/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.el.util;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import javax.el.ELException;
import javax.el.MethodNotFoundException;
import javax.el.PropertyNotFoundException;
import org.apache.el.lang.ELSupport;
/**
* Utilities for Managing Serialization and Reflection
*
* @author Jacob Hookom [jacob@hookom.net]
* @version $Id: ReflectionUtil.java 981816 2010-08-03 10:44:58Z markt $
*/
public class ReflectionUtil {
protected static final String[] EMPTY_STRING = new String[0];
protected static final String[] PRIMITIVE_NAMES = new String[] { "boolean",
"byte", "char", "double", "float", "int", "long", "short", "void" };
protected static final Class<?>[] PRIMITIVES = new Class[] { boolean.class,
byte.class, char.class, double.class, float.class, int.class,
long.class, short.class, Void.TYPE };
private ReflectionUtil() {
super();
}
public static Class<?> forName(String name) throws ClassNotFoundException {
if (null == name || "".equals(name)) {
return null;
}
Class<?> c = forNamePrimitive(name);
if (c == null) {
if (name.endsWith("[]")) {
String nc = name.substring(0, name.length() - 2);
c = Class.forName(nc, true, Thread.currentThread().getContextClassLoader());
c = Array.newInstance(c, 0).getClass();
} else {
c = Class.forName(name, true, Thread.currentThread().getContextClassLoader());
}
}
return c;
}
protected static Class<?> forNamePrimitive(String name) {
if (name.length() <= 8) {
int p = Arrays.binarySearch(PRIMITIVE_NAMES, name);
if (p >= 0) {
return PRIMITIVES[p];
}
}
return null;
}
/**
* Converts an array of Class names to Class types
* @param s
* @throws ClassNotFoundException
*/
public static Class<?>[] toTypeArray(String[] s) throws ClassNotFoundException {
if (s == null)
return null;
Class<?>[] c = new Class[s.length];
for (int i = 0; i < s.length; i++) {
c[i] = forName(s[i]);
}
return c;
}
/**
* Converts an array of Class types to Class names
* @param c
*/
public static String[] toTypeNameArray(Class<?>[] c) {
if (c == null)
return null;
String[] s = new String[c.length];
for (int i = 0; i < c.length; i++) {
s[i] = c[i].getName();
}
return s;
}
/**
* Returns a method based on the criteria
* @param base the object that owns the method
* @param property the name of the method
* @param paramTypes the parameter types to use
* @return the method specified
* @throws MethodNotFoundException
*/
@SuppressWarnings("null")
public static Method getMethod(Object base, Object property,
Class<?>[] paramTypes) throws MethodNotFoundException {
if (base == null || property == null) {
throw new MethodNotFoundException(MessageFactory.get(
"error.method.notfound", base, property,
paramString(paramTypes)));
}
String methodName = (property instanceof String) ? (String) property
: property.toString();
int paramCount;
if (paramTypes == null) {
paramCount = 0;
} else {
paramCount = paramTypes.length;
}
Method[] methods = base.getClass().getMethods();
Map<Method,Integer> candidates = new HashMap<Method,Integer>();
for (Method m : methods) {
if (!m.getName().equals(methodName)) {
// Method name doesn't match
continue;
}
Class<?>[] mParamTypes = m.getParameterTypes();
int mParamCount;
if (mParamTypes == null) {
mParamCount = 0;
} else {
mParamCount = mParamTypes.length;
}
// Check the number of parameters
if (!(paramCount == mParamCount ||
(m.isVarArgs() && paramCount >= mParamCount))) {
// Method has wrong number of parameters
continue;
}
// Check the parameters match
int exactMatch = 0;
boolean noMatch = false;
for (int i = 0; i < mParamCount; i++) {
// Can't be null
if (mParamTypes[i].equals(paramTypes[i])) {
exactMatch++;
} else if (i == (mParamCount - 1) && m.isVarArgs()) {
Class<?> varType = mParamTypes[i].getComponentType();
for (int j = i; j < paramCount; j++) {
if (!varType.isAssignableFrom(paramTypes[j])) {
break;
}
// Don't treat a varArgs match as an exact match, it can
// lead to a varArgs method matching when the result
// should be ambiguous
}
} else if (!mParamTypes[i].isAssignableFrom(paramTypes[i])) {
noMatch = true;
break;
}
}
if (noMatch) {
continue;
}
// If a method is found where every parameter matches exactly,
// return it
if (exactMatch == paramCount) {
return m;
}
candidates.put(m, Integer.valueOf(exactMatch));
}
// Look for the method that has the highest number of parameters where
// the type matches exactly
int bestMatch = 0;
Method match = null;
boolean multiple = false;
for (Map.Entry<Method, Integer> entry : candidates.entrySet()) {
if (entry.getValue().intValue() > bestMatch ||
match == null) {
bestMatch = entry.getValue().intValue();
match = entry.getKey();
multiple = false;
} else if (entry.getValue().intValue() == bestMatch) {
multiple = true;
}
}
if (multiple) {
if (bestMatch == paramCount - 1) {
// Only one parameter is not an exact match - try using the
// super class
match = resolveAmbiguousMethod(candidates.keySet(), paramTypes);
} else {
match = null;
}
if (match == null) {
// If multiple methods have the same matching number of parameters
// the match is ambiguous so throw an exception
throw new MethodNotFoundException(MessageFactory.get(
"error.method.ambiguous", base, property,
paramString(paramTypes)));
}
}
// Handle case where no match at all was found
if (match == null) {
throw new MethodNotFoundException(MessageFactory.get(
"error.method.notfound", base, property,
paramString(paramTypes)));
}
return match;
}
@SuppressWarnings("null")
private static Method resolveAmbiguousMethod(Set<Method> candidates,
Class<?>[] paramTypes) {
// Identify which parameter isn't an exact match
Method m = candidates.iterator().next();
int nonMatchIndex = 0;
Class<?> nonMatchClass = null;
for (int i = 0; i < paramTypes.length; i++) {
if (m.getParameterTypes()[i] != paramTypes[i]) {
nonMatchIndex = i;
nonMatchClass = paramTypes[i];
break;
}
}
for (Method c : candidates) {
if (c.getParameterTypes()[nonMatchIndex] ==
paramTypes[nonMatchIndex]) {
// Methods have different non-matching parameters
// Result is ambiguous
return null;
}
}
// Can't be null
nonMatchClass = nonMatchClass.getSuperclass();
while (nonMatchClass != null) {
for (Method c : candidates) {
if (c.getParameterTypes()[nonMatchIndex].equals(
nonMatchClass)) {
// Found a match
return c;
}
}
nonMatchClass = nonMatchClass.getSuperclass();
}
return null;
}
protected static final String paramString(Class<?>[] types) {
if (types != null) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < types.length; i++) {
sb.append(types[i].getName()).append(", ");
}
if (sb.length() > 2) {
sb.setLength(sb.length() - 2);
}
return sb.toString();
}
return null;
}
public static PropertyDescriptor getPropertyDescriptor(Object base,
Object property) throws ELException, PropertyNotFoundException {
String name = ELSupport.coerceToString(property);
try {
PropertyDescriptor[] desc = Introspector.getBeanInfo(
base.getClass()).getPropertyDescriptors();
for (int i = 0; i < desc.length; i++) {
if (desc[i].getName().equals(name)) {
return desc[i];
}
}
} catch (IntrospectionException ie) {
throw new ELException(ie);
}
throw new PropertyNotFoundException(MessageFactory.get(
"error.property.notfound", base, name));
}
}