Initialize application context with initializer-given ServletContext

Closes gh-22319

Author: jhoeller

spring-web/src/main/java/org/springframework/web/context/AbstractContextLoaderInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -58,7 +58,7 @@ public void onStartup(ServletContext servletContext) throws ServletException {
 	protected void registerContextLoaderListener(ServletContext servletContext) {
 		WebApplicationContext rootAppContext = createRootApplicationContext();
 		if (rootAppContext != null) {
-			ContextLoaderListener listener = new ContextLoaderListener(rootAppContext);
+			ContextLoaderListener listener = new ContextLoaderListener(rootAppContext, servletContext);
 			listener.setContextInitializers(getRootApplicationContextInitializers());
 			servletContext.addListener(listener);
 		}

spring-web/src/main/java/org/springframework/web/context/ContextLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -152,7 +152,7 @@ public class ContextLoader {
 	 * The root WebApplicationContext instance that this loader manages.
 	 */
 	@Nullable
-	private WebApplicationContext context;
+	private WebApplicationContext rootContext;
 
 	/** Actual ApplicationContextInitializer instances to apply to the context. */
 	private final List<ApplicationContextInitializer<ConfigurableApplicationContext>> contextInitializers =
@@ -205,12 +205,12 @@ public ContextLoader() {
 	 * WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE} and subclasses are
 	 * free to call the {@link #closeWebApplicationContext} method on container shutdown
 	 * to close the application context.
-	 * @param context the application context to manage
+	 * @param rootContext the application context to manage
 	 * @see #initWebApplicationContext(ServletContext)
 	 * @see #closeWebApplicationContext(ServletContext)
 	 */
-	public ContextLoader(WebApplicationContext context) {
-		this.context = context;
+	public ContextLoader(WebApplicationContext rootContext) {
+		this.rootContext = rootContext;
 	}
 
 
@@ -259,10 +259,10 @@ public WebApplicationContext initWebApplicationContext(ServletContext servletCon
 		try {
 			// Store context in local instance variable, to guarantee that
 			// it is available on ServletContext shutdown.
-			if (this.context == null) {
-				this.context = createWebApplicationContext(servletContext);
+			if (this.rootContext == null) {
+				this.rootContext = createWebApplicationContext(servletContext);
 			}
-			if (this.context instanceof ConfigurableWebApplicationContext cwac && !cwac.isActive()) {
+			if (this.rootContext instanceof ConfigurableWebApplicationContext cwac && !cwac.isActive()) {
 				// The context has not yet been refreshed -> provide services such as
 				// setting the parent context, setting the application context id, etc
 				if (cwac.getParent() == null) {
@@ -273,22 +273,22 @@ public WebApplicationContext initWebApplicationContext(ServletContext servletCon
 				}
 				configureAndRefreshWebApplicationContext(cwac, servletContext);
 			}
-			servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);
+			servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.rootContext);
 
 			ClassLoader ccl = Thread.currentThread().getContextClassLoader();
 			if (ccl == ContextLoader.class.getClassLoader()) {
-				currentContext = this.context;
+				currentContext = this.rootContext;
 			}
 			else if (ccl != null) {
-				currentContextPerThread.put(ccl, this.context);
+				currentContextPerThread.put(ccl, this.rootContext);
 			}
 
 			if (logger.isInfoEnabled()) {
 				long elapsedTime = System.currentTimeMillis() - startTime;
 				logger.info("Root WebApplicationContext initialized in " + elapsedTime + " ms");
 			}
 
-			return this.context;
+			return this.rootContext;
 		}
 		catch (RuntimeException | Error ex) {
 			logger.error("Context initialization failed", ex);
@@ -506,7 +506,7 @@ protected ApplicationContext loadParentContext(ServletContext servletContext) {
 	public void closeWebApplicationContext(ServletContext servletContext) {
 		servletContext.log("Closing Spring root WebApplicationContext");
 		try {
-			if (this.context instanceof ConfigurableWebApplicationContext cwac) {
+			if (this.rootContext instanceof ConfigurableWebApplicationContext cwac) {
 				cwac.close();
 			}
 		}

spring-web/src/main/java/org/springframework/web/context/ContextLoaderListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,9 +16,12 @@
 
 package org.springframework.web.context;
 
+import jakarta.servlet.ServletContext;
 import jakarta.servlet.ServletContextEvent;
 import jakarta.servlet.ServletContextListener;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Bootstrap listener to start up and shut down Spring's root {@link WebApplicationContext}.
  * Simply delegates to {@link ContextLoader} as well as to {@link ContextCleanupListener}.
@@ -36,6 +39,10 @@
  */
 public class ContextLoaderListener extends ContextLoader implements ServletContextListener {
 
+	@Nullable
+	private ServletContext servletContext;
+
+
 	/**
 	 * Create a new {@code ContextLoaderListener} that will create a web application
 	 * context based on the "contextClass" and "contextConfigLocation" servlet
@@ -56,6 +63,19 @@ public class ContextLoaderListener extends ContextLoader implements ServletConte
 	public ContextLoaderListener() {
 	}
 
+	/**
+	 * Create a new {@code ContextLoaderListener} with the given application context,
+	 * initializing it with the {@link ServletContextEvent}-provided
+	 * {@link ServletContext} reference which is spec-restricted in terms of capabilities.
+	 * <p>It is generally preferable to initialize the application context with a
+	 * {@link org.springframework.web.WebApplicationInitializer#onStartup}-given reference
+	 * which is usually fully capable.
+	 * @see #ContextLoaderListener(WebApplicationContext, ServletContext)
+	 */
+	public ContextLoaderListener(WebApplicationContext rootContext) {
+		super(rootContext);
+	}
+
 	/**
 	 * Create a new {@code ContextLoaderListener} with the given application context. This
 	 * constructor is useful in Servlet initializers where instance-based registration of
@@ -85,12 +105,15 @@ public ContextLoaderListener() {
 	 * WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE} and the Spring
 	 * application context will be closed when the {@link #contextDestroyed} lifecycle
 	 * method is invoked on this listener.
-	 * @param context the application context to manage
+	 * @param rootContext the application context to manage
+	 * @param servletContext the ServletContext to initialize with
+	 * @since 6.2
 	 * @see #contextInitialized(ServletContextEvent)
 	 * @see #contextDestroyed(ServletContextEvent)
 	 */
-	public ContextLoaderListener(WebApplicationContext context) {
-		super(context);
+	public ContextLoaderListener(WebApplicationContext rootContext, ServletContext servletContext) {
+		super(rootContext);
+		this.servletContext = servletContext;
 	}
 
 
@@ -99,7 +122,8 @@ public ContextLoaderListener(WebApplicationContext context) {
 	 */
 	@Override
 	public void contextInitialized(ServletContextEvent event) {
-		initWebApplicationContext(event.getServletContext());
+		ServletContext scToUse = getServletContextToUse(event);
+		initWebApplicationContext(scToUse);
 	}
 
 
@@ -108,8 +132,17 @@ public void contextInitialized(ServletContextEvent event) {
 	 */
 	@Override
 	public void contextDestroyed(ServletContextEvent event) {
-		closeWebApplicationContext(event.getServletContext());
-		ContextCleanupListener.cleanupAttributes(event.getServletContext());
+		ServletContext scToUse = getServletContextToUse(event);
+		closeWebApplicationContext(scToUse);
+		ContextCleanupListener.cleanupAttributes(scToUse);
+	}
+
+	/**
+	 * Preferably use a fully-capable local ServletContext instead of
+	 * the spec-restricted ServletContextEvent-provided reference.
+	 */
+	private ServletContext getServletContextToUse(ServletContextEvent event) {
+		return (this.servletContext != null ? this.servletContext : event.getServletContext());
 	}
 
 }