org.codehaus.plexus.interpolation.reflection.ClassMap Maven / Gradle / Ivy
package org.codehaus.plexus.interpolation.reflection;
/* ====================================================================
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* ====================================================================
*/
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Hashtable;
import java.util.Map;
/**
* NOTE: This class was copied from plexus-utils, to allow this library
* to stand completely self-contained.
* A cache of introspection information for a specific class instance.
* Keys {@link Method} objects by a concatenation of the
* method name and the names of classes that make up the parameters.
*
* @author Jason van Zyl
* @author Bob McWhirter
* @author Attila Szegedi
* @author Geir Magnusson Jr.
*/
public class ClassMap
{
private static final class CacheMiss
{
}
private static final CacheMiss CACHE_MISS = new CacheMiss();
private static final Object OBJECT = new Object();
/**
* Class passed into the constructor used to as
* the basis for the Method map.
*/
private Class clazz;
/**
* Cache of Methods, or CACHE_MISS, keyed by method
* name and actual arguments used to find it.
*/
private Map methodCache = new Hashtable();
private MethodMap methodMap = new MethodMap();
/**
* Standard constructor
* @param clazz The class to be analyzed.
*/
public ClassMap( Class clazz )
{
this.clazz = clazz;
populateMethodCache();
}
/**
* @return the class object whose methods are cached by this map.
*/
Class getCachedClass()
{
return clazz;
}
/**
* 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.
* @param name name of the method.
* @param params The parameters for the method.
* @return {@link Method}.
* @throws MethodMap.AmbiguousException in case of an error.
*/
public Method findMethod( String name, Object[] params )
throws MethodMap.AmbiguousException
{
String methodKey = makeMethodKey( name, params );
Object cacheEntry = methodCache.get( methodKey );
if ( cacheEntry == CACHE_MISS )
{
return null;
}
if ( cacheEntry == null )
{
try
{
cacheEntry = methodMap.find( name, params );
}
catch ( MethodMap.AmbiguousException ae )
{
/*
* that's a miss :)
*/
methodCache.put( methodKey, CACHE_MISS );
throw ae;
}
if ( cacheEntry == null )
{
methodCache.put( methodKey, CACHE_MISS );
}
else
{
methodCache.put( methodKey, cacheEntry );
}
}
// Yes, this might just be null.
return (Method) cacheEntry;
}
/**
* Populate the Map of direct hits. These
* are taken from all the public methods
* that our class provides.
*/
private void populateMethodCache()
{
/*
* get all publicly accessible methods
*/
Method[] methods = getAccessibleMethods( clazz );
/*
* map and cache them
*/
for ( Method method : methods )
{
/*
* now get the 'public method', the method declared by a
* public interface or class. (because the actual implementing
* class may be a facade...
*/
Method publicMethod = getPublicMethod( method );
/*
* it is entirely possible that there is no public method for
* the methods of this class (i.e. in the facade, a method
* that isn't on any of the interfaces or superclass
* in which case, ignore it. Otherwise, map and cache
*/
if ( publicMethod != null )
{
methodMap.add( publicMethod );
methodCache.put( makeMethodKey( publicMethod ), publicMethod );
}
}
}
/**
* Make a methodKey for the given method using
* the concatenation of the name and the
* types of the method parameters.
*/
private String makeMethodKey( Method method )
{
Class[] parameterTypes = method.getParameterTypes();
StringBuilder methodKey = new StringBuilder( method.getName() );
for ( Class parameterType : parameterTypes )
{
/*
* If the argument type is primitive then we want
* to convert our primitive type signature to the
* corresponding Object type so introspection for
* methods with primitive types will work correctly.
*/
if ( parameterType.isPrimitive() )
{
if ( parameterType.equals( Boolean.TYPE ) )
{
methodKey.append( "java.lang.Boolean" );
}
else if ( parameterType.equals( Byte.TYPE ) )
{
methodKey.append( "java.lang.Byte" );
}
else if ( parameterType.equals( Character.TYPE ) )
{
methodKey.append( "java.lang.Character" );
}
else if ( parameterType.equals( Double.TYPE ) )
{
methodKey.append( "java.lang.Double" );
}
else if ( parameterType.equals( Float.TYPE ) )
{
methodKey.append( "java.lang.Float" );
}
else if ( parameterType.equals( Integer.TYPE ) )
{
methodKey.append( "java.lang.Integer" );
}
else if ( parameterType.equals( Long.TYPE ) )
{
methodKey.append( "java.lang.Long" );
}
else if ( parameterType.equals( Short.TYPE ) )
{
methodKey.append( "java.lang.Short" );
}
}
else
{
methodKey.append( parameterType.getName() );
}
}
return methodKey.toString();
}
private static String makeMethodKey( String method, Object[] params )
{
if (params.length == 0)
{
return method;
}
StringBuilder methodKey = new StringBuilder().append( method );
for ( Object arg : params )
{
if ( arg == null )
{
arg = OBJECT;
}
methodKey.append( arg.getClass().getName() );
}
return methodKey.toString();
}
/**
* 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.
*/
private static Method[] getAccessibleMethods( Class clazz )
{
Method[] methods = clazz.getMethods();
/*
* Short circuit for the (hopefully) majority of cases where the
* clazz is public
*/
if ( Modifier.isPublic( clazz.getModifiers() ) )
{
return methods;
}
/*
* No luck - the class is not public, so we're going the longer way.
*/
MethodInfo[] methodInfos = new MethodInfo[methods.length];
for ( int i = methods.length; i-- > 0; )
{
methodInfos[i] = new MethodInfo( methods[i] );
}
int upcastCount = getAccessibleMethods( clazz, methodInfos, 0 );
/*
* Reallocate array in case some method had no accessible counterpart.
*/
if ( upcastCount < methods.length )
{
methods = new Method[upcastCount];
}
int j = 0;
for ( MethodInfo methodInfo : methodInfos )
{
if ( methodInfo.upcast )
{
methods[j++] = methodInfo.method;
}
}
return methods;
}
/**
* Recursively finds a match for each method, starting with the class, and then
* searching the superclass and interfaces.
*
* @param clazz Class to check
* @param methodInfos array of methods we are searching to match
* @param upcastCount current number of methods we have matched
* @return count of matched methods
*/
private static int getAccessibleMethods( Class clazz, MethodInfo[] methodInfos, int upcastCount )
{
int l = methodInfos.length;
/*
* if this class is public, then check each of the currently
* 'non-upcasted' methods to see if we have a match
*/
if ( Modifier.isPublic( clazz.getModifiers() ) )
{
for ( int i = 0; i < l && upcastCount < l; ++i )
{
try
{
MethodInfo methodInfo = methodInfos[i];
if ( !methodInfo.upcast )
{
methodInfo.tryUpcasting( clazz );
upcastCount++;
}
}
catch ( NoSuchMethodException e )
{
/*
* Intentionally ignored - it means
* it wasn't found in the current class
*/
}
}
/*
* Short circuit if all methods were upcast
*/
if ( upcastCount == l )
{
return upcastCount;
}
}
/*
* Examine superclass
*/
Class superclazz = clazz.getSuperclass();
if ( superclazz != null )
{
upcastCount = getAccessibleMethods( superclazz, methodInfos, upcastCount );
/*
* Short circuit if all methods were upcast
*/
if ( upcastCount == l )
{
return upcastCount;
}
}
/*
* Examine interfaces. Note we do it even if superclazz == null.
* This is redundant as currently java.lang.Object does not implement
* any interfaces, however nothing guarantees it will not in future.
*/
Class[] interfaces = clazz.getInterfaces();
for ( int i = interfaces.length; i-- > 0; )
{
upcastCount = getAccessibleMethods( interfaces[i], methodInfos, upcastCount );
/*
* Short circuit if all methods were upcast
*/
if ( upcastCount == l )
{
return upcastCount;
}
}
return upcastCount;
}
/**
* 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.
*
* @param method a method whose publicly callable counterpart is requested.
* @return the publicly callable counterpart method. Note that if the parameter
* method is itself declared by a public class, this method is an identity
* function.
*/
public static Method getPublicMethod( Method method )
{
Class clazz = method.getDeclaringClass();
/*
* Short circuit for (hopefully the majority of) cases where the declaring
* class is public.
*/
if ( ( clazz.getModifiers() & Modifier.PUBLIC ) != 0 )
{
return method;
}
return getPublicMethod( clazz, method.getName(), method.getParameterTypes() );
}
/**
* Looks up the method with specified name and signature in the first public
* superclass or implemented interface of the class.
*
* @param class the class whose method is sought
* @param name the name of the method
* @param paramTypes the classes of method parameters
*/
private static Method getPublicMethod( Class clazz, String name, Class[] paramTypes )
{
/*
* if this class is public, then try to get it
*/
if ( ( clazz.getModifiers() & Modifier.PUBLIC ) != 0 )
{
try
{
return clazz.getMethod( name, paramTypes );
}
catch ( NoSuchMethodException e )
{
/*
* If the class does not have the method, then neither its
* superclass nor any of its interfaces has it so quickly return
* null.
*/
return null;
}
}
/*
* try the superclass
*/
Class superclazz = clazz.getSuperclass();
if ( superclazz != null )
{
Method superclazzMethod = getPublicMethod( superclazz, name, paramTypes );
if ( superclazzMethod != null )
{
return superclazzMethod;
}
}
/*
* and interfaces
*/
for ( Class interface_ : clazz.getInterfaces() )
{
Method interfaceMethod = getPublicMethod( interface_, name, paramTypes );
if ( interfaceMethod != null )
{
return interfaceMethod;
}
}
return null;
}
/**
* Used for the iterative discovery process for public methods.
*/
private static final class MethodInfo
{
Method method;
String name;
Class[] parameterTypes;
boolean upcast;
MethodInfo( Method method )
{
this.method = null;
name = method.getName();
parameterTypes = method.getParameterTypes();
upcast = false;
}
void tryUpcasting( Class clazz )
throws NoSuchMethodException
{
method = clazz.getMethod( name, parameterTypes );
name = null;
parameterTypes = null;
upcast = true;
}
}
}