Class DeferredHandler
- java.lang.Object
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- sunlabs.brazil.handler.DeferredHandler
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- All Implemented Interfaces:
Handler
public class DeferredHandler extends java.lang.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
- handler
- The token representing the handler to conditionally configure. This is used as the handler's prefix
- requires
- The names of classes required to be resolvable before configuring the handler
- [handler].prefix
- Used to trigger the configuration
- [handler].class
- The name of the handler class.
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Constructor Summary
Constructors Constructor Description DeferredHandler()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
init(Server server, java.lang.String prefix)
Remember the server for deferred initialization.boolean
respond(Request request)
Dispatch to the handler, installing it if needed
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Method Detail
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init
public boolean init(Server server, java.lang.String prefix)
Remember the server for deferred initialization.- Specified by:
init
in interfaceHandler
- Parameters:
server
- The HTTP server that created thisHandler
. TypicalHandler
s will useServer.props
to obtain run-time configuration information.prefix
- The handlers name. The string thisHandler
may prepend to all of the keys that it uses to extract configuration information fromServer.props
. This is set (by theServer
andChainHandler
) to help avoid configuration parameter namespace collisions.- Returns:
true
if thisHandler
initialized successfully,false
otherwise. Iffalse
is returned, thisHandler
should not be used.
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respond
public boolean respond(Request request) throws java.io.IOException
Dispatch to the handler, installing it if needed- Specified by:
respond
in interfaceHandler
- Parameters:
request
- TheRequest
object that represents the HTTP request.- Returns:
true
if the request was handled. A request was handled if a response was supplied to the client, typically by callingRequest.sendResponse()
orRequest.sendError
.- Throws:
java.io.IOException
- if there was an I/O error while sending the response to the client. Typically, in that case, theServer
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 aFileNotFoundException
due to not being able to open a file). In that case, theHandler
's duty is to turn thatIOException
into a HTTP response indicating, in this case, that a file could not be found.
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