org.springframework.expression.spel.support

Class ReflectionHelper

java.lang.Object

org.springframework.expression.spel.support.ReflectionHelper

public class ReflectionHelper
extends java.lang.Object

Utility methods used by the reflection resolver code to discover the appropriate methods/constructors and fields that should be used in expressions.

Since:

3.0

Author:

Andy Clement, Juergen Hoeller

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	ReflectionHelper.ArgumentsMatchInfo 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.
(package private) static class	ReflectionHelper.ArgumentsMatchKind

Constructor Summary

Constructors

Constructor and Description
ReflectionHelper()

Method Summary

Modifier and Type	Method and Description
(package private) static ReflectionHelper.ArgumentsMatchInfo	compareArguments(java.util.List<TypeDescriptor> expectedArgTypes, java.util.List<TypeDescriptor> suppliedArgTypes, TypeConverter typeConverter) Compare argument arrays and return information about whether they match.
(package private) static ReflectionHelper.ArgumentsMatchInfo	compareArgumentsVarargs(java.util.List<TypeDescriptor> expectedArgTypes, java.util.List<TypeDescriptor> suppliedArgTypes, TypeConverter typeConverter) Compare argument arrays and return information about whether they match.
static boolean	convertAllArguments(TypeConverter converter, java.lang.Object[] arguments, java.lang.reflect.Method method) Convert a supplied set of arguments into the requested types.
(package private) static boolean	convertArguments(TypeConverter converter, java.lang.Object[] arguments, java.lang.Object methodOrCtor, java.lang.Integer varargsPosition) Takes an input set of argument values and converts them to the types specified as the required parameter types.
static int	getTypeDifferenceWeight(java.util.List<TypeDescriptor> paramTypes, java.util.List<TypeDescriptor> argTypes) Based on MethodInvoker.getTypeDifferenceWeight(Class[], Object[]) but operates on TypeDescriptors.
private static boolean	isFirstEntryInArray(java.lang.Object value, java.lang.Object possibleArray) Check if the supplied value is the first entry in the array represented by the possibleArray value.
static java.lang.Object[]	setupArgumentsForVarargsInvocation(java.lang.Class<?>[] requiredParameterTypes, java.lang.Object... args) Package up the arguments so that they correctly match what is expected in parameterTypes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReflectionHelper

public ReflectionHelper()

Method Detail

compareArguments

static ReflectionHelper.ArgumentsMatchInfo compareArguments(java.util.List<TypeDescriptor> expectedArgTypes,
                                                            java.util.List<TypeDescriptor> suppliedArgTypes,
                                                            TypeConverter typeConverter)

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.

Parameters:

expectedArgTypes - the types the method/constructor is expecting

suppliedArgTypes - the types that are being supplied at the point of invocation

typeConverter - a registered type converter

Returns:

a MatchInfo object indicating what kind of match it was, or null if it was not a match

getTypeDifferenceWeight

public static int getTypeDifferenceWeight(java.util.List<TypeDescriptor> paramTypes,
                                          java.util.List<TypeDescriptor> argTypes)

Based on MethodInvoker.getTypeDifferenceWeight(Class[], Object[]) but operates on TypeDescriptors.

compareArgumentsVarargs

static ReflectionHelper.ArgumentsMatchInfo compareArgumentsVarargs(java.util.List<TypeDescriptor> expectedArgTypes,
                                                                   java.util.List<TypeDescriptor> suppliedArgTypes,
                                                                   TypeConverter typeConverter)

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.

Parameters:

expectedArgTypes - the types the method/constructor is expecting

suppliedArgTypes - the types that are being supplied at the point of invocation

typeConverter - a registered type converter

Returns:

a MatchInfo object indicating what kind of match it was, or null if it was not a match

convertAllArguments

public static boolean convertAllArguments(TypeConverter converter,
                                          java.lang.Object[] arguments,
                                          java.lang.reflect.Method method)
                                   throws SpelEvaluationException

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 - a subsequent call to setupArgumentsForVarargsInvocation handles that.

Parameters:

converter - the converter to use for type conversions

arguments - the arguments to convert to the requested parameter types

method - the target Method

Returns:

true if some kind of conversion occurred on the argument

Throws:

SpelEvaluationException - if there is a problem with conversion

convertArguments

static boolean convertArguments(TypeConverter converter,
                                java.lang.Object[] arguments,
                                java.lang.Object methodOrCtor,
                                java.lang.Integer varargsPosition)
                         throws EvaluationException

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.

Parameters:

converter - the type converter to use for attempting conversions

arguments - the actual arguments that need conversion

methodOrCtor - the target Method or Constructor

varargsPosition - the known position of the varargs argument, if any (null if not varargs)

Returns:

true if some kind of conversion occurred on an argument

Throws:

EvaluationException - if a problem occurs during conversion

isFirstEntryInArray

private static boolean isFirstEntryInArray(java.lang.Object value,
                                           java.lang.Object possibleArray)

Check if the supplied value is the first entry in the array represented by the possibleArray value.

Parameters:

value - the value to check for in the array

possibleArray - an array object that may have the supplied value as the first element

Returns:

true if the supplied value is the first entry in the array

setupArgumentsForVarargsInvocation

public static java.lang.Object[] setupArgumentsForVarargsInvocation(java.lang.Class<?>[] requiredParameterTypes,
                                                                    java.lang.Object... args)

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 types.

Parameters:

requiredParameterTypes - the types of the parameters for the invocation

args - the arguments to be setup ready for the invocation

Returns:

a repackaged array of arguments where any varargs setup has been done