ReflectionUtil.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 org.apache.el.util;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedAction;
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;
import org.apache.el.lang.EvaluationContext;
/**
* 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 || name.isEmpty()) {
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, getContextClassLoader());
c = Array.newInstance(c, 0).getClass();
} else {
c = Class.forName(name, true, 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 The array of class names
* @return An array of Class instance where the element at index i in the
* result is an instance of the class with the name at index i in
* the input
* @throws ClassNotFoundException If a class of a given name cannot be found
*/
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 The array of class instances
* @return An array of Class names where the element at index i in the
* result is the name of the class instance at index i in the input
*/
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 ctx the context in which the expression is being evaluated
* @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 If a method cannot be found that matches
* the given criteria
*/
/*
* This class duplicates code in javax.el.Util. When making changes keep
* the code in sync.
*/
@SuppressWarnings("null")
public static Method getMethod(EvaluationContext ctx, 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<>();
for (Method m : methods) {
if (!m.getName().equals(methodName)) {
// Method name doesn't match
continue;
}
Class<?>[] mParamTypes = m.getParameterTypes();
int mParamCount = mParamTypes.length;
// Check the number of parameters
// Multiple tests to improve readability
if (!m.isVarArgs() && paramCount != mParamCount) {
// Method has wrong number of parameters
continue;
}
if (m.isVarArgs() && paramCount < mParamCount -1) {
// Method has wrong number of parameters
continue;
}
if (m.isVarArgs() && paramCount == mParamCount && paramValues != null &&
paramValues.length > paramCount && !paramTypes[mParamCount -1].isArray()) {
// Method arguments don't match
continue;
}
if (m.isVarArgs() && paramCount > mParamCount && paramValues != null &&
paramValues.length != paramCount) {
// Might match a different varargs method
continue;
}
if (!m.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 (m.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(ctx, 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(ctx, 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) {
Method result = getMethod(base.getClass(), base, m);
if (result == null) {
throw new MethodNotFoundException(MessageFactory.get(
"error.method.notfound", base, property,
paramString(paramTypes)));
}
return result;
}
candidates.put(m, new MatchResult(
m.isVarArgs(), exactMatch, assignableMatch, coercibleMatch, varArgsMatch, m.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);
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.getExactCount() == 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)));
}
Method result = getMethod(base.getClass(), base, match);
if (result == null) {
throw new MethodNotFoundException(MessageFactory.get(
"error.method.notfound", base, property,
paramString(paramTypes)));
}
return result;
}
/*
* 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(EvaluationContext ctx, Object src, Class<?> target) {
// TODO: This isn't pretty but it works. Significant refactoring would
// be required to avoid the exception.
try {
ELSupport.coerceToType(ctx, 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, Object base, Method m) {
JreCompat jreCompat = JreCompat.getInstance();
if (m == null ||
(Modifier.isPublic(type.getModifiers()) &&
(Modifier.isStatic(m.getModifiers()) && jreCompat.canAccess(null, m)
|| jreCompat.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;
}
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;
}
private static ClassLoader getContextClassLoader() {
ClassLoader tccl;
if (System.getSecurityManager() != null) {
PrivilegedAction<ClassLoader> pa = new PrivilegedGetTccl();
tccl = AccessController.doPrivileged(pa);
} else {
tccl = Thread.currentThread().getContextClassLoader();
}
return tccl;
}
private static class PrivilegedGetTccl implements PrivilegedAction<ClassLoader> {
@Override
public ClassLoader run() {
return Thread.currentThread().getContextClassLoader();
}
}
/*
* 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 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 getCoercible() {
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.getCoercible(), o.getCoercible());
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).getCoercible() == this.getCoercible() &&
((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;
}
}
}