ClassMap.java
package org.codehaus.plexus.util.introspection;
/*
* Copyright The Codehaus 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;
/**
* A cache of introspection information for a specific class instance. Keys {@link java.lang.reflect.Method} objects by
* a concatenation of the method name and the names of classes that make up the parameters.
*
* @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
* @author <a href="mailto:bob@werken.com">Bob McWhirter</a>
* @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a>
* @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
*
*/
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 final Class clazz;
/**
* Cache of Methods, or CACHE_MISS, keyed by method name and actual arguments used to find it.
*/
private Map<String, Object> methodCache = new Hashtable<>();
private final MethodMap methodMap = new MethodMap();
/**
* Standard constructor
* @param clazz the Class
*/
public ClassMap(Class clazz) {
this.clazz = clazz;
populateMethodCache();
}
/**
* @return the class object whose methods are cached by this map.
*/
Class getCachedClass() {
return clazz;
}
/**
* <p>Find a Method using the methodKey provided.</p>
*
* <p>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.</p>
*
* <p>If nothing is found, then we must actually go and introspect the method from the MethodMap.</p>
* @param name method name
* @param params method params
* @return the find Method or <code>null</code>
* @throws org.codehaus.plexus.util.introspection.MethodMap.AmbiguousException if ambiguous name
*/
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() {
StringBuffer methodKey;
/*
* 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) {
StringBuilder methodKey = new StringBuilder().append(method);
for (Object param : params) {
Object arg = param;
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 accessible 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 clazz 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
*/
Class[] interfaces = clazz.getInterfaces();
for (Class anInterface : interfaces) {
Method interfaceMethod = getPublicMethod(anInterface, 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;
}
}
}