org.apache.velocity.util.introspection

Class ClassMap


public class ClassMap
extends java.lang.Object

A cache of introspection information for a specific class instance. Keys java.lang.Method objects by a concatenation of the method name and the names of classes that make up the parameters.
Version:
$Id: ClassMap.java,v 1.20.8.1 2004/03/03 23:23:08 geirm Exp $
Authors:
Jason van Zyl
Bob McWhirter
Attila Szegedi
Geir Magnusson Jr.

Nested Class Summary

private static class
ClassMap.CacheMiss
private static class
ClassMap.MethodInfo
Used for the iterative discovery process for public methods.

Field Summary

private static ClassMap.CacheMiss
CACHE_MISS
private static Object
OBJECT
private Class
clazz
Class passed into the constructor used to as the basis for the Method map.
private Map
methodCache
Cache of Methods, or CACHE_MISS, keyed by method name and actual arguments used to find it.
private MethodMap
methodMap

Constructor Summary

ClassMap()
ClassMap(Class clazz)
Standard constructor

Method Summary

Method
findMethod(String name, Object[] params)
Find a Method using the methodKey provided.
private static Method[]
getAccessibleMethods(Class clazz)
Retrieves public methods for a class.
private static int
getAccessibleMethods(Class clazz, ClassMap.MethodInfo[] methodInfos, int upcastCount)
Recursively finds a match for each method, starting with the class, and then searching the superclass and interfaces.
(package private) Class
getCachedClass()
private static Method
getPublicMethod(Class clazz, String name, Class[] paramTypes)
Looks up the method with specified name and signature in the first public superclass or implemented interface of the class.
static Method
getPublicMethod(Method method)
For a given method, retrieves its publicly accessible counterpart.
private String
makeMethodKey(Method method)
Make a methodKey for the given method using the concatenation of the name and the types of the method parameters.
private static String
makeMethodKey(String method, Object[] params)
private void
populateMethodCache()
Populate the Map of direct hits.

Field Details

CACHE_MISS

private static final ClassMap.CacheMiss CACHE_MISS

OBJECT

private static final Object OBJECT

clazz

private Class clazz
Class passed into the constructor used to as the basis for the Method map.

methodCache

private Map methodCache
Cache of Methods, or CACHE_MISS, keyed by method name and actual arguments used to find it.

methodMap

private MethodMap methodMap

Constructor Details

ClassMap

private ClassMap()

ClassMap

public ClassMap(Class clazz)
Standard constructor

Method Details

findMethod

public Method findMethod(String name,
                         Object[] params)
            throws MethodMap.AmbiguousException
Find a Method using the methodKey provided. Look in the methodMap for an entry. If found, it'll either be a CACHE_MISS, in which case we simply give up, or it'll be a Method, in which case, we return it. If nothing is found, then we must actually go and introspect the method from the MethodMap.

getAccessibleMethods

private static Method[] getAccessibleMethods(Class clazz)
Retrieves public methods for a class. In case the class is not public, retrieves methods with same signature as its public methods from public superclasses and interfaces (if they exist). Basically upcasts every method to the nearest acccessible method.

getAccessibleMethods

private static int getAccessibleMethods(Class clazz,
                                        ClassMap.MethodInfo[] methodInfos,
                                        int upcastCount)
Recursively finds a match for each method, starting with the class, and then searching the superclass and interfaces.
Parameters:
clazz - Class to check
methodInfos - array of methods we are searching to match
upcastCount - current number of methods we have matched
Returns:
count of matched methods

getCachedClass

(package private)  Class getCachedClass()
Returns:
the class object whose methods are cached by this map.

getPublicMethod

private static Method getPublicMethod(Class clazz,
                                      String name,
                                      Class[] paramTypes)
Looks up the method with specified name and signature in the first public superclass or implemented interface of the class.
Parameters:
name - the name of the method
paramTypes - the classes of method parameters

getPublicMethod

public static Method getPublicMethod(Method method)
For a given method, retrieves its publicly accessible counterpart. This method will look for a method with same name and signature declared in a public superclass or implemented interface of this method's declaring class. This counterpart method is publicly callable.
Parameters:
method - a method whose publicly callable counterpart is requested.
Returns:
the publicly callable counterpart method. Note that if the parameter method is itself declared by a public class, this method is an identity function.

makeMethodKey

private String makeMethodKey(Method method)
Make a methodKey for the given method using the concatenation of the name and the types of the method parameters.

makeMethodKey

private static String makeMethodKey(String method,
                                    Object[] params)

populateMethodCache

private void populateMethodCache()
Populate the Map of direct hits. These are taken from all the public methods that our class provides.

Copyright B) 2002 Apache Software Foundation. All Rights Reserved.