Package org.springframework.core

Class GenericTypeResolver

  • public abstract 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 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

      • resolveReturnTypeForGenericMethod

        @Deprecated
public static Class<?> resolveReturnTypeForGenericMethod​(Method method,
                                                         Object[] args,
                                                         ClassLoader classLoader)
        Deprecated.
        as of Spring Framework 4.3.8, superseded by ResolvableType usage
        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

        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

      • resolveReturnTypeArgument

        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

        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

        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 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