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ReflectiveMethodResolver reliably prefers direct matches over vararg methods

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Issue: SPR-12803
This commit is contained in:
Juergen Hoeller
2015-03-11 18:58:39 +01:00
parent 474862a7c9
commit e7cc19537d
3 changed files with 96 additions and 49 deletions
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76
spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2002-2013 the original author or authors.
* Copyright 2002-2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -42,13 +42,14 @@ import org.springframework.util.MethodInvoker;
public class ReflectionHelper {
/**
* Compare argument arrays and return information about whether they match. A supplied
* type converter and conversionAllowed flag allow for matches to take into account
* that a type may be transformed into a different type by the converter.
* @param expectedArgTypes the array of types the method/constructor is expecting
* @param suppliedArgTypes the array of types that are being supplied at the point of invocation
* Compare argument arrays and return information about whether they match.
* A supplied type converter and conversionAllowed flag allow for matches to take
* into account that a type may be transformed into a different type by the converter.
* @param expectedArgTypes the types the method/constructor is expecting
* @param suppliedArgTypes the types that are being supplied at the point of invocation
* @param typeConverter a registered type converter
* @return a MatchInfo object indicating what kind of match it was or null if it was not a match
* @return a MatchInfo object indicating what kind of match it was,
* or {@code null} if it was not a match
*/
static ArgumentsMatchInfo compareArguments(
List<TypeDescriptor> expectedArgTypes, List<TypeDescriptor> suppliedArgTypes, TypeConverter typeConverter) {
@@ -111,7 +112,7 @@ public class ReflectionHelper {
int result = 0;
for (int i = 0; i < paramTypes.size(); i++) {
TypeDescriptor paramType = paramTypes.get(i);
TypeDescriptor argType = argTypes.get(i);
TypeDescriptor argType = (i < argTypes.size() ? argTypes.get(i) : null);
if (argType == null) {
if (paramType.isPrimitive()) {
return Integer.MAX_VALUE;
@@ -148,13 +149,15 @@ public class ReflectionHelper {
}
/**
* Compare argument arrays and return information about whether they match. A supplied type converter and
* conversionAllowed flag allow for matches to take into account that a type may be transformed into a different
* type by the converter. This variant of compareArguments also allows for a varargs match.
* @param expectedArgTypes the array of types the method/constructor is expecting
* @param suppliedArgTypes the array of types that are being supplied at the point of invocation
* Compare argument arrays and return information about whether they match.
* A supplied type converter and conversionAllowed flag allow for matches to
* take into account that a type may be transformed into a different type by the
* converter. This variant of compareArguments also allows for a varargs match.
* @param expectedArgTypes the types the method/constructor is expecting
* @param suppliedArgTypes the types that are being supplied at the point of invocation
* @param typeConverter a registered type converter
* @return a MatchInfo object indicating what kind of match it was or null if it was not a match
* @return a MatchInfo object indicating what kind of match it was,
* or {@code null} if it was not a match
*/
static ArgumentsMatchInfo compareArgumentsVarargs(
List<TypeDescriptor> expectedArgTypes, List<TypeDescriptor> suppliedArgTypes, TypeConverter typeConverter) {
@@ -264,14 +267,15 @@ public class ReflectionHelper {
}
/**
* Takes an input set of argument values and, following the positions specified in the int array,
* it converts them to the types specified as the required parameter types. The arguments are
* converted 'in-place' in the input array.
* Takes an input set of argument values and converts them to the types specified as the
* required parameter types. The arguments are converted 'in-place' in the input array.
* @param converter the type converter to use for attempting conversions
* @param arguments the actual arguments that need conversion
* @param methodOrCtor the target Method or Constructor
* @param argumentsRequiringConversion details which of the input arguments for sure need conversion
* @param argumentsRequiringConversion details which of the input arguments need conversion
* @param varargsPosition the known position of the varargs argument, if any
* ({@code null} if not varargs)
* @return {@code true} if some kind of conversion occurred on an argument
* @throws EvaluationException if a problem occurs during conversion
*/
static void convertArguments(TypeConverter converter, Object[] arguments, Object methodOrCtor,
@@ -285,6 +289,7 @@ public class ReflectionHelper {
}
}
else {
// Convert everything up to the varargs position
for (int i = 0; i < varargsPosition; i++) {
TypeDescriptor targetType = new TypeDescriptor(MethodParameter.forMethodOrConstructor(methodOrCtor, i));
Object argument = arguments[i];
@@ -292,11 +297,13 @@ public class ReflectionHelper {
}
MethodParameter methodParam = MethodParameter.forMethodOrConstructor(methodOrCtor, varargsPosition);
if (varargsPosition == arguments.length - 1) {
// If the target is varargs and there is just one more argument then convert it here
TypeDescriptor targetType = new TypeDescriptor(methodParam);
Object argument = arguments[varargsPosition];
arguments[varargsPosition] = converter.convertValue(argument, TypeDescriptor.forObject(argument), targetType);
}
else {
// Convert remaining arguments to the varargs element type
TypeDescriptor targetType = TypeDescriptor.nested(methodParam, 1);
for (int i = varargsPosition; i < arguments.length; i++) {
Object argument = arguments[i];
@@ -307,12 +314,14 @@ public class ReflectionHelper {
}
/**
* Convert a supplied set of arguments into the requested types. If the parameterTypes are related to
* a varargs method then the final entry in the parameterTypes array is going to be an array itself whose
* component type should be used as the conversion target for extraneous arguments. (For example, if the
* parameterTypes are {Integer, String[]} and the input arguments are {Integer, boolean, float} then both
* the boolean and float must be converted to strings). This method does not repackage the arguments
* into a form suitable for the varargs invocation
* Convert a supplied set of arguments into the requested types.
* If the parameterTypes are related to a varargs method, then the final entry
* in the parameterTypes array is going to be an array itself whose component type
* should be used as the conversion target for extraneous arguments. (For example,
* if the parameterTypes are {@code {Integer, String[]}} and the input arguments
* are {@code {Integer, boolean, float}} then both the boolean and float must be
* converted to Strings). This method does not repackage the arguments into a
* form suitable for the varargs invocation.
* @param converter the converter to use for type conversions
* @param arguments the arguments to convert to the requested parameter types
* @param method the target Method
@@ -359,10 +368,10 @@ public class ReflectionHelper {
}
/**
* Package up the arguments so that they correctly match what is expected in parameterTypes. For example, if
* parameterTypes is (int, String[]) because the second parameter was declared String... then if arguments is
* [1,"a","b"] then it must be repackaged as [1,new String[]{"a","b"}] in order to match the expected
* parameterTypes.
* Package up the arguments so that they correctly match what is expected in parameterTypes.
* For example, if parameterTypes is {@code (int, String[])} because the second parameter
* was declared {@code String...}, then if arguments is {@code [1,"a","b"]} then it must be
* repackaged as {@code [1,new String[]{"a","b"}]} in order to match the expected types.
* @param requiredParameterTypes the types of the parameters for the invocation
* @param args the arguments to be setup ready for the invocation
* @return a repackaged array of arguments where any varargs setup has been done
@@ -372,7 +381,7 @@ public class ReflectionHelper {
int parameterCount = requiredParameterTypes.length;
int argumentCount = args.length;
// Check if repackaging is needed:
// Check if repackaging is needed...
if (parameterCount != args.length ||
requiredParameterTypes[parameterCount - 1] !=
(args[argumentCount - 1] != null ? args[argumentCount - 1].getClass() : null)) {
@@ -421,10 +430,11 @@ public class ReflectionHelper {
/**
* An instance of ArgumentsMatchInfo describes what kind of match was achieved between two sets of arguments -
* the set that a method/constructor is expecting and the set that are being supplied at the point of invocation.
* If the kind indicates that conversion is required for some of the arguments then the arguments that require
* conversion are listed in the argsRequiringConversion array.
* An instance of ArgumentsMatchInfo describes what kind of match was achieved
* between two sets of arguments - the set that a method/constructor is expecting
* and the set that are being supplied at the point of invocation. If the kind
* indicates that conversion is required for some of the arguments then the arguments
* that require conversion are listed in the argsRequiringConversion array.
*/
public static class ArgumentsMatchInfo {

46
spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectiveMethodResolver.java
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2002-2014 the original author or authors.
* Copyright 2002-2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -66,13 +66,14 @@ public class ReflectiveMethodResolver implements MethodResolver {
}
/**
* This constructors allows the ReflectiveMethodResolver to be configured such that it will
* use a distance computation to check which is the better of two close matches (when there
* are multiple matches). Using the distance computation is intended to ensure matches
* are more closely representative of what a Java compiler would do when taking into
* account boxing/unboxing and whether the method candidates are declared to handle a
* supertype of the type (of the argument) being passed in.
* @param useDistance true if distance computation should be used when calculating matches
* This constructor allows the ReflectiveMethodResolver to be configured such that it
* will use a distance computation to check which is the better of two close matches
* (when there are multiple matches). Using the distance computation is intended to
* ensure matches are more closely representative of what a Java compiler would do
* when taking into account boxing/unboxing and whether the method candidates are
* declared to handle a supertype of the type (of the argument) being passed in.
* @param useDistance {@code true} if distance computation should be used when
* calculating matches; {@code false} otherwise
*/
public ReflectiveMethodResolver(boolean useDistance) {
this.useDistance = useDistance;
@@ -122,7 +123,19 @@ public class ReflectiveMethodResolver implements MethodResolver {
public int compare(Method m1, Method m2) {
int m1pl = m1.getParameterTypes().length;
int m2pl = m2.getParameterTypes().length;
return (new Integer(m1pl)).compareTo(m2pl);
// varargs methods go last
if (m1pl == m2pl) {
if (!m1.isVarArgs() && m2.isVarArgs()) {
return -1;
}
else if (m1.isVarArgs() && !m2.isVarArgs()) {
return 1;
}
else {
return 0;
}
}
return (m1pl < m2pl ? -1 : (m1pl > m2pl ? 1 : 0));
}
});
}
@@ -162,14 +175,17 @@ public class ReflectiveMethodResolver implements MethodResolver {
return new ReflectiveMethodExecutor(method, null);
}
else if (matchInfo.isCloseMatch()) {
if (!this.useDistance) {
closeMatch = method;
if (this.useDistance) {
int matchDistance = ReflectionHelper.getTypeDifferenceWeight(paramDescriptors, argumentTypes);
if (closeMatch == null || matchDistance < closeMatchDistance) {
// This is a better match...
closeMatch = method;
closeMatchDistance = matchDistance;
}
}
else {
int matchDistance = ReflectionHelper.getTypeDifferenceWeight(paramDescriptors, argumentTypes);
if (matchDistance < closeMatchDistance) {
// This is a better match...
closeMatchDistance = matchDistance;
// Take this as a close match if there isn't one already
if (closeMatch == null) {
closeMatch = method;
}
}

23
spring-expression/src/test/java/org/springframework/expression/spel/SpelReproTests.java
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2002-2014 the original author or authors.
* Copyright 2002-2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -1843,6 +1843,15 @@ public class SpelReproTests extends ExpressionTestCase {
assertEquals(NamedUser.class.getName(), expression.getValue(new NamedUser()));
}
@Test
public void SPR12803() throws Exception {
StandardEvaluationContext sec = new StandardEvaluationContext();
sec.setVariable("iterable", Collections.emptyList());
SpelExpressionParser parser = new SpelExpressionParser();
Expression expression = parser.parseExpression("T(org.springframework.expression.spel.SpelReproTests.GuavaLists).newArrayList(#iterable)");
assertTrue(expression.getValue(sec) instanceof ArrayList);
}
private static enum ABC { A, B, C }
@@ -1996,4 +2005,16 @@ public class SpelReproTests extends ExpressionTestCase {
}
}
public static class GuavaLists {
public static <T> List<T> newArrayList(Iterable<T> iterable) {
return new ArrayList<T>();
}
public static <T> List<T> newArrayList(Object... elements) {
throw new UnsupportedOperationException();
}
}
}