public class

ContextLoaderPlugIn

extends Object
java.lang.Object
   ↳ org.springframework.web.struts.ContextLoaderPlugIn

This class is deprecated.
as of Spring 3.0

Class Overview

Struts 1.1+ PlugIn that loads a Spring application context for the Struts ActionServlet. This context will automatically refer to the root WebApplicationContext (loaded by ContextLoaderListener/Servlet) as parent.

The default namespace of the WebApplicationContext is the name of the Struts ActionServlet, suffixed with "-servlet" (e.g. "action-servlet"). The default location of the XmlWebApplicationContext configuration file is therefore "/WEB-INF/action-servlet.xml". 

 <plug-in className="org.springframework.web.struts.ContextLoaderPlugIn"/>
The location of the context configuration files can be customized through the "contextConfigLocation" setting, analogous to the root WebApplicationContext and FrameworkServlet contexts. 
 <plug-in className="org.springframework.web.struts.ContextLoaderPlugIn">
   <set-property property="contextConfigLocation" value="/WEB-INF/action-servlet.xml /WEB-INF/myContext.xml"/>
 </plug-in>
Beans defined in the ContextLoaderPlugIn context can be accessed from conventional Struts Actions, via fetching the WebApplicationContext reference from the ServletContext. ActionSupport and DispatchActionSupport are pre-built convenience classes that provide easy access to the context.

It is normally preferable to access Spring's root WebApplicationContext in such scenarios, though: A shared middle tier should be defined there rather than in a ContextLoaderPlugin context, for access by any web component. ActionSupport and DispatchActionSupport autodetect the root context too.

A special usage of this PlugIn is to define Struts Actions themselves as beans, typically wiring them with middle tier components defined in the root context. Such Actions will then be delegated to by proxy definitions in the Struts configuration, using the DelegatingActionProxy class or the DelegatingRequestProcessor.

Note that you can use a single ContextLoaderPlugIn for all Struts modules. That context can in turn be loaded from multiple XML files, for example split according to Struts modules. Alternatively, define one ContextLoaderPlugIn per Struts module, specifying appropriate "contextConfigLocation" parameters.

Note: The idea of delegating to Spring-managed Struts Actions originated in Don Brown's Spring Struts Plugin. ContextLoaderPlugIn and DelegatingActionProxy constitute a clean-room implementation of the same idea, essentially superseding the original plugin. Many thanks to Don Brown and Matt Raible for the original work and for the agreement to reimplement the idea in Spring proper!

See Also

Summary

Constants
String DEFAULT_NAMESPACE_SUFFIX Suffix for WebApplicationContext namespaces.
Fields
public static final Class DEFAULT_CONTEXT_CLASS Default context class for ContextLoaderPlugIn.
public static final String SERVLET_CONTEXT_PREFIX Prefix for the ServletContext attribute for the WebApplicationContext.
protected final Log logger
Public Constructors
ContextLoaderPlugIn()
Public Methods
void destroy()
Close the WebApplicationContext of the ActionServlet.
final ActionServlet getActionServlet()
Return the Struts ActionServlet that this PlugIn is associated with.
Class getContextClass()
Return the custom context class.
String getContextConfigLocation()
Return the explicit context config location, if any.
final ModuleConfig getModuleConfig()
Return the Struts ModuleConfig that this PlugIn is associated with.
final String getModulePrefix()
Return the prefix of the ModuleConfig that this PlugIn is associated with.
String getNamespace()
Return the namespace for the ActionServlet, falling back to default scheme if no custom namespace was set: e.g.
final ServletContext getServletContext()
Return the ServletContext that this PlugIn is associated with.
String getServletContextAttributeName()
Return the ServletContext attribute name for this PlugIn's WebApplicationContext.
final String getServletName()
Return the name of the ActionServlet that this PlugIn is associated with.
final WebApplicationContext getWebApplicationContext()
Return this PlugIn's WebApplicationContext.
final void init(ActionServlet actionServlet, ModuleConfig moduleConfig)
Create the ActionServlet's WebApplicationContext.
void setContextClass(Class contextClass)
Set a custom context class.
void setContextClassName(String contextClassName)
Set a custom context class by name.
void setContextConfigLocation(String contextConfigLocation)
Set the context config location explicitly, instead of relying on the default location built from the namespace.
void setNamespace(String namespace)
Set a custom namespace for the ActionServlet, to be used for building a default context config location.
Protected Methods
WebApplicationContext createWebApplicationContext(WebApplicationContext parent)
Instantiate the WebApplicationContext for the ActionServlet, either a default XmlWebApplicationContext or a custom context class if set.
WebApplicationContext initWebApplicationContext()
Initialize and publish the WebApplicationContext for the ActionServlet.
void onInit()
Callback for custom initialization after the context has been set up.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final String DEFAULT_NAMESPACE_SUFFIX

Suffix for WebApplicationContext namespaces. If a Struts ActionServlet is given the name "action" in a context, the namespace used by this PlugIn will resolve to "action-servlet".

Constant Value: "-servlet"

Fields

public static final Class DEFAULT_CONTEXT_CLASS

Default context class for ContextLoaderPlugIn.

See Also

public static final String SERVLET_CONTEXT_PREFIX

Prefix for the ServletContext attribute for the WebApplicationContext. The completion is the Struts module name.

protected final Log logger

Public Constructors

public ContextLoaderPlugIn ()

Public Methods

public void destroy ()

Close the WebApplicationContext of the ActionServlet.

See Also

public final ActionServlet getActionServlet ()

Return the Struts ActionServlet that this PlugIn is associated with.

public Class getContextClass ()

Return the custom context class.

public String getContextConfigLocation ()

Return the explicit context config location, if any.

public final ModuleConfig getModuleConfig ()

Return the Struts ModuleConfig that this PlugIn is associated with.

public final String getModulePrefix ()

Return the prefix of the ModuleConfig that this PlugIn is associated with.

See Also
  • org.apache.struts.config.ModuleConfig#getPrefix

public String getNamespace ()

Return the namespace for the ActionServlet, falling back to default scheme if no custom namespace was set: e.g. "test-servlet" for a servlet named "test".

public final ServletContext getServletContext ()

Return the ServletContext that this PlugIn is associated with.

public String getServletContextAttributeName ()

Return the ServletContext attribute name for this PlugIn's WebApplicationContext.

The default implementation returns SERVLET_CONTEXT_PREFIX + module prefix.

See Also

public final String getServletName ()

Return the name of the ActionServlet that this PlugIn is associated with.

public final WebApplicationContext getWebApplicationContext ()

Return this PlugIn's WebApplicationContext.

public final void init (ActionServlet actionServlet, ModuleConfig moduleConfig)

Create the ActionServlet's WebApplicationContext.

Throws
ServletException

public void setContextClass (Class contextClass)

Set a custom context class. This class must be of type WebApplicationContext, when using the default ContextLoaderPlugIn implementation, the context class must also implement ConfigurableWebApplicationContext.

See Also

public void setContextClassName (String contextClassName)

Set a custom context class by name. This class must be of type WebApplicationContext, when using the default ContextLoaderPlugIn implementation, the context class must also implement ConfigurableWebApplicationContext.

Throws
ClassNotFoundException
See Also

public void setContextConfigLocation (String contextConfigLocation)

Set the context config location explicitly, instead of relying on the default location built from the namespace. This location string can consist of multiple locations separated by any number of commas and spaces.

public void setNamespace (String namespace)

Set a custom namespace for the ActionServlet, to be used for building a default context config location.

Protected Methods

protected WebApplicationContext createWebApplicationContext (WebApplicationContext parent)

Instantiate the WebApplicationContext for the ActionServlet, either a default XmlWebApplicationContext or a custom context class if set.

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

Throws
BeansException if the context couldn't be initialized
See Also

protected WebApplicationContext initWebApplicationContext ()

Initialize and publish the WebApplicationContext for the ActionServlet.

Delegates to createWebApplicationContext(WebApplicationContext) for actual creation.

Can be overridden in subclasses. Call getActionServlet() and/or getModuleConfig() to access the Struts configuration that this PlugIn is associated with.

Throws
BeansException if the context couldn't be initialized
IllegalStateException if there is already a context for the Struts ActionServlet
See Also

protected void onInit ()

Callback for custom initialization after the context has been set up.

Throws
ServletException if initialization failed