org.codehaus.groovy.runtime

Class ConversionHandler

java.lang.Object

org.codehaus.groovy.runtime.ConversionHandler

All Implemented Interfaces:

java.io.Serializable, java.lang.reflect.InvocationHandler

Direct Known Subclasses:

ConvertedClosure, ConvertedMap

public abstract class ConversionHandler
extends java.lang.Object
implements java.lang.reflect.InvocationHandler, java.io.Serializable

This class is a general adapter to map a call to a Java interface to a given delegate.

Author:

Ben Yu, Jochen Theodorou

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ConversionHandler(java.lang.Object delegate) Creates a ConversionHandler with an delegate.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkMethod(java.lang.reflect.Method method)
boolean	equals(java.lang.Object obj) Indicates whether some other object is "equal to" this one.
java.lang.Object	getDelegate() Returns the delegate.
int	hashCode() Returns a hash code value for the delegate.
java.lang.Object	invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) This method is a default implementation for the invoke method given in InvocationHandler.
abstract java.lang.Object	invokeCustom(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) This method is called for all Methods not defined on Object.
static boolean	isCoreObjectMethod(java.lang.reflect.Method method) Checks whether a method is a core method from java.lang.Object.
protected boolean	isDefaultMethod(java.lang.reflect.Method method)
java.lang.String	toString() Returns a String version of the delegate.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ConversionHandler

public ConversionHandler(java.lang.Object delegate)

Creates a ConversionHandler with an delegate.

Parameters:

delegate - the delegate

Throws:

java.lang.IllegalArgumentException - if the given delegate is null

Method Detail

getDelegate

public java.lang.Object getDelegate()

Returns the delegate.

Returns:

the delegate

invoke

public java.lang.Object invoke(java.lang.Object proxy,
                               java.lang.reflect.Method method,
                               java.lang.Object[] args)
                        throws java.lang.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 java.lang.reflect.InvocationHandler

Parameters:

proxy - the proxy

method - the method

args - the arguments

Returns:

the result of the invocation by method or delegate

Throws:

java.lang.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(java.lang.reflect.Method method)

checkMethod

protected boolean checkMethod(java.lang.reflect.Method method)

invokeCustom

public abstract java.lang.Object invokeCustom(java.lang.Object proxy,
                                              java.lang.reflect.Method method,
                                              java.lang.Object[] args)
                                       throws java.lang.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:

java.lang.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(java.lang.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 java.lang.Object

See Also:

Object.equals(java.lang.Object)

hashCode

public int hashCode()

Returns a hash code value for the delegate.

Overrides:

hashCode in class java.lang.Object

See Also:

Object.hashCode()

toString

public java.lang.String toString()

Returns a String version of the delegate.

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()

isCoreObjectMethod

public static boolean isCoreObjectMethod(java.lang.reflect.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