Util.java
/*
* 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 jakarta.el;
import java.lang.ref.WeakReference;
import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
class Util {
private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
private static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
/**
* Checks whether the supplied Throwable is one that needs to be rethrown and swallows all others.
*
* @param t the Throwable to check
*/
static void handleThrowable(Throwable t) {
if (t instanceof VirtualMachineError) {
throw (VirtualMachineError) t;
}
// All other instances of Throwable will be silently swallowed
}
static String message(ELContext context, String name, Object... props) {
Locale locale = null;
if (context != null) {
locale = context.getLocale();
}
if (locale == null) {
locale = Locale.getDefault();
if (locale == null) {
return "";
}
}
ResourceBundle bundle = ResourceBundle.getBundle("jakarta.el.LocalStrings", locale);
try {
String template = bundle.getString(name);
if (props != null) {
template = MessageFormat.format(template, props);
}
return template;
} catch (MissingResourceException e) {
return "Missing Resource: '" + name + "' for Locale " + locale.getDisplayName();
}
}
private static final CacheValue nullTcclFactory = new CacheValue();
private static final Map<CacheKey,CacheValue> factoryCache = new ConcurrentHashMap<>();
/**
* Provides a per class loader cache of ExpressionFactory instances without pinning any in memory as that could
* trigger a memory leak.
*/
static ExpressionFactory getExpressionFactory() {
ClassLoader tccl = Thread.currentThread().getContextClassLoader();
CacheValue cacheValue = null;
ExpressionFactory factory = null;
if (tccl == null) {
cacheValue = nullTcclFactory;
} else {
CacheKey key = new CacheKey(tccl);
cacheValue = factoryCache.get(key);
if (cacheValue == null) {
CacheValue newCacheValue = new CacheValue();
cacheValue = factoryCache.putIfAbsent(key, newCacheValue);
if (cacheValue == null) {
cacheValue = newCacheValue;
}
}
}
final Lock readLock = cacheValue.getLock().readLock();
readLock.lock();
try {
factory = cacheValue.getExpressionFactory();
} finally {
readLock.unlock();
}
if (factory == null) {
final Lock writeLock = cacheValue.getLock().writeLock();
writeLock.lock();
try {
factory = cacheValue.getExpressionFactory();
if (factory == null) {
factory = ExpressionFactory.newInstance();
cacheValue.setExpressionFactory(factory);
}
} finally {
writeLock.unlock();
}
}
return factory;
}
/**
* Key used to cache default ExpressionFactory information per class loader. The class loader reference is never
* {@code null}, because {@code null} tccl is handled separately.
*/
private static class CacheKey {
private final int hash;
private final WeakReference<ClassLoader> ref;
CacheKey(ClassLoader key) {
hash = key.hashCode();
ref = new WeakReference<>(key);
}
@Override
public int hashCode() {
return hash;
}
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof CacheKey)) {
return false;
}
ClassLoader thisKey = ref.get();
if (thisKey == null) {
return false;
}
return thisKey == ((CacheKey) obj).ref.get();
}
}
private static class CacheValue {
private final ReadWriteLock lock = new ReentrantReadWriteLock();
private WeakReference<ExpressionFactory> ref;
CacheValue() {
}
public ReadWriteLock getLock() {
return lock;
}
public ExpressionFactory getExpressionFactory() {
return ref != null ? ref.get() : null;
}
public void setExpressionFactory(ExpressionFactory factory) {
ref = new WeakReference<>(factory);
}
}
/*
* This method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
static Method findMethod(ELContext context, Class<?> clazz, Object base, String methodName, Class<?>[] paramTypes,
Object[] paramValues) {
if (clazz == null || methodName == null) {
throw new MethodNotFoundException(
message(null, "util.method.notfound", clazz, methodName, paramString(paramTypes)));
}
if (paramTypes == null) {
paramTypes = getTypesFromValues(paramValues);
}
// Fast path: when no arguments exist, there can only be one matching method and no need for coercion.
if (paramTypes.length == 0) {
try {
Method method = clazz.getMethod(methodName, paramTypes);
return getMethod(clazz, base, method);
} catch (NoSuchMethodException | SecurityException e) {
// Fall through to broader, slower logic
}
}
Method[] methods = clazz.getMethods();
List<Wrapper<Method>> wrappers = Wrapper.wrap(methods, methodName);
Wrapper<Method> result = findWrapper(context, clazz, wrappers, methodName, paramTypes, paramValues);
return getMethod(clazz, base, result.unWrap());
}
/*
* This method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
@SuppressWarnings("null")
private static <T> Wrapper<T> findWrapper(ELContext context, Class<?> clazz, List<Wrapper<T>> wrappers, String name,
Class<?>[] paramTypes, Object[] paramValues) {
Map<Wrapper<T>,MatchResult> candidates = new HashMap<>();
int paramCount = paramTypes.length;
for (Wrapper<T> w : wrappers) {
Class<?>[] mParamTypes = w.getParameterTypes();
int mParamCount;
if (mParamTypes == null) {
mParamCount = 0;
} else {
mParamCount = mParamTypes.length;
}
// Check the number of parameters
// Multiple tests to improve readability
if (!w.isVarArgs() && paramCount != mParamCount) {
// Method has wrong number of parameters
continue;
}
if (w.isVarArgs() && paramCount < mParamCount - 1) {
// Method has wrong number of parameters
continue;
}
if (w.isVarArgs() && paramCount == mParamCount && paramValues != null && paramValues.length > paramCount &&
!paramTypes[mParamCount - 1].isArray()) {
// Method arguments don't match
continue;
}
if (w.isVarArgs() && paramCount > mParamCount && paramValues != null && paramValues.length != paramCount) {
// Might match a different varargs method
continue;
}
if (!w.isVarArgs() && paramValues != null && paramCount != paramValues.length) {
// Might match a different varargs method
continue;
}
// Check the parameters match
int exactMatch = 0;
int assignableMatch = 0;
int coercibleMatch = 0;
int varArgsMatch = 0;
boolean noMatch = false;
for (int i = 0; i < mParamCount; i++) {
// Can't be null
if (w.isVarArgs() && i == (mParamCount - 1)) {
if (i == paramCount || (paramValues != null && paramValues.length == i)) {
// Var args defined but nothing is passed as varargs
// Use MAX_VALUE so this matches only if nothing else does
varArgsMatch = Integer.MAX_VALUE;
break;
}
Class<?> varType = mParamTypes[i].getComponentType();
for (int j = i; j < paramCount; j++) {
if (isAssignableFrom(paramTypes[j], varType)) {
assignableMatch++;
varArgsMatch++;
} else {
if (paramValues == null) {
noMatch = true;
break;
} else {
if (isCoercibleFrom(context, paramValues[j], varType)) {
coercibleMatch++;
varArgsMatch++;
} 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 (mParamTypes[i].equals(paramTypes[i])) {
exactMatch++;
} else if (paramTypes[i] != null && isAssignableFrom(paramTypes[i], mParamTypes[i])) {
assignableMatch++;
} else {
if (paramValues == null) {
noMatch = true;
break;
} else {
if (isCoercibleFrom(context, paramValues[i], mParamTypes[i])) {
coercibleMatch++;
} else {
noMatch = true;
break;
}
}
}
}
}
if (noMatch) {
continue;
}
// If a method is found where every parameter matches exactly,
// and no vars args are present, return it
if (exactMatch == paramCount && varArgsMatch == 0) {
return w;
}
candidates.put(w, new MatchResult(w.isVarArgs(), exactMatch, assignableMatch, coercibleMatch, varArgsMatch,
w.isBridge()));
}
// Look for the method that has the highest number of parameters where
// the type matches exactly
MatchResult bestMatch = new MatchResult(true, 0, 0, 0, 0, true);
Wrapper<T> match = null;
boolean multiple = false;
for (Map.Entry<Wrapper<T>,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.getExactCount() == paramCount - 1) {
// Only one parameter is not an exact match - try using the
// super class
match = resolveAmbiguousWrapper(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(
message(null, "util.method.ambiguous", clazz, name, paramString(paramTypes)));
}
}
// Handle case where no match at all was found
if (match == null) {
throw new MethodNotFoundException(
message(null, "util.method.notfound", clazz, name, paramString(paramTypes)));
}
return match;
}
private static String paramString(Class<?>[] types) {
if (types != null) {
StringBuilder sb = new StringBuilder();
for (Class<?> type : types) {
if (type == null) {
sb.append("null, ");
} else {
sb.append(type.getName()).append(", ");
}
}
if (sb.length() > 2) {
sb.setLength(sb.length() - 2);
}
return sb.toString();
}
return null;
}
/*
* This method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
private static <T> Wrapper<T> resolveAmbiguousWrapper(Set<Wrapper<T>> candidates, Class<?>[] paramTypes) {
// Identify which parameter isn't an exact match
Wrapper<T> w = candidates.iterator().next();
int nonMatchIndex = 0;
Class<?> nonMatchClass = null;
for (int i = 0; i < paramTypes.length; i++) {
if (w.getParameterTypes()[i] != paramTypes[i]) {
nonMatchIndex = i;
nonMatchClass = paramTypes[i];
break;
}
}
if (nonMatchClass == null) {
// Null will always be ambiguous
return null;
}
for (Wrapper<T> 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 (Wrapper<T> c : candidates) {
if (c.getParameterTypes()[nonMatchIndex].equals(superClass)) {
// Found a match
return c;
}
}
superClass = superClass.getSuperclass();
}
// Treat instances of Number as a special case
Wrapper<T> match = null;
if (Number.class.isAssignableFrom(nonMatchClass)) {
for (Wrapper<T> 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 method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
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 method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
private static boolean isCoercibleFrom(ELContext context, Object src, Class<?> target) {
/*
* TODO: This isn't pretty but it works. Significant refactoring would be required to avoid the exception. See
* also OptionalELResolver.convertToType().
*/
try {
context.convertToType(src, target);
} catch (ELException e) {
return false;
}
return true;
}
private static Class<?>[] getTypesFromValues(Object[] values) {
if (values == null) {
return EMPTY_CLASS_ARRAY;
}
Class<?> result[] = new Class<?>[values.length];
for (int i = 0; i < values.length; i++) {
if (values[i] == null) {
result[i] = null;
} else {
result[i] = values[i].getClass();
}
}
return result;
}
/*
* This method duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
static Method getMethod(Class<?> type, Object base, Method m) {
if (m == null || (Modifier.isPublic(type.getModifiers()) &&
(Modifier.isStatic(m.getModifiers()) && canAccess(null, m) || canAccess(base, m)))) {
return m;
}
Class<?>[] interfaces = type.getInterfaces();
Method mp = null;
for (Class<?> iface : interfaces) {
try {
mp = iface.getMethod(m.getName(), m.getParameterTypes());
mp = getMethod(mp.getDeclaringClass(), base, 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(), base, mp);
if (mp != null) {
return mp;
}
} catch (NoSuchMethodException e) {
// Ignore
}
}
return null;
}
static Constructor<?> findConstructor(ELContext context, Class<?> clazz, Class<?>[] paramTypes,
Object[] paramValues) {
String methodName = "<init>";
if (clazz == null) {
throw new MethodNotFoundException(
message(null, "util.method.notfound", null, methodName, paramString(paramTypes)));
}
if (paramTypes == null) {
paramTypes = getTypesFromValues(paramValues);
}
Constructor<?>[] constructors = clazz.getConstructors();
List<Wrapper<Constructor<?>>> wrappers = Wrapper.wrap(constructors);
Wrapper<Constructor<?>> wrapper = findWrapper(context, clazz, wrappers, methodName, paramTypes, paramValues);
Constructor<?> constructor = wrapper.unWrap();
if (!Modifier.isPublic(clazz.getModifiers()) || !canAccess(null, constructor)) {
throw new MethodNotFoundException(
message(null, "util.method.notfound", clazz, methodName, paramString(paramTypes)));
}
return constructor;
}
static boolean canAccess(Object base, AccessibleObject accessibleObject) {
try {
return accessibleObject.canAccess(base);
} catch (IllegalArgumentException iae) {
return false;
}
}
static Object[] buildParameters(ELContext context, Class<?>[] parameterTypes, boolean isVarArgs, Object[] params) {
Object[] parameters = null;
if (parameterTypes.length > 0) {
parameters = new Object[parameterTypes.length];
int paramCount;
if (params == null) {
params = EMPTY_OBJECT_ARRAY;
}
paramCount = params.length;
if (isVarArgs) {
int varArgIndex = parameterTypes.length - 1;
// First argCount-1 parameters are standard
for (int i = 0; (i < varArgIndex); i++) {
parameters[i] = context.convertToType(params[i], parameterTypes[i]);
}
// Last parameter is the varargs
Class<?> varArgClass = parameterTypes[varArgIndex].getComponentType();
final Object varargs = Array.newInstance(varArgClass, (paramCount - varArgIndex));
for (int i = (varArgIndex); i < paramCount; i++) {
Array.set(varargs, i - varArgIndex, context.convertToType(params[i], varArgClass));
}
parameters[varArgIndex] = varargs;
} else {
parameters = new Object[parameterTypes.length];
for (int i = 0; i < parameterTypes.length; i++) {
parameters[i] = context.convertToType(params[i], parameterTypes[i]);
}
}
}
return parameters;
}
private abstract static class Wrapper<T> {
public static List<Wrapper<Method>> wrap(Method[] methods, String name) {
List<Wrapper<Method>> result = new ArrayList<>();
for (Method method : methods) {
if (method.getName().equals(name)) {
result.add(new MethodWrapper(method));
}
}
return result;
}
public static List<Wrapper<Constructor<?>>> wrap(Constructor<?>[] constructors) {
List<Wrapper<Constructor<?>>> result = new ArrayList<>();
for (Constructor<?> constructor : constructors) {
result.add(new ConstructorWrapper(constructor));
}
return result;
}
public abstract T unWrap();
public abstract Class<?>[] getParameterTypes();
public abstract boolean isVarArgs();
public abstract boolean isBridge();
}
private static class MethodWrapper extends Wrapper<Method> {
private final Method m;
MethodWrapper(Method m) {
this.m = m;
}
@Override
public Method unWrap() {
return m;
}
@Override
public Class<?>[] getParameterTypes() {
return m.getParameterTypes();
}
@Override
public boolean isVarArgs() {
return m.isVarArgs();
}
@Override
public boolean isBridge() {
return m.isBridge();
}
}
private static class ConstructorWrapper extends Wrapper<Constructor<?>> {
private final Constructor<?> c;
ConstructorWrapper(Constructor<?> c) {
this.c = c;
}
@Override
public Constructor<?> unWrap() {
return c;
}
@Override
public Class<?>[] getParameterTypes() {
return c.getParameterTypes();
}
@Override
public boolean isVarArgs() {
return c.isVarArgs();
}
@Override
public boolean isBridge() {
return false;
}
}
/*
* This class duplicates code in org.apache.el.util.ReflectionUtil. When making changes keep the code in sync.
*/
private static class MatchResult implements Comparable<MatchResult> {
private final boolean varArgs;
private final int exactCount;
private final int assignableCount;
private final int coercibleCount;
private final int varArgsCount;
private final boolean bridge;
MatchResult(boolean varArgs, int exactCount, int assignableCount, int coercibleCount, int varArgsCount,
boolean bridge) {
this.varArgs = varArgs;
this.exactCount = exactCount;
this.assignableCount = assignableCount;
this.coercibleCount = coercibleCount;
this.varArgsCount = varArgsCount;
this.bridge = bridge;
}
public boolean isVarArgs() {
return varArgs;
}
public int getExactCount() {
return exactCount;
}
public int getAssignableCount() {
return assignableCount;
}
public int getCoercibleCount() {
return coercibleCount;
}
public int getVarArgsCount() {
return varArgsCount;
}
public boolean isBridge() {
return bridge;
}
@Override
public int compareTo(MatchResult o) {
// Non-varArgs always beats varArgs
int cmp = Boolean.compare(o.isVarArgs(), this.isVarArgs());
if (cmp == 0) {
cmp = Integer.compare(this.getExactCount(), o.getExactCount());
if (cmp == 0) {
cmp = Integer.compare(this.getAssignableCount(), o.getAssignableCount());
if (cmp == 0) {
cmp = Integer.compare(this.getCoercibleCount(), o.getCoercibleCount());
if (cmp == 0) {
// Fewer var args matches are better
cmp = Integer.compare(o.getVarArgsCount(), this.getVarArgsCount());
if (cmp == 0) {
// 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.
cmp = Boolean.compare(o.isBridge(), this.isBridge());
}
}
}
}
}
return cmp;
}
@Override
public boolean equals(Object o) {
return o == this || (null != o && this.getClass().equals(o.getClass()) &&
((MatchResult) o).getExactCount() == this.getExactCount() &&
((MatchResult) o).getAssignableCount() == this.getAssignableCount() &&
((MatchResult) o).getCoercibleCount() == this.getCoercibleCount() &&
((MatchResult) o).getVarArgsCount() == this.getVarArgsCount() &&
((MatchResult) o).isVarArgs() == this.isVarArgs() &&
((MatchResult) o).isBridge() == this.isBridge());
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + assignableCount;
result = prime * result + (bridge ? 1231 : 1237);
result = prime * result + coercibleCount;
result = prime * result + exactCount;
result = prime * result + (varArgs ? 1231 : 1237);
result = prime * result + varArgsCount;
return result;
}
}
}