Class MethodInvoker

  • public class MethodInvoker
    extends Object
    Helper class that allows for specifying a method to invoke in a declarative fashion, be it static or non-static.

    Usage: Specify "targetClass"/"targetMethod" or "targetObject"/"targetMethod", optionally specify arguments, prepare the invoker. Afterwards, you may invoke the method any number of times, obtaining the invocation result.

    Colin Sampaleanu, Juergen Hoeller
    See Also:
    prepare(), invoke()
    • Constructor Detail

      • MethodInvoker

        public MethodInvoker()
    • Method Detail

      • getTargetClass

        public Class<?> getTargetClass()
        Return the target class on which to call the target method.
      • getTargetObject

        public Object getTargetObject()
        Return the target object on which to call the target method.
      • getTargetMethod

        public String getTargetMethod()
        Return the name of the method to be invoked.
      • setArguments

        public void setArguments(Object[] arguments)
        Set arguments for the method invocation. If this property is not set, or the Object array is of length 0, a method with no arguments is assumed.
      • getArguments

        public Object[] getArguments()
        Return the arguments for the method invocation.
      • resolveClassName

        protected Class<?> resolveClassName(String className)
                                     throws ClassNotFoundException
        Resolve the given class name into a Class.

        The default implementations uses ClassUtils.forName, using the thread context class loader.

        className - the class name to resolve
        the resolved Class
        ClassNotFoundException - if the class name was invalid
      • getPreparedMethod

        public Method getPreparedMethod()
                                 throws IllegalStateException
        Return the prepared Method object that will be invoked.

        Can for example be used to determine the return type.

        the prepared Method object (never null)
        IllegalStateException - if the invoker hasn't been prepared yet
        See Also:
        prepare(), invoke()
      • isPrepared

        public boolean isPrepared()
        Return whether this invoker has been prepared already, i.e. whether it allows access to getPreparedMethod() already.
      • getTypeDifferenceWeight

        public static int getTypeDifferenceWeight(Class<?>[] paramTypes,
                                  Object[] args)
        Algorithm that judges the match between the declared parameter types of a candidate method and a specific list of arguments that this method is supposed to be invoked with.

        Determines a weight that represents the class hierarchy difference between types and arguments. A direct match, i.e. type Integer -> arg of class Integer, does not increase the result - all direct matches means weight 0. A match between type Object and arg of class Integer would increase the weight by 2, due to the superclass 2 steps up in the hierarchy (i.e. Object) being the last one that still matches the required type Object. Type Number and class Integer would increase the weight by 1 accordingly, due to the superclass 1 step up the hierarchy (i.e. Number) still matching the required type Number. Therefore, with an arg of type Integer, a constructor (Integer) would be preferred to a constructor (Number) which would in turn be preferred to a constructor (Object). All argument weights get accumulated.

        Note: This is the algorithm used by MethodInvoker itself and also the algorithm used for constructor and factory method selection in Spring's bean container (in case of lenient constructor resolution which is the default for regular bean definitions).

        paramTypes - the parameter types to match
        args - the arguments to match
        the accumulated weight for all arguments