org.springframework.web.context
Class ContextLoader

java.lang.Object
  org.springframework.web.context.ContextLoader

public class ContextLoader

extends Object

Performs the actual initialization work for the root application context. Called by ContextLoaderListener and ContextLoaderServlet.

Regards a "contextClass" parameter at the web.xml context-param level, falling back to the default context class (XmlWebApplicationContext) if not found. With the default ContextLoader, a context class needs to implement ConfigurableWebApplicationContext.

Passes a "contextConfigLocation" context-param to the context instance, parsing it into potentially multiple file paths which can be separated by any number of commas and spaces, like "applicationContext1.xml, applicationContext2.xml". If not explicitly specified, the context implementation is supposed to use a default location (with XmlWebApplicationContext: "/WEB-INF/applicationContext.xml").

Note: In case of multiple config locations, later bean definitions will override ones defined in earlier loaded files, at least when using one of Spring's default ApplicationContext implementations. This can be leveraged to deliberately override certain bean definitions via an extra XML file.

Since:

17.02.2003

Author:

Juergen Hoeller, Colin Sampaleanu

See Also:

ContextLoaderListener, ContextLoaderServlet, ConfigurableWebApplicationContext, XmlWebApplicationContext

Field Summary

static String	CONFIG_LOCATION_PARAM Name of servlet context parameter that can specify the config location for the root context, falling back to the implementation's default else.
static String	CONTEXT_CLASS_PARAM Config param for the root WebApplicationContext implementation class to use: "contextClass"
static Class	DEFAULT_CONTEXT_CLASS Default context class for ContextLoader.

Constructor Summary

ContextLoader()

Method Summary

void	closeWebApplicationContext(ServletContext servletContext) Close Spring's web application context for the given servlet context.
protected WebApplicationContext	createWebApplicationContext(ServletContext servletContext, ApplicationContext parent) Instantiate the root WebApplicationContext for this loader, either a default XmlWebApplicationContext or a custom context class if specified.
WebApplicationContext	initWebApplicationContext(ServletContext servletContext) Initialize Spring's web application context for the given servlet context, regarding the "contextClass" and "contextConfigLocation" context-params.
protected ApplicationContext	loadParentContext(ServletContext servletContext) Template method which may be overridden by a subclass to load or obtain an ApplicationContext instance which will be used as the parent context of the root WebApplicationContext (if it is not null).

Methods inherited from class java.lang.Object

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

Field Detail

CONTEXT_CLASS_PARAM

public static final String CONTEXT_CLASS_PARAM

Config param for the root WebApplicationContext implementation class to use: "contextClass"

See Also:

Constant Field Values

DEFAULT_CONTEXT_CLASS

public static final Class DEFAULT_CONTEXT_CLASS

Default context class for ContextLoader.

See Also:

XmlWebApplicationContext

CONFIG_LOCATION_PARAM

public static final String CONFIG_LOCATION_PARAM

Name of servlet context parameter that can specify the config location for the root context, falling back to the implementation's default else.

See Also:

XmlWebApplicationContext.DEFAULT_CONFIG_LOCATION, Constant Field Values

Constructor Detail

ContextLoader

public ContextLoader()

Method Detail

initWebApplicationContext

public WebApplicationContext initWebApplicationContext(ServletContext servletContext)
                                                throws BeansException

Initialize Spring's web application context for the given servlet context, regarding the "contextClass" and "contextConfigLocation" context-params.

Parameters:

servletContext - current servlet context

Returns:

the new WebApplicationContext

Throws:

BeansException - if the context couldn't be initialized

See Also:

CONTEXT_CLASS_PARAM, CONFIG_LOCATION_PARAM

createWebApplicationContext

protected WebApplicationContext createWebApplicationContext(ServletContext servletContext,
                                                            ApplicationContext parent)
                                                     throws BeansException

Instantiate the root WebApplicationContext for this loader, either a default XmlWebApplicationContext or a custom context class if specified.

This implementation expects custom contexts to implement ConfigurableWebApplicationContext. Can be overridden in subclasses.

Parameters:

servletContext - current servlet context

parent - the parent ApplicationContext to use, or null if none

Throws:

BeansException - if the context couldn't be initialized

See Also:

CONTEXT_CLASS_PARAM, DEFAULT_CONTEXT_CLASS, ConfigurableWebApplicationContext, XmlWebApplicationContext

loadParentContext

protected ApplicationContext loadParentContext(ServletContext servletContext)
                                        throws BeansException

Template method which may be overridden by a subclass to load or obtain an ApplicationContext instance which will be used as the parent context of the root WebApplicationContext (if it is not null).

The main reason for this hook is to allow root web application contexts to be children of a shared EAR context that's also visible to EJBs. For pure web applications, there is usually no need to worry about this.

Parameters:

servletContext - current servlet context

Returns:

the parent application context, or null if none

Throws:

BeansException - if the context couldn't be initialized

closeWebApplicationContext

public void closeWebApplicationContext(ServletContext servletContext)
                                throws ApplicationContextException

Close Spring's web application context for the given servlet context.

Parameters:

servletContext - current servlet context

Throws:

ApplicationContextException