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

static class	ReflectionHelper.ArgsMatchKind
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.

Constructor Summary

ReflectionHelper()

Method Summary

(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 void	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 void	convertArguments(TypeConverter converter, java.lang.Object[] arguments, java.lang.Object methodOrCtor, int[] argumentsRequiringConversion, java.lang.Integer varargsPosition) 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.
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 array of types the method/constructor is expecting

suppliedArgTypes - the array of 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

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 array of types the method/constructor is expecting

suppliedArgTypes - the array of 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

convertArguments

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

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.

Parameters:

converter - the type converter to use for attempting conversions

arguments - the actual arguments that need conversion

methodOrCtor - the target Method or Constructor

argumentsRequiringConversion - details which of the input arguments need conversion

varargsPosition - the known position of the varargs argument, if any

Throws:

EvaluationException - if a problem occurs during conversion

convertAllArguments

public static void 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

Parameters:

converter - the converter to use for type conversions

arguments - the arguments to convert to the requested parameter types

method - the target Method

Throws:

SpelEvaluationException - if there is a problem with conversion

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 parameterTypes.

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