org.springframework.core.env
Class PropertySource<T>

java.lang.Object
  org.springframework.core.env.PropertySource<T>

Direct Known Subclasses:

EnumerablePropertySource, JndiPropertySource, PropertySource.StubPropertySource

public abstract class PropertySource<T>
extends Object

Abstract base class representing a source of key/value property pairs. The underlying source object may be of any type T that encapsulates properties. Examples include Properties objects, Map objects, ServletContext and ServletConfig objects (for access to init parameters). Explore the PropertySource type hierarchy to see provided implementations.

PropertySource objects are not typically used in isolation, but rather through a PropertySources object, which aggregates property sources and in conjunction with a PropertyResolver implementation that can perform precedence-based searches across the set of PropertySources.

PropertySource identity is determined not based on the content of encapsulated properties, but rather based on the name of the PropertySource alone. This is useful for manipulating PropertySource objects when in collection contexts. See operations in MutablePropertySources as well as the named(String) and toString() methods for details.

Since:

3.1

Author:

Chris Beams

See Also:

PropertySources, PropertyResolver, PropertySourcesPropertyResolver, MutablePropertySources

Nested Class Summary

static class

PropertySource.StubPropertySource PropertySource to be used as a placeholder in cases where an actual property source cannot be eagerly initialized at application context creation time.

Field Summary

protected Log	logger
protected String	name
protected T	source

Constructor Summary

PropertySource(String name)
Create a new PropertySource with the given name and with a new Object instance as the underlying source.

PropertySource(String name, T source)
Create a new PropertySource with the given name and source object.

Method Summary

boolean	containsProperty(String key) Return whether this PropertySource contains the given key.
boolean	equals(Object obj) This PropertySource object is equal to the given object if: they are the same instance the name properties for both objects are equal
String	getName() Return the name of this PropertySource
abstract Object	getProperty(String key) Return the value associated with the given key, null if not found.
T	getSource() Return the underlying source object for this PropertySource.
int	hashCode() Return a hashcode derived from the name property of this PropertySource object.
static PropertySource<?>	named(String name) Return a PropertySource implementation intended for collection comparison purposes only.
String	toString() Produce concise output (type and name) if the current log level does not include debug.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

logger

protected final Log logger

name

protected final String name

source

protected final T source

Constructor Detail

PropertySource

public PropertySource(String name,
                      T source)

Create a new PropertySource with the given name and source object.

PropertySource

public PropertySource(String name)

Create a new PropertySource with the given name and with a new Object instance as the underlying source.

Often useful in testing scenarios when creating anonymous implementations that never query an actual source, but rather return hard-coded values.

Method Detail

getName

public String getName()

Return the name of this PropertySource

getSource

public T getSource()

Return the underlying source object for this PropertySource.

containsProperty

public boolean containsProperty(String key)

Return whether this PropertySource contains the given key.

This implementation simply checks for a null return value from getProperty(String). Subclasses may wish to implement a more efficient algorithm if possible.

Parameters:

key - the property key to find

getProperty

public abstract Object getProperty(String key)

Return the value associated with the given key, null if not found.

Parameters:

key - the property key to find

See Also:

PropertyResolver.getRequiredProperty(String)

hashCode

public int hashCode()

Return a hashcode derived from the name property of this PropertySource object.

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

This PropertySource object is equal to the given object if:

• they are the same instance
• the name properties for both objects are equal

No properties other than name are evaluated.

Overrides:

equals in class Object

toString

public String toString()

Produce concise output (type and name) if the current log level does not include debug. If debug is enabled, produce verbose output including hashcode of the PropertySource instance and every key/value property pair. This variable verbosity is useful as a property source such as system properties or environment variables may contain an arbitrary number of property pairs, potentially leading to difficult to read exception and log messages.

Overrides:

toString in class Object

See Also:

Log.isDebugEnabled()

named

public static PropertySource<?> named(String name)

Return a PropertySource implementation intended for collection comparison purposes only.

Primarily for internal use, but given a collection of PropertySource objects, may be used as follows:

 List<PropertySource<?>> sources = new ArrayList<PropertySource<?>>();
   sources.add(new MapPropertySource("sourceA", mapA));
   sources.add(new MapPropertySource("sourceB", mapB));
   assert sources.contains(PropertySource.named("sourceA"));
   assert sources.contains(PropertySource.named("sourceB"));
   assert !sources.contains(PropertySource.named("sourceC"));
 
 

The returned PropertySource will throw UnsupportedOperationException if any methods other than equals(Object), hashCode(), and toString() are called.

Parameters:

name - the name of the comparison PropertySource to be created and returned.