AppConfig (JavaLite - Java, light as a feather 2.5-j8-SNAPSHOT API)

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.

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,V>

Constructor Summary

Constructors
Constructor and Description

AppConfig()

Constructors
Constructor and Description
`AppConfig()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and 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`.
`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 Detail
  - AppConfig
```
public AppConfig()
```
- Method Detail
  - 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.
  - 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.

Class AppConfig

1. Classpath configuration

Example:

2. File configuration

Property substitution

Nested Class Summary

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

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Constructor Detail

AppConfig

Method Detail

setActiveEnv

init

reload

setProperty

getAsProperty

getProperty

p

getAllProperties

size

isEmpty

containsKey

containsValue

get

put

remove

putAll

clear

keySet

values

entrySet

activeEnv

isInTestMode

isInTestEnv

isInProduction

isInDevelopment

isInStaging

getKeys

getProperties

pInteger

pDouble

pFloat

pBoolean