org.springframework.core

Class GenericTypeResolver

java.lang.Object

org.springframework.core.GenericTypeResolver

public final class GenericTypeResolver
extends 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

Method Summary

Modifier and Type	Method and Description
static Map<TypeVariable,Type>	getTypeVariableMap(Class<?> clazz) Build a mapping of TypeVariable names to concrete classes for the specified Class.
static Class<?>	resolveParameterType(MethodParameter methodParameter, Class<?> implementationClass) Determine the target type for the given generic parameter type.
static Class<?>	resolveReturnType(Method method, 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 Class<?>	resolveReturnTypeArgument(Method method, 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 Type	resolveType(Type genericType, Class<?> contextClass) Resolve the given generic type against the given context class, substituting type variables as far as possible.
static Class<?>	resolveType(Type genericType, Map<TypeVariable,Type> map) Resolve the specified generic type against the given TypeVariable map.
static Class<?>	resolveTypeArgument(Class<?> clazz, 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 Class<?>[]	resolveTypeArguments(Class<?> clazz, 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

Method Detail

resolveParameterType

public static Class<?> resolveParameterType(MethodParameter methodParameter,
                                            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 Class<?> resolveReturnType(Method method,
                                         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

resolveReturnTypeArgument

@Nullable
public static Class<?> resolveReturnTypeArgument(Method method,
                                                           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

@Nullable
public static Class<?> resolveTypeArgument(Class<?> clazz,
                                                     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

resolveTypeArguments

@Nullable
public static Class<?>[] resolveTypeArguments(Class<?> clazz,
                                                        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

public static Type resolveType(Type genericType,
                               @Nullable
                               Class<?> contextClass)

Resolve the given generic type against the given context class, substituting type variables as far as possible.

Parameters:

genericType - the (potentially) generic type

contextClass - a context class for the target type, for example a class in which the target type appears in a method signature (can be null)

Returns:

the resolved type (possibly the given generic type as-is)

Since:

5.0

resolveType

public static Class<?> resolveType(Type genericType,
                                   Map<TypeVariable,Type> map)

Resolve the specified generic type against the given TypeVariable map.

Used by Spring Data.

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

public static Map<TypeVariable,Type> getTypeVariableMap(Class<?> clazz)

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

See Also:

resolveType(Type, Map)