org.apache.velocity.util.introspection
Class IntrospectorBase

java.lang.Object
  org.apache.velocity.util.introspection.IntrospectorBase

All Implemented Interfaces:

IntrospectorCacheListener

Direct Known Subclasses:

Introspector

public abstract class IntrospectorBase
extends Object
implements IntrospectorCacheListener

Lookup a a Method object for a particular class given the name of a method and its parameters. The first time the Introspector sees a class it creates a class method map for the class in question. Basically the class method map is a Hashtable where Method objects are keyed by a concatenation of the method name and the names of classes that make up the parameters. For example, a method with the following signature: public void method(String a, StringBuffer b) would be mapped by the key: "method" + "java.lang.String" + "java.lang.StringBuffer" This mapping is performed for all the methods in a class and stored for.

Version:

$Id: IntrospectorBase.java 477003 2006-11-20 01:14:22Z henning $

Author:

Jason van Zyl, Bob McWhirter, Attila Szegedi, Paulo Gaspar, Henning P. Schmiedehausen

Field Summary

protected Log

log Class logger

Constructor Summary

protected

IntrospectorBase(Log log) C'tor.

Method Summary

protected void	clearCache() Deprecated. Use getIntrospectorCache().clear();
protected ClassMap	createClassMap(Class c) Deprecated. Use getIntrospectorCache().put(c);
protected IntrospectorCache	getIntrospectorCache() Return the internal IntrospectorCache object.
Method	getMethod(Class c, String name, Object[] params) Gets the method defined by name and params for the Class c.
protected ClassMap	lookupClassMap(Class c) Deprecated. Use getIntrospectorCache().get(c);
void	triggerClear() Gets called when the Cache is cleared.
void	triggerGet(Class c, ClassMap classMap) Gets called when a ClassMap is requested from the Cache.
void	triggerPut(Class c, ClassMap classMap) Gets called when a ClassMap is put into the Cache.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected final Log log

Class logger

Constructor Detail

IntrospectorBase

protected IntrospectorBase(Log log)

C'tor.

Method Detail

getMethod

public Method getMethod(Class c,
                        String name,
                        Object[] params)
                 throws IllegalArgumentException,
                        MethodMap.AmbiguousException

Gets the method defined by name and params for the Class c.

Parameters:

c - Class in which the method search is taking place

name - Name of the method being searched for

params - An array of Objects (not Classes) that describe the the parameters

Returns:

The desired Method object.

Throws:

IllegalArgumentException - When the parameters passed in can not be used for introspection.

MethodMap.AmbiguousException - When the method map contains more than one match for the requested signature.

getIntrospectorCache

protected IntrospectorCache getIntrospectorCache()

Return the internal IntrospectorCache object.

Returns:

The internal IntrospectorCache object.

clearCache

protected void clearCache()

Deprecated. Use getIntrospectorCache().clear();

Clears the internal cache.

createClassMap

protected ClassMap createClassMap(Class c)

Deprecated. Use getIntrospectorCache().put(c);

Creates a class map for specific class and registers it in the cache. Also adds the qualified name to the name->class map for later Classloader change detection.

Parameters:

c - The class for which the class map gets generated.

Returns:

A ClassMap object.

lookupClassMap

protected ClassMap lookupClassMap(Class c)

Deprecated. Use getIntrospectorCache().get(c);

Lookup a given Class object in the cache. If it does not exist, check whether this is due to a class change and purge the caches eventually.

Parameters:

c - The class to look up.

Returns:

A ClassMap object or null if it does not exist in the cache.

triggerClear

public void triggerClear()

Description copied from interface: IntrospectorCacheListener

Gets called when the Cache is cleared.

Specified by:

triggerClear in interface IntrospectorCacheListener

See Also:

IntrospectorCacheListener.triggerClear()

triggerGet

public void triggerGet(Class c,
                       ClassMap classMap)

Description copied from interface: IntrospectorCacheListener

Gets called when a ClassMap is requested from the Cache.

Specified by:

triggerGet in interface IntrospectorCacheListener

Parameters:

c - The class object to look up.

classMap - The Class map to return. Might be null.

See Also:

IntrospectorCacheListener.triggerGet(Class, ClassMap)

triggerPut

public void triggerPut(Class c,
                       ClassMap classMap)

Description copied from interface: IntrospectorCacheListener

Gets called when a ClassMap is put into the Cache.

Specified by:

triggerPut in interface IntrospectorCacheListener

Parameters:

c - The class object to look up.

classMap - The Class map stored in the Cache. Is never null.

See Also:

IntrospectorCacheListener.triggerPut(Class, ClassMap)