com.atlassian.johnson.spring.web.context

Class JohnsonContextLoaderListener

java.lang.Object

org.springframework.web.context.ContextLoader

org.springframework.web.context.ContextLoaderListener

com.atlassian.johnson.spring.web.context.JohnsonContextLoaderListener

All Implemented Interfaces:

EventListener, javax.servlet.ServletContextListener

public class JohnsonContextLoaderListener
extends org.springframework.web.context.ContextLoaderListener

Extends the standard Spring ContextLoaderListener to make it Johnson-aware. When using this class, if the Spring context fails to start an event will added to Johnson rather than propagated to the servlet container.

The goal of this class is to prevent the web application from being shutdown if Spring cannot be started. By default, if the WebApplicationContext cannot be started for any reason, an exception is thrown which is propagated up to the container. When this happens, the entire web application is terminated. This precludes the use of Johnson, which requires that the web application be up so that it can serve its status pages.

Field Summary

Fields

Modifier and Type	Field and Description
static String	ATTR_BYPASSED The attribute added to the ServletContext when Spring context initialization is bypassed because a previous Event indicates the application has already failed.

Fields inherited from class org.springframework.web.context.ContextLoader

CONFIG_LOCATION_PARAM, CONTEXT_CLASS_PARAM, CONTEXT_ID_PARAM, CONTEXT_INITIALIZER_CLASSES_PARAM, GLOBAL_INITIALIZER_CLASSES_PARAM, LOCATOR_FACTORY_KEY_PARAM, LOCATOR_FACTORY_SELECTOR_PARAM

Constructor Summary

Constructors

Constructor and Description
JohnsonContextLoaderListener()
JohnsonContextLoaderListener(org.springframework.web.context.WebApplicationContext context)

Method Summary

Modifier and Type	Method and Description
void	contextDestroyed(javax.servlet.ServletContextEvent event) Performs standard Spring ContextLoaderListener teardown and ensures any attributes added to the servlet context for this dispatcher are removed.
protected Event	createEvent(String defaultEventType, String defaultMessage, Throwable t) May be overridden in derived classes to allow them to override the default event type or message based on application-specific understanding of the exception that was thrown.
org.springframework.web.context.WebApplicationContext	initWebApplicationContext(javax.servlet.ServletContext servletContext) Overrides the standard Spring ContextLoaderListener initialisation to make it Johnson-aware, allowing it to be automatically bypassed, when application checks produce fatal events, or add an Event if initialisation fails.

Methods inherited from class org.springframework.web.context.ContextLoaderListener

contextInitialized, createContextLoader, getContextLoader

Methods inherited from class org.springframework.web.context.ContextLoader

closeWebApplicationContext, configureAndRefreshWebApplicationContext, createWebApplicationContext, createWebApplicationContext, customizeContext, determineContextClass, determineContextInitializerClasses, getCurrentWebApplicationContext, loadParentContext

Methods inherited from class java.lang.Object

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

Field Detail

ATTR_BYPASSED

public static final String ATTR_BYPASSED

The attribute added to the ServletContext when Spring context initialization is bypassed because a previous Event indicates the application has already failed.

Since:

3.0

Constructor Detail

JohnsonContextLoaderListener

public JohnsonContextLoaderListener()

JohnsonContextLoaderListener

public JohnsonContextLoaderListener(org.springframework.web.context.WebApplicationContext context)

Method Detail

contextDestroyed

public void contextDestroyed(javax.servlet.ServletContextEvent event)

Performs standard Spring ContextLoaderListener teardown and ensures any attributes added to the servlet context for this dispatcher are removed.

Specified by:

contextDestroyed in interface javax.servlet.ServletContextListener

Overrides:

contextDestroyed in class org.springframework.web.context.ContextLoaderListener

Parameters:

event - the context event

initWebApplicationContext

public org.springframework.web.context.WebApplicationContext initWebApplicationContext(javax.servlet.ServletContext servletContext)

Overrides the standard Spring ContextLoaderListener initialisation to make it Johnson-aware, allowing it to be automatically bypassed, when application checks produce fatal events, or add an Event if initialisation fails.

This implementation will never throw an exception. Unlike the base implementation, though, it may return null if initialisation is bypassed (due to previous fatal events or failing to initialise) or if initialisation fails.

Overrides:

initWebApplicationContext in class org.springframework.web.context.ContextLoader

Parameters:

servletContext - the servlet context

Returns:

the initialised context, or null if initialisation is bypassed or fails

createEvent

@Nonnull
protected Event createEvent(@Nonnull
                                     String defaultEventType,
                                     @Nonnull
                                     String defaultMessage,
                                     @Nonnull
                                     Throwable t)

May be overridden in derived classes to allow them to override the default event type or message based on application-specific understanding of the exception that was thrown.

For cases where derived classes are not able to offer a more specific event type or message, they are encouraged to fall back on the behaviour of this superclass method.

Parameters:

defaultEventType - the default event type to use if no more specific type is appropriate

defaultMessage - the default message to use if no more specific message is available

t - the exception thrown while attempting to initialise the WebApplicationContext

Returns:

the event to add to Johnson, which may not be null