Package org.codehaus.groovy.runtime

Class ConversionHandler

java.lang.Object
org.codehaus.groovy.runtime.ConversionHandler
All Implemented Interfaces:
Serializable, InvocationHandler
Direct Known Subclasses:
ConvertedClosure, ConvertedMap
public abstract class ConversionHandler
extends Object
implements InvocationHandler, Serializable
This class is a general adapter to map a call to a Java interface to a given delegate.
See Also:
Serialized Form

  • Constructor Details

    • ConversionHandler

      public ConversionHandler​(Object delegate)
      Creates a ConversionHandler with an delegate.
      Parameters:
      delegate - the delegate
      Throws:
      IllegalArgumentException - if the given delegate is null

  • Method Details

    • getDelegate

      public Object getDelegate()
      Returns the delegate.
      Returns:
      the delegate

    • invoke

      public Object invoke​(Object proxy, Method method, Object[] args) throws Throwable
      This method is a default implementation for the invoke method given in InvocationHandler. Any call to a method with a declaring class that is not Object, excluding toString() and default methods is redirected to invokeCustom.

      Methods like equals and hashcode are called on the class itself instead of the delegate because they are considered fundamental methods that should not be overwritten. The toString() method gets special treatment as it is deemed to be a method that you might wish to override when called from Groovy. Interface default methods from Java 8 on the other hand are considered being default implementations you don't normally want to change. So they are called directly too

      In many scenarios, it is better to overwrite the invokeCustom method where the core Object related methods are filtered out.

      Specified by:
      invoke in interface InvocationHandler
      Parameters:
      proxy - the proxy
      method - the method
      args - the arguments
      Returns:
      the result of the invocation by method or delegate
      Throws:
      Throwable - if caused by the delegate or the method
      See Also:
      invokeCustom(Object, Method, Object[]), InvocationHandler.invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])

    • isDefaultMethod

      protected boolean isDefaultMethod​(Method method)

    • checkMethod

      protected boolean checkMethod​(Method method)

    • invokeCustom

      public abstract Object invokeCustom​(Object proxy, Method method, Object[] args) throws Throwable
      This method is called for all Methods not defined on Object. The delegate should be called here.
      Parameters:
      proxy - the proxy
      method - the method
      args - the arguments
      Returns:
      the result of the invocation of the delegate
      Throws:
      Throwable - any exception causes by the delegate
      See Also:
      invoke(Object, Method, Object[]), InvocationHandler.invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])

    • equals

      public boolean equals​(Object obj)
      Indicates whether some other object is "equal to" this one. The delegate is used if the class of the parameter and the current class are equal. In other cases the method will return false. The exact class is here used, if inheritance is needed, this method must be overwritten.
      Overrides:
      equals in class Object
      See Also:
      Object.equals(java.lang.Object)

    • hashCode

      public int hashCode()
      Returns a hash code value for the delegate.
      Overrides:
      hashCode in class Object
      See Also:
      Object.hashCode()

    • toString

      public String toString()
      Returns a String version of the delegate.
      Overrides:
      toString in class Object
      See Also:
      Object.toString()

    • isCoreObjectMethod

      public static boolean isCoreObjectMethod​(Method method)
      Checks whether a method is a core method from java.lang.Object. Such methods often receive special treatment because they are deemed fundamental enough to not be tampered with.
      Parameters:
      method - the method to check
      Returns:
      true if the method is deemed to be a core method