Class DeferredHandler

  extended by sunlabs.brazil.handler.DeferredHandler (view source)
All Implemented Interfaces:

public class DeferredHandler
extends Object
implements Handler

Wrap another handler, deferring its initialization until request time. This allows handlers to be configured, but not initialized until a first use is attempted.

Normally, when a handler's class is first resolved, if any of the dependent classes are not available, an error will occur, terminating the server. Using this handler, other handlers can be conditionally configured based on the availability of other specified classes at run time.

NOTE: This functionallity should be integrated into the ChainHandler, eliminating the need for this one.

Request Properties

The token representing the handler to conditionally configure. This is used as the handler's prefix
The names of classes required to be resolvable before configuring the handler
The name of the handler class.

Constructor Summary
Method Summary
 boolean init(Server server, String prefix)
          Remember the server for deferred initialization.
 boolean respond(Request request)
          Dispatch to the handler, installing it if needed
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


public DeferredHandler()
Method Detail


public boolean init(Server server,
                    String prefix)
Remember the server for deferred initialization.

Specified by:
init in interface Handler
server - The HTTP server that created this Handler. Typical Handlers will use Server.props to obtain run-time configuration information.
prefix - The handlers name. The string this Handler may prepend to all of the keys that it uses to extract configuration information from Server.props. This is set (by the Server and ChainHandler) to help avoid configuration parameter namespace collisions.
true if this Handler initialized successfully, false otherwise. If false is returned, this Handler should not be used.


public boolean respond(Request request)
                throws IOException
Dispatch to the handler, installing it if needed

Specified by:
respond in interface Handler
request - The Request object that represents the HTTP request.
true if the request was handled. A request was handled if a response was supplied to the client, typically by calling Request.sendResponse() or Request.sendError.
IOException - if there was an I/O error while sending the response to the client. Typically, in that case, the Server will (try to) send an error message to the client and then close the client's connection.

The IOException should not be used to silently ignore problems such as being unable to access some server-side resource (for example getting a FileNotFoundException due to not being able to open a file). In that case, the Handler's duty is to turn that IOException into a HTTP response indicating, in this case, that a file could not be found.

Version Kenai-svn-r24, Generated 08/18/09
Copyright (c) 2001-2009, Sun Microsystems.