org.geotools.util.decorate

Interface Wrapper

All Superinterfaces:

Wrapper

public interface Wrapper
extends Wrapper

Interface for classes which provide the ability to retrieve the delegate instance when the instance in question is in fact a proxy/decorator class.

Developers may wish to gain access to the resources that are wrapped (the delegates) as proxy class instances representing the the actual resources.

This interface extends JDK Wrapper class, overriding the thrown exception with a more meaningful named one.

Method Summary

Modifier and Type	Method and Description
boolean	isWrapperFor(Class<?> iface) Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does.
<T> T	unwrap(Class<T> iface) Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.

Method Detail

isWrapperFor

boolean isWrapperFor(Class<?> iface)

Returns true if this either implements the interface argument or is directly or indirectly a wrapper for an object that does. Returns false otherwise. If this implements the interface then return true, else if this is a wrapper then return the result of recursively calling isWrapperFor on the wrapped object. If this does not implement the interface and is not a wrapper, return false. This method should be implemented as a low-cost operation compared to unwrap so that callers can use this method to avoid expensive unwrap calls that may fail. If this method returns true then calling unwrap with the same argument should succeed.

Specified by:

isWrapperFor in interface Wrapper

Parameters:

iface - a Class defining an interface.

Returns:

true if this implements the interface or directly or indirectly wraps an object that does.

unwrap

<T> T unwrap(Class<T> iface)
      throws IllegalArgumentException

Returns an object that implements the given interface to allow access to non-standard methods, or standard methods not exposed by the proxy.

If the receiver implements the interface then the result is the receiver or a proxy for the receiver. If the receiver is a wrapper and the wrapped object implements the interface then the result is the wrapped object or a proxy for the wrapped object. Otherwise return the the result of calling unwrap recursively on the wrapped object or a proxy for that result. If the receiver is not a wrapper and does not implement the interface, then an IllegalArgumentException is thrown.

Specified by:

unwrap in interface Wrapper

Parameters:

iface - A Class defining an interface that the result must implement.

Returns:

an object that implements the interface. May be a proxy for the actual implementing object.

Throws:

IllegalArgumentException - If no object found that implements the interface