org.apache.commons.discovery.tools
Class ManagedProperties

java.lang.Object
  |
  +--org.apache.commons.discovery.tools.ManagedProperties

public class ManagedProperties

extends java.lang.Object

This class may disappear in the future, or be moved to another project..

Extend the concept of System properties to a hierarchical scheme based around class loaders. System properties are global in nature, so using them easily violates sound architectural and design principles for maintaining separation between components and runtime environments. Nevertheless, there is a need for properties broader in scope than class or class instance scope.

This class is one solution.

Manage properties according to a secure scheme similar to that used by classloaders:

• ClassLoaders are organized in a tree hierarchy.
• each ClassLoader has a reference to a parent ClassLoader.
• the root of the tree is the bootstrap ClassLoaderer.
• the youngest decendent is the thread context class loader.
• properties are bound to a ClassLoader instance
  • non-default properties bound to a parent ClassLoader instance take precedence over all properties of the same name bound to any decendent. Just to confuse the issue, this is the default case.
  • default properties bound to a parent ClassLoader instance may be overriden by (default or non-default) properties of the same name bound to any decendent.
• System properties take precedence over all other properties

This is not a perfect solution, as it is possible that different ClassLoaders load different instances of ScopedProperties. The 'higher' this class is loaded within the ClassLoader hierarchy, the more usefull it will be.

Author:

Richard A. Sitze

Constructor Summary

ManagedProperties()

Method Summary

static java.util.Properties	getProperties() This is an expensive operation.
static java.lang.String	getProperty(java.lang.ClassLoader classLoader, java.lang.String propertyName) Get value for property bound to the class loader.
static java.lang.String	getProperty(java.lang.ClassLoader classLoader, java.lang.String propertyName, java.lang.String dephault) Get value for property bound to the class loader.
static java.lang.String	getProperty(java.lang.String propertyName) Get value for property bound to the current thread context class loader.
static java.lang.String	getProperty(java.lang.String propertyName, java.lang.String dephault) Get value for property bound to the current thread context class loader.
static java.util.Enumeration	propertyNames() Return list of all property names.
static void	setProperties(java.util.Map newProperties) Set property values for Properties bound to the current thread context class loader.
static void	setProperties(java.util.Map newProperties, boolean isDefault) Set property values for Properties bound to the current thread context class loader.
static void	setProperty(java.lang.String propertyName, java.lang.String value) Set value for property bound to the current thread context class loader.
static void	setProperty(java.lang.String propertyName, java.lang.String value, boolean isDefault) Set value for property bound to the current thread context class loader.

Methods inherited from class java.lang.Object

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

Constructor Detail

ManagedProperties

public ManagedProperties()

Method Detail

getProperty

public static java.lang.String getProperty(java.lang.String propertyName)

Get value for property bound to the current thread context class loader.

Parameters:

property - property name.

Returns:

property value if found, otherwise default.

getProperty

public static java.lang.String getProperty(java.lang.String propertyName,
                                           java.lang.String dephault)

Get value for property bound to the current thread context class loader. If not found, then return default.

Parameters:

property - property name.

dephault - default value.

Returns:

property value if found, otherwise default.

getProperty

public static java.lang.String getProperty(java.lang.ClassLoader classLoader,
                                           java.lang.String propertyName)

Get value for property bound to the class loader.

Parameters:

classLoader -

property - property name.

Returns:

property value if found, otherwise default.

getProperty

public static java.lang.String getProperty(java.lang.ClassLoader classLoader,
                                           java.lang.String propertyName,
                                           java.lang.String dephault)

Get value for property bound to the class loader. If not found, then return default.

Parameters:

classLoader -

property - property name.

dephault - default value.

Returns:

property value if found, otherwise default.

setProperty

public static void setProperty(java.lang.String propertyName,
                               java.lang.String value)

Set value for property bound to the current thread context class loader.

Parameters:

property - property name

value - property value (non-default) If null, remove the property.

setProperty

public static void setProperty(java.lang.String propertyName,
                               java.lang.String value,
                               boolean isDefault)

Set value for property bound to the current thread context class loader.

Parameters:

property - property name

value - property value. If null, remove the property.

isDefault - determines if property is default or not. A non-default property cannot be overriden. A default property can be overriden by a property (default or non-default) of the same name bound to a decendent class loader.

setProperties

public static void setProperties(java.util.Map newProperties)

Set property values for Properties bound to the current thread context class loader.

Parameters:

newProperties - name/value pairs to be bound

setProperties

public static void setProperties(java.util.Map newProperties,
                                 boolean isDefault)

Set property values for Properties bound to the current thread context class loader.

Parameters:

newProperties - name/value pairs to be bound

isDefault - determines if properties are default or not. A non-default property cannot be overriden. A default property can be overriden by a property (default or non-default) of the same name bound to a decendent class loader.

propertyNames

public static java.util.Enumeration propertyNames()

Return list of all property names. This is an expensive operation: ON EACH CALL it walks through all property lists associated with the current context class loader upto and including the bootstrap class loader.

getProperties

public static java.util.Properties getProperties()

This is an expensive operation. ON EACH CALL it walks through all property lists associated with the current context class loader upto and including the bootstrap class loader.

Returns:

Returns a java.util.Properties instance that is equivalent to the current state of the scoped properties, in that getProperty() will return the same value. However, this is a copy, so setProperty on the returned value will not effect the scoped properties.