org.springframework.core

Class GenericTypeResolver

java.lang.Object

org.springframework.core.GenericTypeResolver

public abstract class GenericTypeResolver
extends java.lang.Object

Helper class for resolving generic types against type variables.

Mainly intended for usage within the framework, resolving method parameter types even when they are declared generically.

Since:

2.5.2

Author:

Juergen Hoeller, Rob Harrop, Sam Brannen, Phillip Webb

See Also:

GenericCollectionTypeResolver

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	GenericTypeResolver.TypeVariableMapVariableResolver

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type>>	typeVariableCache Cache from Class to TypeVariable Map

Constructor Summary

Constructors

Constructor and Description
GenericTypeResolver()

Method Summary

Modifier and Type	Method and Description
private static void	buildTypeVariableMap(ResolvableType type, java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type> typeVariableMap)
private static java.lang.Class<?>	getSingleGeneric(ResolvableType resolvableType)
static java.lang.reflect.Type	getTargetType(MethodParameter methodParameter) Deprecated. as of Spring 4.0, use MethodParameter.getGenericParameterType()
static java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type>	getTypeVariableMap(java.lang.Class<?> clazz) Deprecated. as of Spring 4.0 in favor of ResolvableType
static java.lang.Class<?>	resolveParameterType(MethodParameter methodParameter, java.lang.Class<?> implementationClass) Determine the target type for the given generic parameter type.
static java.lang.Class<?>	resolveReturnType(java.lang.reflect.Method method, java.lang.Class<?> clazz) Determine the target type for the generic return type of the given method, where formal type variables are declared on the given class.
static java.lang.Class<?>	resolveReturnTypeArgument(java.lang.reflect.Method method, java.lang.Class<?> genericIfc) Resolve the single type argument of the given generic interface against the given target method which is assumed to return the given interface or an implementation of it.
static java.lang.Class<?>	resolveReturnTypeForGenericMethod(java.lang.reflect.Method method, java.lang.Object[] args, java.lang.ClassLoader classLoader) Determine the target type for the generic return type of the given generic method, where formal type variables are declared on the given method itself.
static java.lang.Class<?>	resolveType(java.lang.reflect.Type genericType, java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type> map) Deprecated. as of Spring 4.0 in favor of ResolvableType
static java.lang.Class<?>	resolveTypeArgument(java.lang.Class<?> clazz, java.lang.Class<?> genericIfc) Resolve the single type argument of the given generic interface against the given target class which is assumed to implement the generic interface and possibly declare a concrete type for its type variable.
static java.lang.Class<?>[]	resolveTypeArguments(java.lang.Class<?> clazz, java.lang.Class<?> genericIfc) Resolve the type arguments of the given generic interface against the given target class which is assumed to implement the generic interface and possibly declare concrete types for its type variables.

Methods inherited from class java.lang.Object

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

Field Detail

typeVariableCache

private static final java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type>> typeVariableCache

Cache from Class to TypeVariable Map

Constructor Detail

GenericTypeResolver

public GenericTypeResolver()

Method Detail

getTargetType

@Deprecated
public static java.lang.reflect.Type getTargetType(MethodParameter methodParameter)

Deprecated. as of Spring 4.0, use MethodParameter.getGenericParameterType()

Determine the target type for the given parameter specification.

Parameters:

methodParameter - the method parameter specification

Returns:

the corresponding generic parameter type

resolveParameterType

public static java.lang.Class<?> resolveParameterType(MethodParameter methodParameter,
                                                      java.lang.Class<?> implementationClass)

Determine the target type for the given generic parameter type.

Parameters:

methodParameter - the method parameter specification

implementationClass - the class to resolve type variables against

Returns:

the corresponding generic parameter or return type

resolveReturnType

public static java.lang.Class<?> resolveReturnType(java.lang.reflect.Method method,
                                                   java.lang.Class<?> clazz)

Determine the target type for the generic return type of the given method, where formal type variables are declared on the given class.

Parameters:

method - the method to introspect

clazz - the class to resolve type variables against

Returns:

the corresponding generic parameter or return type

See Also:

resolveReturnTypeForGenericMethod(java.lang.reflect.Method, java.lang.Object[], java.lang.ClassLoader)

resolveReturnTypeForGenericMethod

public static java.lang.Class<?> resolveReturnTypeForGenericMethod(java.lang.reflect.Method method,
                                                                   java.lang.Object[] args,
                                                                   java.lang.ClassLoader classLoader)

Determine the target type for the generic return type of the given generic method, where formal type variables are declared on the given method itself.

For example, given a factory method with the following signature, if resolveReturnTypeForGenericMethod() is invoked with the reflected method for creatProxy() and an Object[] array containing MyService.class, resolveReturnTypeForGenericMethod() will infer that the target return type is MyService.

public static <T> T createProxy(Class<T> clazz)

Possible Return Values

• the target return type, if it can be inferred
• the standard return type, if the given method does not declare any formal type variables
• the standard return type, if the target return type cannot be inferred (e.g., due to type erasure)
• null, if the length of the given arguments array is shorter than the length of the formal argument list for the given method

Parameters:

method - the method to introspect, never null

args - the arguments that will be supplied to the method when it is invoked (never null)

classLoader - the ClassLoader to resolve class names against, if necessary (may be null)

Returns:

the resolved target return type, the standard return type, or null

Since:

3.2.5

See Also:

resolveReturnType(java.lang.reflect.Method, java.lang.Class<?>)

resolveReturnTypeArgument

public static java.lang.Class<?> resolveReturnTypeArgument(java.lang.reflect.Method method,
                                                           java.lang.Class<?> genericIfc)

Resolve the single type argument of the given generic interface against the given target method which is assumed to return the given interface or an implementation of it.

Parameters:

method - the target method to check the return type of

genericIfc - the generic interface or superclass to resolve the type argument from

Returns:

the resolved parameter type of the method return type, or null if not resolvable or if the single argument is of type WildcardType.

resolveTypeArgument

public static java.lang.Class<?> resolveTypeArgument(java.lang.Class<?> clazz,
                                                     java.lang.Class<?> genericIfc)

Resolve the single type argument of the given generic interface against the given target class which is assumed to implement the generic interface and possibly declare a concrete type for its type variable.

Parameters:

clazz - the target class to check against

genericIfc - the generic interface or superclass to resolve the type argument from

Returns:

the resolved type of the argument, or null if not resolvable

getSingleGeneric

private static java.lang.Class<?> getSingleGeneric(ResolvableType resolvableType)

resolveTypeArguments

public static java.lang.Class<?>[] resolveTypeArguments(java.lang.Class<?> clazz,
                                                        java.lang.Class<?> genericIfc)

Resolve the type arguments of the given generic interface against the given target class which is assumed to implement the generic interface and possibly declare concrete types for its type variables.

Parameters:

clazz - the target class to check against

genericIfc - the generic interface or superclass to resolve the type argument from

Returns:

the resolved type of each argument, with the array size matching the number of actual type arguments, or null if not resolvable

resolveType

@Deprecated
public static java.lang.Class<?> resolveType(java.lang.reflect.Type genericType,
                                                         java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type> map)

Deprecated. as of Spring 4.0 in favor of ResolvableType

Resolve the specified generic type against the given TypeVariable map.

Parameters:

genericType - the generic type to resolve

map - the TypeVariable Map to resolved against

Returns:

the type if it resolves to a Class, or Object.class otherwise

getTypeVariableMap

@Deprecated
public static java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type> getTypeVariableMap(java.lang.Class<?> clazz)

Deprecated. as of Spring 4.0 in favor of ResolvableType

Build a mapping of TypeVariable names to concrete classes for the specified Class. Searches all super types, enclosing types and interfaces.

buildTypeVariableMap

private static void buildTypeVariableMap(ResolvableType type,
                                         java.util.Map<java.lang.reflect.TypeVariable,java.lang.reflect.Type> typeVariableMap)