org.springframework.boot.devtools.restart

Class Restarter

java.lang.Object

org.springframework.boot.devtools.restart.Restarter

public class Restarter
extends Object

Allows a running application to be restarted with an updated classpath. The restarter works by creating a new application ClassLoader that is split into two parts. The top part contains static URLs that don't change (for example 3rd party libraries and Spring Boot itself) and the bottom part contains URLs where classes and resources might be updated.

The Restarter should be initialized early to ensure that classes are loaded multiple times. Mostly the RestartApplicationListener can be relied upon to perform initialization, however, you may need to call initialize(String[]) directly if your SpringApplication arguments are not identical to your main method arguments.

By default, applications running in an IDE (i.e. those not packaged as "fat jars") will automatically detect URLs that can change. It's also possible to manually configure URLs or class file updates for remote restart scenarios.

Since:

1.3.0

Author:

Phillip Webb, Andy Wilkinson

See Also:

RestartApplicationListener, initialize(String[]), getInstance(), restart()

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Restarter(Thread thread, String[] args, boolean forceReferenceCleanup, RestartInitializer initializer) Internal constructor to create a new Restarter instance.

Method Summary

Modifier and Type	Method and Description
void	addClassLoaderFiles(ClassLoaderFiles classLoaderFiles) Add additional ClassLoaderFiles to be included in the next restart.
void	addUrls(Collection<URL> urls) Add additional URLs to be includes in the next restart.
static void	clearInstance() Clear the instance.
static void	disable() Initialize and disable restart support.
URL[]	getInitialUrls() Return the initial set of URLs as configured by the RestartInitializer.
static Restarter	getInstance() Return the active Restarter instance.
Object	getOrAddAttribute(String name, ObjectFactory<?> objectFactory)
ThreadFactory	getThreadFactory() Return a ThreadFactory that can be used to create leak safe threads.
protected void	initialize(boolean restartOnInitialize)
static void	initialize(String[] args) Initialize restart support.
static void	initialize(String[] args, boolean forceReferenceCleanup) Initialize restart support.
static void	initialize(String[] args, boolean forceReferenceCleanup, RestartInitializer initializer) Initialize restart support.
static void	initialize(String[] args, boolean forceReferenceCleanup, RestartInitializer initializer, boolean restartOnInitialize) Initialize restart support for the current application.
static void	initialize(String[] args, RestartInitializer initializer) Initialize restart support.
protected Throwable	relaunch(ClassLoader classLoader) Relaunch the application using the specified classloader.
Object	removeAttribute(String name)
void	restart() Restart the running application.
void	restart(FailureHandler failureHandler) Restart the running application.
protected void	start(FailureHandler failureHandler) Start the application.
protected void	stop() Stop the application.

Methods inherited from class java.lang.Object

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

Constructor Detail

Restarter

protected Restarter(Thread thread,
                    String[] args,
                    boolean forceReferenceCleanup,
                    RestartInitializer initializer)

Internal constructor to create a new Restarter instance.

Parameters:

thread - the source thread

args - the application arguments

forceReferenceCleanup - if soft/weak reference cleanup should be forced

initializer - the restart initializer

See Also:

initialize(String[])

Method Detail

initialize

protected void initialize(boolean restartOnInitialize)

addUrls

public void addUrls(Collection<URL> urls)

Add additional URLs to be includes in the next restart.

Parameters:

urls - the urls to add

addClassLoaderFiles

public void addClassLoaderFiles(ClassLoaderFiles classLoaderFiles)

Add additional ClassLoaderFiles to be included in the next restart.

Parameters:

classLoaderFiles - the files to add

getThreadFactory

public ThreadFactory getThreadFactory()

Return a ThreadFactory that can be used to create leak safe threads.

Returns:

a leak safe thread factory

restart

public void restart()

Restart the running application.

restart

public void restart(FailureHandler failureHandler)

Restart the running application.

Parameters:

failureHandler - a failure handler to deal with application that doesn't start

start

protected void start(FailureHandler failureHandler)
              throws Exception

Start the application.

Parameters:

failureHandler - a failure handler for application that won't start

Throws:

Exception - in case of errors

relaunch

protected Throwable relaunch(ClassLoader classLoader)
                      throws Exception

Relaunch the application using the specified classloader.

Parameters:

classLoader - the classloader to use

Returns:

any exception that caused the launch to fail or null

Throws:

Exception - in case of errors

stop

protected void stop()
             throws Exception

Stop the application.

Throws:

Exception - in case of errors

getOrAddAttribute

public Object getOrAddAttribute(String name,
                                ObjectFactory<?> objectFactory)

removeAttribute

public Object removeAttribute(String name)

getInitialUrls

public URL[] getInitialUrls()

Return the initial set of URLs as configured by the RestartInitializer.

Returns:

the initial URLs or null

disable

public static void disable()

Initialize and disable restart support.

initialize

public static void initialize(String[] args)

Initialize restart support. See initialize(String[], boolean, RestartInitializer) for details.

Parameters:

args - main application arguments

See Also:

initialize(String[], boolean, RestartInitializer)

initialize

public static void initialize(String[] args,
                              RestartInitializer initializer)

Initialize restart support. See initialize(String[], boolean, RestartInitializer) for details.

Parameters:

args - main application arguments

initializer - the restart initializer

See Also:

initialize(String[], boolean, RestartInitializer)

initialize

public static void initialize(String[] args,
                              boolean forceReferenceCleanup)

Initialize restart support. See initialize(String[], boolean, RestartInitializer) for details.

Parameters:

args - main application arguments

forceReferenceCleanup - if forcing of soft/weak reference should happen on

See Also:

initialize(String[], boolean, RestartInitializer)

initialize

public static void initialize(String[] args,
                              boolean forceReferenceCleanup,
                              RestartInitializer initializer)

Initialize restart support. See initialize(String[], boolean, RestartInitializer, boolean) for details.

Parameters:

args - main application arguments

forceReferenceCleanup - if forcing of soft/weak reference should happen on

initializer - the restart initializer

See Also:

initialize(String[], boolean, RestartInitializer)

initialize

public static void initialize(String[] args,
                              boolean forceReferenceCleanup,
                              RestartInitializer initializer,
                              boolean restartOnInitialize)

Initialize restart support for the current application. Called automatically by RestartApplicationListener but can also be called directly if main application arguments are not the same as those passed to the SpringApplication.

Parameters:

args - main application arguments

forceReferenceCleanup - if forcing of soft/weak reference should happen on each restart. This will slow down restarts and is intended primarily for testing

initializer - the restart initializer

restartOnInitialize - if the restarter should be restarted immediately when the RestartInitializer returns non null results

getInstance

public static Restarter getInstance()

Return the active Restarter instance. Cannot be called before initialization.

Returns:

the restarter

clearInstance

public static void clearInstance()

Clear the instance. Primarily provided for tests and not usually used in application code.