/*
* 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.lang.reflect.Array;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
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 org.apache.el.lang.ELSupport;
/**
* Utilities for Managing Serialization and Reflection
*
* @author Jacob Hookom [jacob@hookom.net]
*/
public class ReflectionUtil {
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
* @param paramValues the parameter values
* @return the method specified
* @throws MethodNotFoundException
*/
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
@SuppressWarnings("null")
public static Method getMethod(Object base, Object property,
Class<?>[] paramTypes, Object[] paramValues)
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,MatchResult> candidates = new HashMap<Method,MatchResult>();
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;
int assignableMatch = 0;
int coercibleMatch = 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 (isAssignableFrom(paramTypes[j], varType)) {
assignableMatch++;
} else {
if (paramValues == null || j >= paramValues.length) {
noMatch = true;
break;
} else {
if (isCoercibleFrom(paramValues[j], varType)) {
coercibleMatch++;
} else {
noMatch = true;
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 (isAssignableFrom(paramTypes[i], mParamTypes[i])) {
assignableMatch++;
} else {
if (paramValues == null || i >= paramValues.length) {
noMatch = true;
break;
} else {
if (isCoercibleFrom(paramValues[i], mParamTypes[i])) {
coercibleMatch++;
} else {
noMatch = true;
break;
}
}
}
}
if (noMatch) {
continue;
}
// If a method is found where every parameter matches exactly,
// return it
if (exactMatch == paramCount) {
return getMethod(base.getClass(), m);
}
candidates.put(m, new MatchResult(
exactMatch, assignableMatch, coercibleMatch, m.isBridge()));
}
// Look for the method that has the highest number of parameters where
// the type matches exactly
MatchResult bestMatch = new MatchResult(0, 0, 0, false);
Method match = null;
boolean multiple = false;
for (Map.Entry<Method, MatchResult> entry : candidates.entrySet()) {
int cmp = entry.getValue().compareTo(bestMatch);
if (cmp > 0 || match == null) {
bestMatch = entry.getValue();
match = entry.getKey();
multiple = false;
} else if (cmp == 0) {
multiple = true;
}
}
if (multiple) {
if (bestMatch.getExact() == 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 getMethod(base.getClass(), match);
}
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
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;
}
}
if (nonMatchClass == null) {
// Null will always be ambiguous
return null;
}
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
Class<?> superClass = nonMatchClass.getSuperclass();
while (superClass != null) {
for (Method c : candidates) {
if (c.getParameterTypes()[nonMatchIndex].equals(superClass)) {
// Found a match
return c;
}
}
superClass = superClass.getSuperclass();
}
// Treat instances of Number as a special case
Method match = null;
if (Number.class.isAssignableFrom(nonMatchClass)) {
for (Method c : candidates) {
Class<?> candidateType = c.getParameterTypes()[nonMatchIndex];
if (Number.class.isAssignableFrom(candidateType) ||
candidateType.isPrimitive()) {
if (match == null) {
match = c;
} else {
// Match still ambiguous
match = null;
break;
}
}
}
}
return match;
}
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
private static boolean isAssignableFrom(Class<?> src, Class<?> target) {
// src will always be an object
// Short-cut. null is always assignable to an object and in EL null
// can always be coerced to a valid value for a primitive
if (src == null) {
return true;
}
Class<?> targetClass;
if (target.isPrimitive()) {
if (target == Boolean.TYPE) {
targetClass = Boolean.class;
} else if (target == Character.TYPE) {
targetClass = Character.class;
} else if (target == Byte.TYPE) {
targetClass = Byte.class;
} else if (target == Short.TYPE) {
targetClass = Short.class;
} else if (target == Integer.TYPE) {
targetClass = Integer.class;
} else if (target == Long.TYPE) {
targetClass = Long.class;
} else if (target == Float.TYPE) {
targetClass = Float.class;
} else {
targetClass = Double.class;
}
} else {
targetClass = target;
}
return targetClass.isAssignableFrom(src);
}
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
private static boolean isCoercibleFrom(Object src, Class<?> target) {
// TODO: This isn't pretty but it works. Significant refactoring would
// be required to avoid the exception.
try {
ELSupport.coerceToType(src, target);
} catch (ELException e) {
return false;
}
return true;
}
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
private static Method getMethod(Class<?> type, Method m) {
if (m == null || Modifier.isPublic(type.getModifiers())) {
return m;
}
Class<?>[] inf = type.getInterfaces();
Method mp = null;
for (int i = 0; i < inf.length; i++) {
try {
mp = inf[i].getMethod(m.getName(), m.getParameterTypes());
mp = getMethod(mp.getDeclaringClass(), mp);
if (mp != null) {
return mp;
}
} catch (NoSuchMethodException e) {
// Ignore
}
}
Class<?> sup = type.getSuperclass();
if (sup != null) {
try {
mp = sup.getMethod(m.getName(), m.getParameterTypes());
mp = getMethod(mp.getDeclaringClass(), mp);
if (mp != null) {
return mp;
}
} catch (NoSuchMethodException e) {
// Ignore
}
}
return null;
}
private static final String paramString(Class<?>[] types) {
if (types != null) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < types.length; i++) {
if (types[i] == null) {
sb.append("null, ");
} else {
sb.append(types[i].getName()).append(", ");
}
}
if (sb.length() > 2) {
sb.setLength(sb.length() - 2);
}
return sb.toString();
}
return null;
}
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
private static class MatchResult implements Comparable<MatchResult> {
private final int exact;
private final int assignable;
private final int coercible;
private final boolean bridge;
public MatchResult(int exact, int assignable, int coercible, boolean bridge) {
this.exact = exact;
this.assignable = assignable;
this.coercible = coercible;
this.bridge = bridge;
}
public int getExact() {
return exact;
}
public int getAssignable() {
return assignable;
}
public int getCoercible() {
return coercible;
}
public boolean isBridge() {
return bridge;
}
@Override
public int compareTo(MatchResult o) {
if (this.getExact() < o.getExact()) {
return -1;
} else if (this.getExact() > o.getExact()) {
return 1;
} else {
if (this.getAssignable() < o.getAssignable()) {
return -1;
} else if (this.getAssignable() > o.getAssignable()) {
return 1;
} else {
if (this.getCoercible() < o.getCoercible()) {
return -1;
} else if (this.getCoercible() > o.getCoercible()) {
return 1;
} else {
// The nature of bridge methods is such that it actually
// doesn't matter which one we pick as long as we pick
// one. That said, pick the 'right' one (the non-bridge
// one) anyway.
if (o.isBridge() && !this.isBridge()) {
return 1;
} else if (!o.isBridge() && this.isBridge()) {
return -1;
} else {
return 0;
}
}
}
}
}
}
}