org.astrogrid.samp.xmlrpc

Class ActorHandler

java.lang.Object

org.astrogrid.samp.xmlrpc.ActorHandler

All Implemented Interfaces:

SampXmlRpcHandler

Direct Known Subclasses:

WebHubXmlRpcHandler

public abstract class ActorHandler
extends Object
implements SampXmlRpcHandler

Utility class to facilitate constructing a SampXmlRpcHandler which handles particular named methods. You supply at construction time an interface which defines the methods to be handled and an object which implements that interface. This object then uses reflection to invoke the correct methods on the implementation object as they are required from incoming XML-RPC execute requests. This insulates the implementation object from having to worry about any XML-RPC specifics.

Since:

15 Jul 2008

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
ActorHandler(String prefix, Class actorType, Object actor) Constructor.

Method Summary

Modifier and Type	Method and Description
boolean	canHandleCall(String fqName) Returns true if this handler should be able to process given XML-RPC method.
Object	getActor() Returns the implementation object for this handler.
Object	handleCall(String fqName, List params, Object reqInfo) Processes an XML-RPC call.
protected abstract Object	invokeMethod(Method method, Object obj, Object[] args) Invokes a method reflectively on an object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ActorHandler

public ActorHandler(String prefix,
                    Class actorType,
                    Object actor)

Constructor.

Parameters:

prefix - string prepended to every method name in the actorType interface to form the XML-RPC methodName element

actorType - interface defining the XML-RPC methods

actor - object implementing actorType

Method Detail

canHandleCall

public boolean canHandleCall(String fqName)

Description copied from interface: SampXmlRpcHandler

Returns true if this handler should be able to process given XML-RPC method.

Specified by:

canHandleCall in interface SampXmlRpcHandler

Parameters:

fqName - method name

handleCall

public Object handleCall(String fqName,
                         List params,
                         Object reqInfo)
                  throws Exception

Description copied from interface: SampXmlRpcHandler

Processes an XML-RPC call. This method should only be called if canHandleCall(method) returns true. The params list and the return value must be SAMP-compatible, that is only Strings, Lists and String-keyed Maps are allowed in the data structures. The reqInfo parameter may be used to provide additional information about the XML-RPC request, for instance the originating host; this is implementation specific, and may be null.

Specified by:

handleCall in interface SampXmlRpcHandler

Parameters:

fqName - XML-RPC method name

params - XML-RPC parameter list (SAMP-compatible)

reqInfo - optional additional request information; may be null

Returns:

return value (SAMP-compatible)

Throws:

Exception

getActor

public Object getActor()

Returns the implementation object for this handler.

Returns:

implementation object

invokeMethod

protected abstract Object invokeMethod(Method method,
                                       Object obj,
                                       Object[] args)
                                throws IllegalAccessException,
                                       InvocationTargetException

Invokes a method reflectively on an object. This method should be implemented in the obvious way, that is return method.invoke(obj,params).

If the implementation is effectively prescribed, why is this abstract method here? It's tricky. The reason is so that reflective method invocation from this class is done by code within the actor implementation class itself rather than by code in the superclass, ActorHandler. That in turn means that the actorType class specified in the constructor does not need to be visible from ActorHandler's package, only from the package where the implementation class lives.

Parameters:

method - method to invoke

obj - object to invoke the method on

args - arguments for the method call

Throws:

IllegalAccessException

InvocationTargetException

See Also:

Method.invoke(java.lang.Object, java.lang.Object...)