com.vaadin.flow.server

Class SynchronizedRequestHandler

java.lang.Object

com.vaadin.flow.server.SynchronizedRequestHandler

All Implemented Interfaces:

RequestHandler, Serializable

Direct Known Subclasses:

BootstrapHandler, HeartbeatHandler, UidlRequestHandler, UnsupportedBrowserHandler, WebComponentProvider

public abstract class SynchronizedRequestHandler
extends Object
implements RequestHandler

RequestHandler which takes care of locking and unlocking of the VaadinSession automatically. The session is locked before synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse) is called and unlocked after it has completed.

Since:

1.0

Author:

Vaadin Ltd

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
SynchronizedRequestHandler()

Method Summary

Modifier and Type	Method and Description
protected boolean	canHandleRequest(VaadinRequest request) Check whether a request may be handled by this handler.
boolean	handleRequest(VaadinSession session, VaadinRequest request, VaadinResponse response) Called when a request needs to be handled.
abstract boolean	synchronizedHandleRequest(VaadinSession session, VaadinRequest request, VaadinResponse response) Identical to handleRequest(VaadinSession, VaadinRequest, VaadinResponse) except the VaadinSession is locked before this is called and unlocked after this has completed.

Methods inherited from class java.lang.Object

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

Constructor Detail

SynchronizedRequestHandler

public SynchronizedRequestHandler()

Method Detail

handleRequest

public boolean handleRequest(VaadinSession session,
                             VaadinRequest request,
                             VaadinResponse response)
                      throws IOException

Description copied from interface: RequestHandler

Called when a request needs to be handled. If a response is written, this method should return true to indicate that no more request handlers should be invoked for the request.

Note that request handlers by default do not lock the session. If you are using VaadinSession or anything inside the VaadinSession you must ensure the session is locked. This can be done by extending SynchronizedRequestHandler or by using VaadinSession.accessSynchronously(Command) or UI.accessSynchronously(Command).

Specified by:

handleRequest in interface RequestHandler

Parameters:

session - The session for the request

request - The request to handle

response - The response object to which a response can be written.

Returns:

true if a response has been written and no further request handlers should be called, otherwise false

Throws:

IOException - If an IO error occurred

synchronizedHandleRequest

public abstract boolean synchronizedHandleRequest(VaadinSession session,
                                                  VaadinRequest request,
                                                  VaadinResponse response)
                                           throws IOException

Identical to handleRequest(VaadinSession, VaadinRequest, VaadinResponse) except the VaadinSession is locked before this is called and unlocked after this has completed.

Parameters:

session - The session for the request

request - The request to handle

response - The response object to which a response can be written.

Returns:

true if a response has been written and no further request handlers should be called, otherwise false

Throws:

IOException - If an IO error occurred

See Also:

handleRequest(VaadinSession, VaadinRequest, VaadinResponse)

canHandleRequest

protected boolean canHandleRequest(VaadinRequest request)

Check whether a request may be handled by this handler. This can be used as an optimization to avoid locking the session just to investigate some method property. The default implementation just returns true which means that all requests will be handled by calling synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse) with the session locked.

Parameters:

request - the request to handle

Returns:

true if the request handling should continue once the session has been locked; false if there's no need to lock the session since the request would still not be handled.