with a prefix. For instance if there is a file:

     prop.1=one
     prop.2=two
 

.. and this method is called:

     List props = AppConfig.getProperties("prop");
 

then the resulting list will have all properties starting from prop. This method presumes consecutive numbers in the suffix.

Parameters:

prefix - prefix of numbered properties.

Returns:

list of property values.

pInteger

public static Integer pInteger(String propertyName)

Read property as Integer.

Parameters:

propertyName - name of property.

Returns:

property as Integer.

pDouble

public static Double pDouble(String propertyName)

Read property as Double.

Parameters:

propertyName - name of property.

Returns:

property as Double.

pLong

public static Long pLong(String propertyName)

Read property as Long.

Parameters:

propertyName - name of property.

Returns:

property as Long.

pFloat

public static Float pFloat(String propertyName)

Read property as Float.

Parameters:

propertyName - name of property.

Returns:

property as Float.

pBoolean

public static Boolean pBoolean(String propertyName)

Read property as Boolean.

Parameters:

propertyName - name of property.

Returns:

property as Boolean.