net.sf.jguiraffe.di.impl

Class ClassDescription

java.lang.Object

net.sf.jguiraffe.di.impl.ClassDescription

public class ClassDescription
extends Object

A helper class for defining references to classes.

Handling of classes can become quite complex because of issues with different class loaders. Because of that the dependency injection framework supports multiple ways of defining classes:

• by directly specifying Class objects; this can be used when the class is already known at compile time
• by providing only the class name; the class will then be resolved using a default class loader
• by providing a class name and a symbolic name for a class loader; this works together with the class loader registration mechanism supported by BeanContext

Instances of this class encapsulate the different ways of specifying a class. They can be initialized with different variants of class descriptions. The getTargetClass() method can be used for obtaining a reference to the wrapped class. Instances are thread-safe and can be shared between multiple components. New instances are created using the static factory methods.

Version:

$Id: ClassDescription.java 205 2012-01-29 18:29:57Z oheger $

Author:

Oliver Heger

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj) Tests the passed in object for equality.
String	getClassLoaderName() Returns the symbolic name of the class loader for resolving the class.
static ClassDescription	getInstance(Class<?> cls) Returns an instance for the specified class.
static ClassDescription	getInstance(String clsName) Returns an instance for the specified class name that will be resolved using the default class loader.
static ClassDescription	getInstance(String clsName, String clsLoaderName) Returns an instance for the specified class name and class loader name.
Class<?>	getTargetClass(ClassLoaderProvider clProvider) Returns the target class of this description.
String	getTargetClassName() Returns the name of the target class of this description.
int	hashCode() Returns a hash code for this object.
String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

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

Method Detail

getTargetClass

public Class<?> getTargetClass(ClassLoaderProvider clProvider)

Returns the target class of this description. The passed in ClassLoaderProvider is used for resolving the class if necessary. This implementation will cache the Class objects when they have been resolved.

Parameters:

clProvider - the ClassLoaderProvider

Returns:

the target class of this description instance

Throws:

InjectionException - if the class cannot be resolved

IllegalArgumentException - if the ClassLoaderProvider is needed, but is null

getTargetClassName

public String getTargetClassName()

Returns the name of the target class of this description.

Returns:

the name of the target class

getClassLoaderName

public String getClassLoaderName()

Returns the symbolic name of the class loader for resolving the class. This can be null if the default class loader is to be used.

Returns:

the name of the class loader to use

equals

public boolean equals(Object obj)

Tests the passed in object for equality. Two objects of this class are considered equal if they have the same target class name and class loader name.

Overrides:

equals in class Object

Parameters:

obj - the object to compare to

Returns:

a flag whether the objects are equal

hashCode

public int hashCode()

Returns a hash code for this object.

Overrides:

hashCode in class Object

Returns:

a hash code

toString

public String toString()

Returns a string representation of this object. This string will contain the name of the target class. If a class loader name is specified, this name will also be contained in the resulting string.

Overrides:

toString in class Object

Returns:

a string for this object

getInstance

public static ClassDescription getInstance(Class<?> cls)

Returns an instance for the specified class. This method can be used when the target class is already known at compile time.

Parameters:

cls - the target class

Returns:

the description instance for this class

getInstance

public static ClassDescription getInstance(String clsName,
                                           String clsLoaderName)

Returns an instance for the specified class name and class loader name. The target class will be resolved using reflection. It is loaded from the class loader with the given symbolic name.

Parameters:

clsName - the name of the class

clsLoaderName - the symbolic name of the class loader

Returns:

the description instance for this class

getInstance

public static ClassDescription getInstance(String clsName)

Returns an instance for the specified class name that will be resolved using the default class loader.

Parameters:

clsName - the name of the class

Returns:

the description instance for this class