Module jdk.dynalink

Class BeansLinker

  • All Implemented Interfaces:
    GuardingDynamicLinker

    public class BeansLinker
    extends Object
    implements GuardingDynamicLinker
    A linker for ordinary Java objects. Normally used as the ultimate fallback linker by the DynamicLinkerFactory so it is given the chance to link calls to all objects that no other linker recognized. Specifically, this linker will:

    Overloaded method resolution is performed automatically for property setters, methods, and constructors. Additionally, manual overloaded method selection is supported by having a call site specify a name for a method that contains an explicit signature, e.g. StandardOperation.GET.withNamespace(METHOD).named("parseInt(String,int)") You can use non-qualified class names in such signatures regardless of those classes' packages, they will match any class with the same non-qualified name. You only have to use a fully qualified class name in case non-qualified class names would cause selection ambiguity (that is extremely rare). Overloaded resolution for constructors is not automatic as there is no logical place to attach that functionality to but if a language wishes to provide this functionality, it can use getConstructorMethod(Class, String) as a useful building block for it.

    Variable argument invocation is handled for both methods and constructors.

    Caller sensitive methods can be linked as long as they are otherwise public and link requests have call site descriptors carrying full-strength MethodHandles.Lookup objects and not weakened lookups or the public lookup.

    The behavior for handling missing members can be customized by passing a MissingMemberHandlerFactory to the constructor.

    The class also exposes various methods for discovery of available property and method names on classes and class instances, as well as access to per-class linkers using the getLinkerForClass(Class) method.

    • Constructor Detail

      • BeansLinker

        public BeansLinker()
        Creates a new beans linker. Equivalent to BeansLinker(MissingMemberHandlerFactory) with null passed as the missing member handler factory, resulting in the default behavior for linking and evaluating missing members.
      • BeansLinker

        public BeansLinker​(MissingMemberHandlerFactory missingMemberHandlerFactory)
        Creates a new beans linker with the specified factory for creating missing member handlers. The passed factory can be null if the default behavior is adequate. See MissingMemberHandlerFactory for details.
        Parameters:
        missingMemberHandlerFactory - a factory for creating handlers for operations on missing members.
    • Method Detail

      • getLinkerForClass

        public TypeBasedGuardingDynamicLinker getLinkerForClass​(Class<?> clazz)
        Returns a bean linker for a particular single class. Useful when you need to override or extend the behavior of linking for some classes in your language runtime's linker, but still want to delegate to the default behavior in some cases.
        Parameters:
        clazz - the class
        Returns:
        a bean linker for that class
      • isDynamicMethod

        public static boolean isDynamicMethod​(Object obj)
        Returns true if the object is a Java dynamic method (e.g., one obtained through a GET:METHOD operation on a Java object or StaticClass or through getConstructorMethod(Class, String).
        Parameters:
        obj - the object we want to test for being a Java dynamic method.
        Returns:
        true if it is a dynamic method, false otherwise.
      • isDynamicConstructor

        public static boolean isDynamicConstructor​(Object obj)
        Returns true if the object is a Java constructor (obtained through getConstructorMethod(Class, String)}.
        Parameters:
        obj - the object we want to test for being a Java constructor.
        Returns:
        true if it is a constructor, false otherwise.
      • getConstructorMethod

        public static Object getConstructorMethod​(Class<?> clazz,
                                                  String signature)
        Return the dynamic method of constructor of the given class and the given signature. This method is useful for exposing a functionality for selecting an overloaded constructor based on an explicit signature, as this functionality is not otherwise exposed by Dynalink as StaticClass objects act as overloaded constructors without explicit signature selection. Example usage would be: getConstructorMethod(java.awt.Color.class, "int, int, int").
        Parameters:
        clazz - the class
        signature - full signature of the constructor. Note how you can use names of primitive types, array names with normal Java notation (e.g. "int[]"), and normally you can even use unqualified class names (e.g. "String, List" instead of "java.lang.String, java.util.List" as long as they don't cause ambiguity in the specific parameter position.
        Returns:
        dynamic method for the constructor or null if no constructor with the specified signature exists.
      • getReadableInstancePropertyNames

        public static Set<String> getReadableInstancePropertyNames​(Class<?> clazz)
        Returns a set of names of all readable instance properties of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all readable instance properties of a class.
      • getWritableInstancePropertyNames

        public static Set<String> getWritableInstancePropertyNames​(Class<?> clazz)
        Returns a set of names of all writable instance properties of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all writable instance properties of a class.
      • getInstanceMethodNames

        public static Set<String> getInstanceMethodNames​(Class<?> clazz)
        Returns a set of names of all instance methods of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all instance methods of a class.
      • getReadableStaticPropertyNames

        public static Set<String> getReadableStaticPropertyNames​(Class<?> clazz)
        Returns a set of names of all readable static properties of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all readable static properties of a class.
      • getWritableStaticPropertyNames

        public static Set<String> getWritableStaticPropertyNames​(Class<?> clazz)
        Returns a set of names of all writable static properties of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all writable static properties of a class.
      • getStaticMethodNames

        public static Set<String> getStaticMethodNames​(Class<?> clazz)
        Returns a set of names of all static methods of a class.
        Parameters:
        clazz - the class
        Returns:
        a set of names of all static methods of a class.