Package com.vaadin.base.devserver.hotswap

Class Hotswapper

java.lang.Object

com.vaadin.base.devserver.hotswap.Hotswapper

All Implemented Interfaces:

com.vaadin.flow.server.ServiceDestroyListener, com.vaadin.flow.server.SessionDestroyListener, com.vaadin.flow.server.SessionInitListener, com.vaadin.flow.server.UIInitListener, Serializable

public class Hotswapper
extends Object
implements com.vaadin.flow.server.ServiceDestroyListener, com.vaadin.flow.server.SessionInitListener, com.vaadin.flow.server.SessionDestroyListener, com.vaadin.flow.server.UIInitListener

Entry point for application classes hot reloads.

This class is meant to be used in combination with class live reloading tools like JRebel, Hotswap agent and Spring Boot Developer Tools, to immediately apply changes on components that should be updated when classes have been added or modified. Currently, class deletion is not supported because of issues with several hotswap agents.

Hotswap tools should obtain an instance of this class by calling the register(VaadinService) method, providing an active VaadinService instance. For example, an agent can inject the following code at the beginning of the VaadinService.init() method:

 
 com.vaadin.flow.hotswap.Hotswapper.register(this);
 
 

The component delegates specific hotswap logic to registered implementors of VaadinHotswapper interface.

By default, Hotswapper determines the best browser page refresh strategy, but a full page reload can be forced by setting the vaadin.hotswap.forcePageReload system property. Hotswap tools can alter the behavior at runtime by calling forcePageReload(VaadinService, boolean)

For internal use only. May be renamed or removed in a future release.

Since:

24.5

Author:

Vaadin Ltd

See Also:

• VaadinHotswapper
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final String	FORCE_RELOAD_PROPERTY	Configuration name for the system parameter that determines whether Hotswapper should always trigger a full page reload instead of computing an appropriate UI refresh strategy.

Method Summary

Modifier and Type	Method	Description
static void	forcePageReload(com.vaadin.flow.server.VaadinService vaadinService, boolean forceReload)	Instructs the Hotswapper if a full page reload should always be triggered instead of detecting the best UI refresh strategy.
static boolean	isForcedPageReload(com.vaadin.flow.server.VaadinService vaadinService)	Gets whether a forced full page reload is triggered on class changes.
void	onHotswap(String[] classes, Boolean redefined)	Called by hotswap tools when one or more application classes have been updated.
void	onHotswap(URI[] createdResources, URI[] modifiedResources, URI[] deletedResources)	Called by hotswap tools when one or more application resources have been changed.
static Optional<Hotswapper>	register(com.vaadin.flow.server.VaadinService vaadinService)	Register the hotwsapper entry point for the given VaadinService.
void	serviceDestroy(com.vaadin.flow.server.ServiceDestroyEvent event)
void	sessionDestroy(com.vaadin.flow.server.SessionDestroyEvent event)
void	sessionInit(com.vaadin.flow.server.SessionInitEvent event)
void	uiInit(com.vaadin.flow.server.UIInitEvent event)

Methods inherited from class java.lang.Object

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

Field Details

FORCE_RELOAD_PROPERTY

public static final String FORCE_RELOAD_PROPERTY

Configuration name for the system parameter that determines whether Hotswapper should always trigger a full page reload instead of computing an appropriate UI refresh strategy.

See Also:

• Constant Field Values

Method Details

onHotswap

public void onHotswap(String[] classes,
 Boolean redefined)

Called by hotswap tools when one or more application classes have been updated.

This method delegates update operations to registered VaadinHotswapper implementors. invoking first VaadinHotswapper.onClassesChange(HotswapClassEvent) and then invoking VaadinHotswapper.onClassesChange(HotswapClassSessionEvent) for each active VaadinSession.

Parameters:

classes - the set of affected classes.

redefined - true if the classes have been redefined by hotswap mechanism, false if they have been loaded for time by the ClassLoader.

See Also:

• VaadinHotswapper.onClassesChange(HotswapClassEvent)
• VaadinHotswapper.onClassesChange(HotswapClassSessionEvent)

onHotswap

public void onHotswap(URI[] createdResources,
 URI[] modifiedResources,
 URI[] deletedResources)

Called by hotswap tools when one or more application resources have been changed.

Parameters:

createdResources - the list of potentially newly created resources. Never null.

modifiedResources - the list of potentially modified resources. Never null.

deletedResources - the list of potentially deleted resource. Never null.

sessionInit

public void sessionInit(com.vaadin.flow.server.SessionInitEvent event)
                 throws com.vaadin.flow.server.ServiceException

Specified by:

sessionInit in interface com.vaadin.flow.server.SessionInitListener

Throws:

com.vaadin.flow.server.ServiceException

sessionDestroy

public void sessionDestroy(com.vaadin.flow.server.SessionDestroyEvent event)

Specified by:

sessionDestroy in interface com.vaadin.flow.server.SessionDestroyListener

serviceDestroy

public void serviceDestroy(com.vaadin.flow.server.ServiceDestroyEvent event)

Specified by:

serviceDestroy in interface com.vaadin.flow.server.ServiceDestroyListener

uiInit

public void uiInit(com.vaadin.flow.server.UIInitEvent event)

Specified by:

uiInit in interface com.vaadin.flow.server.UIInitListener

register

public static Optional<Hotswapper> register(com.vaadin.flow.server.VaadinService vaadinService)

Register the hotwsapper entry point for the given VaadinService.

The hotswapper is registered only in development mode.

Parameters:

vaadinService - the VaadinService instance for hotswapper registration.

Returns:

the hotswapper instance wrapped into an Optional, or an empty Optional if Vaadin is running in production mode.

forcePageReload

public static void forcePageReload(com.vaadin.flow.server.VaadinService vaadinService,
 boolean forceReload)

Instructs the Hotswapper if a full page reload should always be triggered instead of detecting the best UI refresh strategy.

Parameters:

vaadinService - the VaadinService instance.

forceReload - true to always force a page reload, false to let the Hotswapper decide the refresh strategy.

isForcedPageReload

public static boolean isForcedPageReload(com.vaadin.flow.server.VaadinService vaadinService)

Gets whether a forced full page reload is triggered on class changes.

Parameters:

vaadinService - the VaadinService instance.

Returns:

true if full page reload if forced, otherwise false.