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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SynchronizedRequestHandler.ResponseWriter ResponseWriter is optionally returned by request handlers which implement synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse, String) The ResponseWriter will be executed by handleRequest(VaadinSession, VaadinRequest, VaadinResponse) without holding Vaadin session lock.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_BUFFER_SIZE

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.
static long	getMaxRequestBodySize(VaadinRequest request) Gets the configured maximum request body size for the given request, in characters.
static String	getRequestBody(Reader reader) Reads the entire request body from the given reader without any size limit.
static String	getRequestBody(Reader reader, long maxBodySize) Reads the request body from the given reader, rejecting it once it exceeds maxBodySize characters.
boolean	handleRequest(VaadinSession session, VaadinRequest request, VaadinResponse response) Called when a request needs to be handled.
boolean	isReadAndWriteOutsideSessionLock() Gets if request body should be read and the response written without holding VaadinSession lock
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.
Optional<SynchronizedRequestHandler.ResponseWriter>	synchronizedHandleRequest(VaadinSession session, VaadinRequest request, VaadinResponse response, String requestBody) Identical to synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse) except the VaadinSession is locked before this is called and the response requestBody has been read before locking the session and is provided as a separate parameter.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_BUFFER_SIZE

public static final int MAX_BUFFER_SIZE

See Also:

Constant Field Values

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)

isReadAndWriteOutsideSessionLock

public boolean isReadAndWriteOutsideSessionLock()

Gets if request body should be read and the response written without holding VaadinSession lock

Returns:

true if synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse, String) should be called. Returns false if synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse) should be called.

synchronizedHandleRequest

public Optional<SynchronizedRequestHandler.ResponseWriter> synchronizedHandleRequest(VaadinSession session,
                                                                                     VaadinRequest request,
                                                                                     VaadinResponse response,
                                                                                     String requestBody)
                                                                              throws IOException,
                                                                                     UnsupportedOperationException

Identical to synchronizedHandleRequest(VaadinSession, VaadinRequest, VaadinResponse) except the VaadinSession is locked before this is called and the response requestBody has been read before locking the session and is provided as a separate parameter.

Parameters:

session - The session for the request

request - The request to handle

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

requestBody - Request body pre-read from the request object

Returns:

a ResponseWriter wrapped into an Optional, if this handler will write the response and no further request handlers should be called, otherwise an empty Optional. The ResponseWriter will be executed after the VaadinSession is unlocked.

Throws:

IOException - If an IO error occurred

UnsupportedOperationException

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.

getRequestBody

public static String getRequestBody(Reader reader)
                             throws IOException

Reads the entire request body from the given reader without any size limit.

Prefer getRequestBody(Reader, long) on request-handling code paths so that the configured maximum request body size is enforced.

Parameters:

reader - the reader to read the request body from

Returns:

the request body as a string

Throws:

IOException - if reading fails

getRequestBody

public static String getRequestBody(Reader reader,
                                    long maxBodySize)
                             throws IOException

Reads the request body from the given reader, rejecting it once it exceeds maxBodySize characters.

The limit is enforced on the number of characters read from the reader. For typical ASCII/UTF-8 JSON payloads this equals the number of bytes; multi-byte content makes the effective byte limit larger.

Parameters:

reader - the reader to read the request body from

maxBodySize - the maximum number of characters to read, or a negative number to read without any limit

Returns:

the request body as a string

Throws:

IOException - if reading fails

RequestBodyTooLargeException - if the body exceeds maxBodySize characters

getMaxRequestBodySize

public static long getMaxRequestBodySize(VaadinRequest request)

Gets the configured maximum request body size for the given request, in characters.

Parameters:

request - the request being handled

Returns:

the maximum request body size in characters, or a negative number if the limit is disabled