org.springframework.beans

Class CachedIntrospectionResults

java.lang.Object

org.springframework.beans.CachedIntrospectionResults

public class CachedIntrospectionResults
extends java.lang.Object

Internal class that caches JavaBeans PropertyDescriptor information for a Java class. Not intended for direct use by application code.

Necessary for own caching of descriptors within the application's ClassLoader, rather than rely on the JDK's system-wide BeanInfo cache (in order to avoid leaks on ClassLoader shutdown).

Information is cached statically, so we don't need to create new objects of this class for every JavaBean we manipulate. Hence, this class implements the factory design pattern, using a private constructor and a static forClass(Class) factory method to obtain instances.

Since:

05 May 2001

Author:

Rod Johnson, Juergen Hoeller

See Also:

acceptClassLoader(ClassLoader), clearClassLoader(ClassLoader), forClass(Class)

Field Summary

Fields

Modifier and Type	Field and Description
(package private) static java.util.Set<java.lang.ClassLoader>	acceptedClassLoaders Set of ClassLoaders that this CachedIntrospectionResults class will always accept classes from, even if the classes do not qualify as cache-safe.
private java.beans.BeanInfo	beanInfo The BeanInfo object for the introspected bean class
private static java.util.List<BeanInfoFactory>	beanInfoFactories Stores the BeanInfoFactory instances
(package private) static java.util.Map<java.lang.Class,java.lang.Object>	classCache Map keyed by class containing CachedIntrospectionResults.
private static Log	logger
private java.util.Map<java.lang.String,java.beans.PropertyDescriptor>	propertyDescriptorCache PropertyDescriptor objects keyed by property name String

Constructor Summary

Constructors

Modifier	Constructor and Description
private	CachedIntrospectionResults(java.lang.Class beanClass) Create a new CachedIntrospectionResults instance for the given class.

Method Summary

Modifier and Type	Method and Description
static void	acceptClassLoader(java.lang.ClassLoader classLoader) Accept the given ClassLoader as cache-safe, even if its classes would not qualify as cache-safe in this CachedIntrospectionResults class.
private java.beans.PropertyDescriptor	buildGenericTypeAwarePropertyDescriptor(java.lang.Class beanClass, java.beans.PropertyDescriptor pd)
static void	clearClassLoader(java.lang.ClassLoader classLoader) Clear the introspection cache for the given ClassLoader, removing the introspection results for all classes underneath that ClassLoader, and deregistering the ClassLoader (and any of its children) from the acceptance list.
(package private) static CachedIntrospectionResults	forClass(java.lang.Class beanClass) Create CachedIntrospectionResults for the given bean class.
(package private) java.lang.Class	getBeanClass()
(package private) java.beans.BeanInfo	getBeanInfo()
(package private) java.beans.PropertyDescriptor	getPropertyDescriptor(java.lang.String name)
(package private) java.beans.PropertyDescriptor[]	getPropertyDescriptors()
private static boolean	isClassLoaderAccepted(java.lang.ClassLoader classLoader) Check whether this CachedIntrospectionResults class is configured to accept the given ClassLoader.
private static boolean	isUnderneathClassLoader(java.lang.ClassLoader candidate, java.lang.ClassLoader parent) Check whether the given ClassLoader is underneath the given parent, that is, whether the parent is within the candidate's hierarchy.

Methods inherited from class java.lang.Object

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

Field Detail

logger

private static final Log logger

beanInfoFactories

private static java.util.List<BeanInfoFactory> beanInfoFactories

Stores the BeanInfoFactory instances

acceptedClassLoaders

static final java.util.Set<java.lang.ClassLoader> acceptedClassLoaders

Set of ClassLoaders that this CachedIntrospectionResults class will always accept classes from, even if the classes do not qualify as cache-safe.

classCache

static final java.util.Map<java.lang.Class,java.lang.Object> classCache

Map keyed by class containing CachedIntrospectionResults. Needs to be a WeakHashMap with WeakReferences as values to allow for proper garbage collection in case of multiple class loaders.

beanInfo

private final java.beans.BeanInfo beanInfo

The BeanInfo object for the introspected bean class

propertyDescriptorCache

private final java.util.Map<java.lang.String,java.beans.PropertyDescriptor> propertyDescriptorCache

PropertyDescriptor objects keyed by property name String

Constructor Detail

CachedIntrospectionResults

private CachedIntrospectionResults(java.lang.Class beanClass)
                            throws BeansException

Create a new CachedIntrospectionResults instance for the given class.

Parameters:

beanClass - the bean class to analyze

Throws:

BeansException - in case of introspection failure

Method Detail

acceptClassLoader

public static void acceptClassLoader(java.lang.ClassLoader classLoader)

Accept the given ClassLoader as cache-safe, even if its classes would not qualify as cache-safe in this CachedIntrospectionResults class.

This configuration method is only relevant in scenarios where the Spring classes reside in a 'common' ClassLoader (e.g. the system ClassLoader) whose lifecycle is not coupled to the application. In such a scenario, CachedIntrospectionResults would by default not cache any of the application's classes, since they would create a leak in the common ClassLoader.

Any acceptClassLoader call at application startup should be paired with a clearClassLoader(java.lang.ClassLoader) call at application shutdown.

Parameters:

classLoader - the ClassLoader to accept

clearClassLoader

public static void clearClassLoader(java.lang.ClassLoader classLoader)

Clear the introspection cache for the given ClassLoader, removing the introspection results for all classes underneath that ClassLoader, and deregistering the ClassLoader (and any of its children) from the acceptance list.

Parameters:

classLoader - the ClassLoader to clear the cache for

forClass

static CachedIntrospectionResults forClass(java.lang.Class beanClass)
                                    throws BeansException

Create CachedIntrospectionResults for the given bean class.

We don't want to use synchronization here. Object references are atomic, so we can live with doing the occasional unnecessary lookup at startup only.

Parameters:

beanClass - the bean class to analyze

Returns:

the corresponding CachedIntrospectionResults

Throws:

BeansException - in case of introspection failure

isClassLoaderAccepted

private static boolean isClassLoaderAccepted(java.lang.ClassLoader classLoader)

Check whether this CachedIntrospectionResults class is configured to accept the given ClassLoader.

Parameters:

classLoader - the ClassLoader to check

Returns:

whether the given ClassLoader is accepted

See Also:

acceptClassLoader(java.lang.ClassLoader)

isUnderneathClassLoader

private static boolean isUnderneathClassLoader(java.lang.ClassLoader candidate,
                              java.lang.ClassLoader parent)

Check whether the given ClassLoader is underneath the given parent, that is, whether the parent is within the candidate's hierarchy.

Parameters:

candidate - the candidate ClassLoader to check

parent - the parent ClassLoader to check for

getBeanInfo

java.beans.BeanInfo getBeanInfo()

getBeanClass

java.lang.Class getBeanClass()

getPropertyDescriptor

java.beans.PropertyDescriptor getPropertyDescriptor(java.lang.String name)

getPropertyDescriptors

java.beans.PropertyDescriptor[] getPropertyDescriptors()

buildGenericTypeAwarePropertyDescriptor

private java.beans.PropertyDescriptor buildGenericTypeAwarePropertyDescriptor(java.lang.Class beanClass,
                                                                    java.beans.PropertyDescriptor pd)