org.restlet.routing

Class Filter

java.lang.Object

org.restlet.Restlet

org.restlet.routing.Filter

All Implemented Interfaces:

Uniform

Direct Known Subclasses:

Authenticator, Authorizer, Decoder, Encoder, Extractor, LogFilter, RangeFilter, Route, StatusFilter, TemplateDispatcher, TunnelFilter, Validator

public abstract class Filter
extends Restlet

Restlet filtering calls before passing them to an attached Restlet. The purpose is to do some pre-processing or post-processing on the calls going through it before or after they are actually handled by an attached Restlet. Also note that you can attach and detach targets while handling incoming calls as the filter is ensured to be thread-safe.

Concurrency note: instances of this class or its subclasses can be invoked by several threads at the same time and therefore must be thread-safe. You should be especially careful when storing state in member variables.

Author:

Jerome Louvel

Field Summary

Fields

Modifier and Type	Field and Description
static int	CONTINUE Indicates that the request processing should continue normally.
static int	SKIP Indicates that after the beforeHandle(Request, Response) method, the request processing should skip the doHandle(Request, Response) method to continue with the afterHandle(Request, Response) method.
static int	STOP Indicates that the request processing should stop and return the current response from the filter.

Constructor Summary

Constructors

Constructor and Description
Filter() Constructor.
Filter(Context context) Constructor.
Filter(Context context, Restlet next) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	afterHandle(Request request, Response response) Allows filtering after processing by the next Restlet.
protected int	beforeHandle(Request request, Response response) Allows filtering before processing by the next Restlet.
protected int	doHandle(Request request, Response response) Handles the call by distributing it to the next Restlet.
Restlet	getNext() Returns the next Restlet.
void	handle(Request request, Response response) Handles a call by first invoking the beforeHandle() method for pre-filtering, then distributing the call to the next Restlet via the doHandle() method.
boolean	hasNext() Indicates if there is a next Restlet.
void	setNext(Class<? extends ServerResource> targetClass) Sets the next Restlet as a Finder for a given ServerResource class.
void	setNext(Restlet next) Sets the next Restlet.
void	start() Starts the filter and the next Restlet if attached.
void	stop() Stops the filter and the next Restlet if attached.

Methods inherited from class org.restlet.Restlet

createFinder, finalize, getApplication, getAuthor, getContext, getDescription, getFinderClass, getLogger, getName, getOwner, handle, handle, handle, isStarted, isStopped, setAuthor, setContext, setDescription, setFinderClass, setName, setOwner

Methods inherited from class java.lang.Object

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

Field Detail

CONTINUE

public static final int CONTINUE

Indicates that the request processing should continue normally. If returned from the beforeHandle(Request, Response) method, the filter then invokes the doHandle(Request, Response) method. If returned from the doHandle(Request, Response) method, the filter then invokes the afterHandle(Request, Response) method.

See Also:

Constant Field Values

SKIP

public static final int SKIP

Indicates that after the beforeHandle(Request, Response) method, the request processing should skip the doHandle(Request, Response) method to continue with the afterHandle(Request, Response) method.

See Also:

Constant Field Values

STOP

public static final int STOP

Indicates that the request processing should stop and return the current response from the filter.

See Also:

Constant Field Values

Constructor Detail

Filter

public Filter()

Constructor.

Filter

public Filter(Context context)

Constructor.

Parameters:

context - The context.

Filter

public Filter(Context context,
      Restlet next)

Constructor.

Parameters:

context - The context.

next - The next Restlet.

Method Detail

afterHandle

protected void afterHandle(Request request,
               Response response)

Allows filtering after processing by the next Restlet. Does nothing by default.

Parameters:

request - The request to handle.

response - The response to update.

beforeHandle

protected int beforeHandle(Request request,
               Response response)

Allows filtering before processing by the next Restlet. Returns CONTINUE by default.

Parameters:

request - The request to handle.

response - The response to update.

Returns:

The continuation status. Either CONTINUE or SKIP or STOP.

doHandle

protected int doHandle(Request request,
           Response response)

Handles the call by distributing it to the next Restlet. If no Restlet is attached, then a Status.SERVER_ERROR_INTERNAL status is returned. Returns CONTINUE by default.

Parameters:

request - The request to handle.

response - The response to update.

Returns:

The continuation status. Either CONTINUE or STOP.

getNext

public Restlet getNext()

Returns the next Restlet.

Returns:

The next Restlet or null.

handle

public final void handle(Request request,
          Response response)

Handles a call by first invoking the beforeHandle() method for pre-filtering, then distributing the call to the next Restlet via the doHandle() method. When the handling is completed, it finally invokes the afterHandle() method for post-filtering.

Specified by:

handle in interface Uniform

Overrides:

handle in class Restlet

Parameters:

request - The request to handle.

response - The response to update.

hasNext

public boolean hasNext()

Indicates if there is a next Restlet.

Returns:

True if there is a next Restlet.

setNext

public void setNext(Class<? extends ServerResource> targetClass)

Sets the next Restlet as a Finder for a given ServerResource class. When the call is delegated to the Finder instance, a new instance of the resource class will be created and will actually handle the request.

Parameters:

targetClass - The target resource class to attach.

setNext

public void setNext(Restlet next)

Sets the next Restlet. In addition, this method will set the context of the next Restlet if it is null by passing a reference to its own context.

Parameters:

next - The next Restlet.

start

public void start()
           throws Exception

Starts the filter and the next Restlet if attached.

Overrides:

start in class Restlet

Throws:

Exception

stop

public void stop()
          throws Exception

Stops the filter and the next Restlet if attached.

Overrides:

stop in class Restlet

Throws:

Exception