VaadinSession (Vaadin Platform (vaadin-platform-javadoc) 22.0.26 API)

java.lang.Object
- com.vaadin.flow.server.VaadinSession

All Implemented Interfaces:

Serializable, EventListener, javax.servlet.http.HttpSessionBindingListener
```
public class VaadinSession
extends Object
implements javax.servlet.http.HttpSessionBindingListener, Serializable
```
Contains everything that Vaadin needs to store for a specific user. This is typically stored in a HttpSession, but others storage mechanisms might also be used.
Everything inside a VaadinSession should be serializable to ensure compatibility with schemes using serialization for persisting the session data.
Current VaadinSession object which can be accessed by getCurrent() is not present before VaadinServlet starts handling the HTTP request. For example, it cannot be used in any implementation of Filter interface.

Since:

1.0

Author:

Vaadin Ltd

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

protected WebBrowser browser

static String UI_PARAMETER
Deprecated.
Use InitParameters.UI_PARAMETER instead.

Fields
Modifier and Type	Field and Description
`protected WebBrowser`	`browser`
`static String`	`UI_PARAMETER` Deprecated. Use `InitParameters.UI_PARAMETER` instead.

Constructor Summary

Constructors
Constructor and Description

VaadinSession(VaadinService service)
Creates a new VaadinSession tied to a VaadinService.

Constructors
Constructor and Description
`VaadinSession(VaadinService service)` Creates a new VaadinSession tied to a VaadinService.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Future<Void>`	`access(Command command)` Provides exclusive access to this session from outside a request handling thread.
`void`	`accessSynchronously(Command command)` Locks this session and runs the provided Command right away.
`void`	`addRequestHandler(RequestHandler handler)` Adds a request handler to this session.
`void`	`addUI(UI ui)` Adds an initialized UI to this session.
`void`	`checkHasLock()` Potentially checks whether this session is currently locked by the current thread, and fails with a standard error message if not.
`void`	`checkHasLock(String message)` Potentially checks whether this session is currently locked by the current thread, and fails with the given message if not.
`void`	`close()` Sets this session to be closed and all UI state to be discarded at the end of the current request, or at the end of the next request if there is no ongoing one.
`protected StreamResourceRegistry`	`createStreamResourceRegistry()` Creates the StreamResourceRegistry for this session.
`static Collection<VaadinSession>`	`getAllSessions(javax.servlet.http.HttpSession httpSession)` Retrieves all `VaadinSession`s which are stored in the given HTTP session.
`<T> T`	`getAttribute(Class<T> type)` Gets a stored attribute value.
`Object`	`getAttribute(String name)` Gets a stored attribute value.
`WebBrowser`	`getBrowser()` Get the web browser associated with this session.
`DeploymentConfiguration`	`getConfiguration()` Gets the configuration for this session.
`long`	`getCumulativeRequestDuration()`
`static VaadinSession`	`getCurrent()` Gets the currently used session.
`ErrorHandler`	`getErrorHandler()` Gets the session's error handler.
`long`	`getLastLocked()` Gets the timestamp of the most recent lock operation performed on this session.
`long`	`getLastRequestDuration()`
`long`	`getLastRequestTimestamp()` Returns the time when the last request was serviced in this session.
`long`	`getLastUnlocked()` Gets the timestamp of the most recent unlock operation performed on this session.
`Locale`	`getLocale()` Gets the locale for this session.
`Lock`	`getLockInstance()` Gets the `Lock` instance that is used for protecting the data of this session from concurrent access.
`int`	`getNextUIid()` Creates a new unique id for a UI.
`Queue<FutureAccess>`	`getPendingAccessQueue()` Gets the queue of tasks submitted using `access(Command)`.
`String`	`getPushId()` Gets the push connection identifier for this session.
`Collection<RequestHandler>`	`getRequestHandlers()` Gets the request handlers that are registered to the session.
`StreamResourceRegistry`	`getResourceRegistry()` Get resource registry instance.
`VaadinService`	`getService()`
`WrappedSession`	`getSession()` Gets the underlying session to which this service session is currently associated.
`VaadinSessionState`	`getState()` Returns the lifecycle state of this session.
`UI`	`getUIById(int uiId)` Returns a UI with the given id.
`Collection<UI>`	`getUIs()` Gets all the UIs of this session.
`boolean`	`hasLock()` Checks if the current thread has exclusive access to this `VaadinSession`.
`protected static boolean`	`hasLock(VaadinService service, WrappedSession session)` Checks if the current thread has exclusive access to the given WrappedSession.
`void`	`lock()` Locks this session to protect its data from concurrent access.
`void`	`refreshTransients(WrappedSession wrappedSession, VaadinService vaadinService)` Refreshes the transient fields of the session to ensure they are up to date.
`void`	`removeRequestHandler(RequestHandler handler)` Removes a request handler from the session.
`void`	`removeUI(UI ui)` Called by the framework to remove an UI instance from the session because it has been closed.
`<T> void`	`setAttribute(Class<T> type, T value)` Stores a value in this service session.
`void`	`setAttribute(String name, Object value)` Stores a value in this service session.
`void`	`setBrowser(WebBrowser browser)` Set the web browser associated with this session.
`void`	`setConfiguration(DeploymentConfiguration configuration)`
`static void`	`setCurrent(VaadinSession session)` Sets the thread local for the current session.
`void`	`setErrorHandler(ErrorHandler errorHandler)` Sets the session error handler.
`void`	`setLastRequestDuration(long time)` Sets the time spent servicing the last request in the session and updates the total time spent servicing requests in this session.
`void`	`setLastRequestTimestamp(long timestamp)` Sets the time when the last UIDL request was serviced in this session.
`void`	`setLocale(Locale locale)` Sets the default locale for this session.
`protected void`	`setState(VaadinSessionState state)` Sets the lifecycle state of this session.
`void`	`unlock()` Unlocks this session.
`void`	`valueBound(javax.servlet.http.HttpSessionBindingEvent arg0)`
`void`	`valueUnbound(javax.servlet.http.HttpSessionBindingEvent event)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - UI_PARAMETER
```
@Deprecated
public static final String UI_PARAMETER
```
    Deprecated. Use InitParameters.UI_PARAMETER instead.
    
    See Also:
    
    Constant Field Values
  - browser
```
protected WebBrowser browser
```
- Constructor Detail
  - VaadinSession
```
public VaadinSession(VaadinService service)
```
    Creates a new VaadinSession tied to a VaadinService.
    
    Parameters:
    
    service - the Vaadin service for the new session
- Method Detail
  - createStreamResourceRegistry
```
protected StreamResourceRegistry createStreamResourceRegistry()
```
    Creates the StreamResourceRegistry for this session.
    
    Returns:
    
    A StreamResourceRegistry instance
  - valueBound
```
public void valueBound(javax.servlet.http.HttpSessionBindingEvent arg0)
```
    Specified by:
    
    valueBound in interface javax.servlet.http.HttpSessionBindingListener
    
    See Also:
    
    HttpSessionBindingListener.valueBound(HttpSessionBindingEvent)
  - valueUnbound
```
public void valueUnbound(javax.servlet.http.HttpSessionBindingEvent event)
```
    Specified by:
    
    valueUnbound in interface javax.servlet.http.HttpSessionBindingListener
    
    See Also:
    
    HttpSessionBindingListener.valueUnbound(HttpSessionBindingEvent)
  - getBrowser
```
public WebBrowser getBrowser()
```
    Get the web browser associated with this session.
    
    Returns:
    
    the web browser object
  - setBrowser
```
public void setBrowser(WebBrowser browser)
```
    Set the web browser associated with this session.
    
    Parameters:
    
    browser - the web browser object
  - getCumulativeRequestDuration
```
public long getCumulativeRequestDuration()
```
    Returns:
    
    The total time spent servicing requests in this session, in milliseconds.
  - setLastRequestDuration
```
public void setLastRequestDuration(long time)
```
    Sets the time spent servicing the last request in the session and updates the total time spent servicing requests in this session.
    
    Parameters:
    
    time - The time spent in the last request, in milliseconds.
  - getLastRequestDuration
```
public long getLastRequestDuration()
```
    Returns:
    
    The time spent servicing the last request in this session, in milliseconds.
  - setLastRequestTimestamp
```
public void setLastRequestTimestamp(long timestamp)
```
    Sets the time when the last UIDL request was serviced in this session.
    
    Parameters:
    
    timestamp - The time when the last request was handled, in milliseconds since the epoch.
  - getLastRequestTimestamp
```
public long getLastRequestTimestamp()
```
    Returns the time when the last request was serviced in this session.
    
    Returns:
    
    The time when the last request was handled, in milliseconds since the epoch.
  - getSession
```
public WrappedSession getSession()
```
    Gets the underlying session to which this service session is currently associated.
    
    Returns:
    
    the wrapped session for this context
  - getAllSessions
```
public static Collection<VaadinSession> getAllSessions(javax.servlet.http.HttpSession httpSession)
```
    Retrieves all VaadinSessions which are stored in the given HTTP session.
    
    Parameters:
    
    httpSession - the HTTP session
    
    Returns:
    
    the found VaadinSessions
  - setConfiguration
```
public void setConfiguration(DeploymentConfiguration configuration)
```
  - getConfiguration
```
public DeploymentConfiguration getConfiguration()
```
    Gets the configuration for this session.
    
    Returns:
    
    the deployment configuration
  - getLocale
```
public Locale getLocale()
```
    Gets the locale for this session.
    The default locale is determined in different ways depending on whether a I18NProvider is available.
    If a i18n provider is available, the locale is determined by selecting the locale from I18NProvider.getProvidedLocales() that best matches the user agent preferences (i.e. the Accept-Language header). If an exact match is found, then that locale is used. Otherwise, the matching logic looks for the first provided locale that uses the same language regardless of the country. If no other match is found, then the first item from I18NProvider.getProvidedLocales() is used.
    If no i18n provider is available, then the default JVM locale is used as the default locale.
    
    Returns:
    
    the locale of this session.
  - setLocale
```
public void setLocale(Locale locale)
```
    Sets the default locale for this session.
    Setting the locale of a session will also override any custom locale configured for all UIs in this session.
    
    Parameters:
    
    locale - the locale to set, not null
  - getErrorHandler
```
public ErrorHandler getErrorHandler()
```
    Gets the session's error handler.
    
    Returns:
    
    the current error handler
  - setErrorHandler
```
public void setErrorHandler(ErrorHandler errorHandler)
```
    Sets the session error handler.
    
    Parameters:
    
    errorHandler - the new error handler, not null
  - addRequestHandler
```
public void addRequestHandler(RequestHandler handler)
```
    Adds a request handler to this session. Request handlers can be added to provide responses to requests that are not handled by the default functionality of the framework.
    Handlers are called in reverse order of addition, so the most recently added handler will be called first.
    
    Parameters:
    
    handler - the request handler to add
    
    See Also:
    
    removeRequestHandler(RequestHandler)
  - removeRequestHandler
```
public void removeRequestHandler(RequestHandler handler)
```
    Removes a request handler from the session.
    
    Parameters:
    
    handler - the request handler to remove
  - getRequestHandlers
```
public Collection<RequestHandler> getRequestHandlers()
```
    Gets the request handlers that are registered to the session. The iteration order of the returned collection is the same as the order in which the request handlers will be invoked when a request is handled.
    
    Returns:
    
    a collection of request handlers, with the iteration order according to the order they would be invoked
    
    See Also:
    
    addRequestHandler(RequestHandler), removeRequestHandler(RequestHandler)
  - getCurrent
```
public static VaadinSession getCurrent()
```
    Gets the currently used session. The current session is automatically defined when processing requests to the server (see ThreadLocal) and in access(Command) and UI.access(Command). In other cases, (e.g. from background threads), the current session is not automatically defined.
    The session is stored using a weak reference to avoid leaking memory in case it is not explicitly cleared.
    
    Returns:
    
    the current session instance if available, otherwise null
    
    See Also:
    
    setCurrent(VaadinSession)
  - setCurrent
```
public static void setCurrent(VaadinSession session)
```
    Sets the thread local for the current session. This method is used by the framework to set the current session whenever a new request is processed and it is cleared when the request has been processed.
    The application developer can also use this method to define the current session outside the normal request handling and treads started from request handling threads, e.g. when initiating custom background threads.
    The session is stored using a weak reference to avoid leaking memory in case it is not explicitly cleared.
    
    Parameters:
    
    session - the session to set as current
    
    See Also:
    
    getCurrent(), ThreadLocal
  - getUIs
```
public Collection<UI> getUIs()
```
    Gets all the UIs of this session. This includes UIs that have been requested but not yet initialized. UIs that receive no heartbeat requests from the client are eventually removed from the session.
    
    Returns:
    
    a collection of UIs belonging to this application
  - getUIById
```
public UI getUIById(int uiId)
```
    Returns a UI with the given id.
    This is meant for framework internal use.
    
    Parameters:
    
    uiId - The UI id
    
    Returns:
    
    The UI with the given id or null if not found
  - hasLock
```
public boolean hasLock()
```
    Checks if the current thread has exclusive access to this VaadinSession.
    
    Returns:
    
    true if the thread has exclusive access, false otherwise
  - checkHasLock
```
public void checkHasLock(String message)
```
    Potentially checks whether this session is currently locked by the current thread, and fails with the given message if not.
    When production mode is enabled, the check is only done if assertions are also enabled. This is done to avoid the small performance impact of continuously checking the lock status. The check is always done when production mode is not enabled.
    
    Parameters:
    
    message - the error message to include when failing if the check is done and the session is not locked
  - checkHasLock
```
public void checkHasLock()
```
    Potentially checks whether this session is currently locked by the current thread, and fails with a standard error message if not.
    When production mode is enabled, the check is only done if assertions are also enabled. This is done to avoid the small performance impact of continuously checking the lock status. The check is always done when production mode is not enabled.
  - hasLock
```
protected static boolean hasLock(VaadinService service,
                                 WrappedSession session)
```
    Checks if the current thread has exclusive access to the given WrappedSession.
    
    Parameters:
    
    service - the service to check
    
    session - the session to use for checking
    
    Returns:
    
    true if this thread has exclusive access, false otherwise
  - removeUI
```
public void removeUI(UI ui)
```
    Called by the framework to remove an UI instance from the session because it has been closed.
    
    Parameters:
    
    ui - the UI to remove
  - getLockInstance
```
public Lock getLockInstance()
```
    Gets the Lock instance that is used for protecting the data of this session from concurrent access.
    The Lock can be used to gain more control than what is available only using lock() and unlock(). The returned instance is not guaranteed to support any other features of the Lock interface than Lock.lock() and Lock.unlock().
    
    Returns:
    
    the Lock that is used for synchronization, it's never null for the session which is in use, i.e. if refreshTransients(WrappedSession, VaadinService) has been called for it
    
    See Also:
    
    lock(), Lock
  - lock
```
public void lock()
```
    Locks this session to protect its data from concurrent access. Accessing the UI state from outside the normal request handling should always lock the session and unlock it when done. The preferred way to ensure locking is done correctly is to wrap your code using UI.access(Command) (or access(Command) if you are only touching the session and not any UI), e.g.:
```
 myUI.access(new Command() {
     @Override
     public void run() {
         // Here it is safe to update the UI.
         // UI.getCurrent can also be used
         myUI.getContent().setCaption("Changed safely");
     }
 });
 
```
    If you for whatever reason want to do locking manually, you should do it like:
```
 session.lock();
 try {
     doSomething();
 } finally {
     session.unlock();
 }
 
```
    This method will block until the lock can be retrieved.
    getLockInstance() can be used if more control over the locking is required.
    See Also:
    
    unlock(), getLockInstance(), hasLock()
  - unlock
```
public void unlock()
```
    Unlocks this session. This method should always be used in a finally block after lock() to ensure that the lock is always released.
    For UIs in this session that have its push mode set to automatic, pending changes will be pushed to their respective clients.
    
    See Also:
    
    lock(), UI.push()
  - setAttribute
```
public void setAttribute(String name,
                         Object value)
```
    Stores a value in this service session. This can be used to associate data with the current user so that it can be retrieved at a later point from some other part of the application. Setting the value to null clears the stored value.
    
    Parameters:
    
    name - the name to associate the value with, can not be null
    
    value - the value to associate with the name, or null to remove a previous association.
    
    See Also:
    
    getAttribute(String)
  - setAttribute
```
public <T> void setAttribute(Class<T> type,
                             T value)
```
    Stores a value in this service session. This can be used to associate data with the current user so that it can be retrieved at a later point from some other part of the application. Setting the value to null clears the stored value.
    The fully qualified name of the type is used as the name when storing the value. The outcome of calling this method is thus the same as if calling
    setAttribute(type.getName(), value);
    
    Type Parameters:
    
    T - the type of the stored value
    
    Parameters:
    
    type - the type that the stored value represents, can not be null
    
    value - the value to associate with the type, or null to remove a previous association.
    
    See Also:
    
    getAttribute(Class), setAttribute(String, Object)
  - getAttribute
```
public Object getAttribute(String name)
```
    Gets a stored attribute value. If a value has been stored for the session, that value is returned. If no value is stored for the name, null is returned.
    
    Parameters:
    
    name - the name of the value to get, can not be null.
    
    Returns:
    
    the value, or null if no value has been stored or if it has been set to null.
    
    See Also:
    
    setAttribute(String, Object)
  - getAttribute
```
public <T> T getAttribute(Class<T> type)
```
    Gets a stored attribute value. If a value has been stored for the session, that value is returned. If no value is stored for the name, null is returned.
    The fully qualified name of the type is used as the name when getting the value. The outcome of calling this method is thus the same as if calling
    
    getAttribute(type.getName());
    
    Type Parameters:
    
    T - the type of the value to get
    
    Parameters:
    
    type - the type of the value to get, can not be null.
    
    Returns:
    
    the value, or null if no value has been stored or if it has been set to null.
    
    See Also:
    
    setAttribute(Class, Object), getAttribute(String)
  - getNextUIid
```
public int getNextUIid()
```
    Creates a new unique id for a UI.
    
    Returns:
    
    a unique UI id
  - addUI
```
public void addUI(UI ui)
```
    Adds an initialized UI to this session.
    
    Parameters:
    
    ui - the initialized UI to add.
  - getService
```
public VaadinService getService()
```
  - close
```
public void close()
```
    Sets this session to be closed and all UI state to be discarded at the end of the current request, or at the end of the next request if there is no ongoing one.
    After the session has been discarded, any UIs that have been left open will give a Session Expired error and a new session will be created for serving new UIs.
    Note that this method only closes the VaadinSession which is not the same as HttpSession. To invalidate the underlying HTTP session getSession().invalidate(); needs to be called.
    The method is usually called to perform logout. If user data is stored inside HTTP session then getSession().invalidate(); should be called instead (most common case). It makes sense to call close() only if user data is stored inside a VaadinSession. Use the Page.setLocation(String) method to navigate to some page after session is closed to avoid session expired message.
    
    See Also:
    
    SystemMessages.getSessionExpiredCaption()
  - getState
```
public VaadinSessionState getState()
```
    Returns the lifecycle state of this session.
    
    Returns:
    
    the current state
  - setState
```
protected void setState(VaadinSessionState state)
```
    Sets the lifecycle state of this session. The allowed transitions are OPEN to CLOSING and CLOSING to CLOSED.
    
    Parameters:
    
    state - the new state
  - accessSynchronously
```
public void accessSynchronously(Command command)
```
    Locks this session and runs the provided Command right away.
    It is generally recommended to use access(Command) instead of this method for accessing a session from a different thread as access(Command) can be used while holding the lock of another session. To avoid causing deadlocks, this methods throws an exception if it is detected than another session is also locked by the current thread.
    This method behaves differently than access(Command) in some situations:
    - If the current thread is currently holding the lock of this session, accessSynchronously(Command) runs the task right away whereas access(Command) defers the task to a later point in time.
    - If some other thread is currently holding the lock for this session, accessSynchronously(Command) blocks while waiting for the lock to be available whereas access(Command) defers the task to a later point in time.
    Parameters:
    
    command - the command which accesses the session
    
    Throws:
    
    IllegalStateException - if the current thread holds the lock for another session
    
    See Also:
    
    lock(), getCurrent(), access(Command), UI.accessSynchronously(Command)
  - access
```
public Future<Void> access(Command command)
```
    Provides exclusive access to this session from outside a request handling thread.
    The given command is executed while holding the session lock to ensure exclusive access to this session. If this session is not locked, the lock will be acquired and the command is run right away. If this session is currently locked, the command will be run before that lock is released.
    RPC handlers for components inside this session do not need to use this method as the session is automatically locked by the framework during RPC handling.
    Please note that the command might be invoked on a different thread or later on the current thread, which means that custom thread locals might not have the expected values when the command is executed. getCurrent() and VaadinService.getCurrent() are set according to this session before executing the command. Other standard CurrentInstance values such as VaadinService.getCurrentRequest() and VaadinService.getCurrentResponse() will not be defined.
    The returned future can be used to check for task completion and to cancel the task. To help avoiding deadlocks, Future.get() throws an exception if it is detected that the current thread holds the lock for some other session.
    
    Parameters:
    
    command - the command which accesses the session
    
    Returns:
    
    a future that can be used to check for task completion and to cancel the task
    
    See Also:
    
    lock(), getCurrent(), accessSynchronously(Command), UI.access(Command)
  - getPendingAccessQueue
```
public Queue<FutureAccess> getPendingAccessQueue()
```
    Gets the queue of tasks submitted using access(Command). It is safe to call this method and access the returned queue without holding the session lock.
    
    Returns:
    
    the queue of pending access tasks
  - getPushId
```
public String getPushId()
```
    Gets the push connection identifier for this session. Used when establishing a push connection with the client.
    
    Returns:
    
    the push connection identifier string
  - refreshTransients
```
public void refreshTransients(WrappedSession wrappedSession,
                              VaadinService vaadinService)
```
    Refreshes the transient fields of the session to ensure they are up to date.
    Called internally by the framework.
    
    Parameters:
    
    wrappedSession - the session this VaadinSession is stored in
    
    vaadinService - the service associated with this VaadinSession
  - getResourceRegistry
```
public StreamResourceRegistry getResourceRegistry()
```
    Get resource registry instance.
    Use this instance to manage StreamResources.
    
    Returns:
    
    resource registry
  - getLastLocked
```
public long getLastLocked()
```
    Gets the timestamp of the most recent lock operation performed on this session. Value is expressed as the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    
    Returns:
    
    last lock operation timestamp.
  - getLastUnlocked
```
public long getLastUnlocked()
```
    Gets the timestamp of the most recent unlock operation performed on this session. Value is expressed as the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    
    Returns:
    
    last unlock operation timestamp.

Class VaadinSession

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

UI_PARAMETER

browser

Constructor Detail

VaadinSession

Method Detail

createStreamResourceRegistry

valueBound

valueUnbound

getBrowser

setBrowser

getCumulativeRequestDuration

setLastRequestDuration

getLastRequestDuration

setLastRequestTimestamp

getLastRequestTimestamp

getSession

getAllSessions

setConfiguration

getConfiguration

getLocale

setLocale

getErrorHandler

setErrorHandler

addRequestHandler

removeRequestHandler

getRequestHandlers

getCurrent

setCurrent

getUIs

getUIById

hasLock

checkHasLock

checkHasLock

hasLock

removeUI

getLockInstance

lock

unlock

setAttribute

setAttribute

getAttribute

getAttribute

getNextUIid

addUI

getService

close

getState

setState

accessSynchronously

access

getPendingAccessQueue

getPushId

refreshTransients

getResourceRegistry

getLastLocked

getLastUnlocked