Introduce ConfigurableWebEnvironment

Changes introduced in Spring 3.1 for Environment support inadvertently
established a cyclic dependency between the
org.springframework.web.context and
org.springframework.web.context.support packages, specifically through
web.context.ContextLoader's invocation of
web.context.support.WebApplicationContextUtils#initServletPropertySources.

This commit introduces ConfigurableWebEnvironment to break this cyclic
dependency. All web.context.ConfigurableWebApplicationContext types now
return web.context.ConfigurableWebEnvironment from their #getEnvironment
methods; web.context.support.StandardServletEnvironment now implements
ConfigurableWebEnvironment and makes the call to
web.context.support.WebApplicationContextUtils#initServletPropertySources
within its implementation of #initPropertySources. This means that
web.context.ContextLoader now invokes
web.context.ConfigurableWebEnvironment#initPropertySources instead of
web.context.support.WebApplicationContextUtils#initServletPropertySources
and thus the cycle is broken.

Issue: SPR-9439

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -71,6 +71,11 @@ public interface ConfigurableWebApplicationContext extends WebApplicationContext
 	 */
 	ServletConfig getServletConfig();
 
+	/**
+	 * Return the {@link ConfigurableWebEnvironment} used by this web application context.
+	 */
+	ConfigurableWebEnvironment getEnvironment();
+
 	/**
 	 * Set the namespace for this web application context,
 	 * to be used for building a default context config location.

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

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2002-2012 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.context;
+
+import javax.servlet.ServletConfig;
+import javax.servlet.ServletContext;
+
+import org.springframework.core.env.ConfigurableEnvironment;
+
+/**
+ * Specialization of {@link ConfigurableEnvironment} allowing initialization of
+ * servlet-related {@link org.springframework.core.env.PropertySource} objects at the
+ * earliest moment the {@link ServletContext} and (optionally) {@link ServletConfig}
+ * become available.
+ *
+ * @author Chris Beams
+ * @since 3.1.2
+ * @see ConfigurableWebApplicationContext#getEnvironment()
+ */
+public interface ConfigurableWebEnvironment extends ConfigurableEnvironment {
+
+	/**
+	 * Replace any {@linkplain
+	 * org.springframework.core.env.PropertySource.StubPropertySource stub property source}
+	 * instances acting as placeholders with real servlet context/config property sources
+	 * using the given parameters.
+	 * @param servletContext the {@link ServletContext} (may not be {@code null})
+	 * @param servletConfig the {@link ServletContext} ({@code null} if not available)
+	 */
+	void initPropertySources(ServletContext servletContext, ServletConfig servletConfig);
+
+}

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

@@ -44,7 +44,6 @@ import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
-import org.springframework.web.context.support.WebApplicationContextUtils;
 
 /**
  * Performs the actual initialization work for the root application context.
@@ -485,15 +484,9 @@ public class ContextLoader {
 			initializerInstances.add(BeanUtils.instantiateClass(initializerClass));
 		}
 
+		applicationContext.getEnvironment().initPropertySources(servletContext, null);
+
 		Collections.sort(initializerInstances, new AnnotationAwareOrderComparator());
-
-		// eagerly attempt to initialize servlet property sources in case initializers
-		// below depend on accessing context-params via the Environment API. Note that
-		// depending on application context implementation, this initialization will be
-		// attempted again during context refresh.
-		WebApplicationContextUtils.initServletPropertySources(
-				applicationContext.getEnvironment().getPropertySources(), servletContext);
-
 		for (ApplicationContextInitializer<ConfigurableApplicationContext> initializer : initializerInstances) {
 			initializer.initialize(applicationContext);
 		}

spring-web/src/main/java/org/springframework/web/context/support/AbstractRefreshableWebApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -27,7 +27,9 @@ import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
+import org.springframework.web.context.ConfigurableWebEnvironment;
 import org.springframework.web.context.ServletConfigAware;
 import org.springframework.web.context.ServletContextAware;
 
@@ -139,6 +141,14 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 		return new StandardServletEnvironment();
 	}
 
+	@Override
+	public ConfigurableWebEnvironment getEnvironment() {
+		ConfigurableEnvironment env = super.getEnvironment();
+		Assert.isInstanceOf(ConfigurableWebEnvironment.class, env,
+				"ConfigurableWebApplicationContext environment must be of type " +
+				"ConfigurableWebEnvironment");
+		return (ConfigurableWebEnvironment) env;
+	}
 
 	/**
 	 * Register request/session scopes, a {@link ServletContextAwareProcessor}, etc.
@@ -186,9 +196,7 @@ public abstract class AbstractRefreshableWebApplicationContext extends AbstractR
 	@Override
 	protected void initPropertySources() {
 		super.initPropertySources();
-		WebApplicationContextUtils.initServletPropertySources(
-				this.getEnvironment().getPropertySources(), this.servletContext,
-				this.servletConfig);
+		this.getEnvironment().initPropertySources(this.servletContext, this.servletConfig);
 	}
 
 	public Theme getTheme(String themeName) {

spring-web/src/main/java/org/springframework/web/context/support/GenericWebApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -28,9 +28,11 @@ import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
+import org.springframework.web.context.ConfigurableWebEnvironment;
 import org.springframework.web.context.ServletContextAware;
 
 /**
@@ -130,6 +132,15 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 		return new StandardServletEnvironment();
 	}
 
+	@Override
+	public ConfigurableWebEnvironment getEnvironment() {
+		ConfigurableEnvironment env = super.getEnvironment();
+		Assert.isInstanceOf(ConfigurableWebEnvironment.class, env,
+				"ConfigurableWebApplicationContext environment must be of type " +
+				"ConfigurableWebEnvironment");
+		return (ConfigurableWebEnvironment) env;
+	}
+
 	/**
 	 * Register ServletContextAwareProcessor.
 	 * @see ServletContextAwareProcessor
@@ -176,8 +187,7 @@ public class GenericWebApplicationContext extends GenericApplicationContext
 	@Override
 	protected void initPropertySources() {
 		super.initPropertySources();
-		WebApplicationContextUtils.initServletPropertySources(
-				this.getEnvironment().getPropertySources(), this.servletContext);
+		this.getEnvironment().initPropertySources(this.servletContext, null);
 	}
 
 	public Theme getTheme(String themeName) {

spring-web/src/main/java/org/springframework/web/context/support/StandardServletEnvironment.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -26,6 +26,7 @@ import org.springframework.core.env.PropertySource.StubPropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.jndi.JndiLocatorDelegate;
 import org.springframework.jndi.JndiPropertySource;
+import org.springframework.web.context.ConfigurableWebEnvironment;
 
 /**
  * {@link Environment} implementation to be used by {@code Servlet}-based web
@@ -40,7 +41,8 @@ import org.springframework.jndi.JndiPropertySource;
  * @since 3.1
  * @see StandardEnvironment
  */
-public class StandardServletEnvironment extends StandardEnvironment {
+public class StandardServletEnvironment extends StandardEnvironment
+		implements ConfigurableWebEnvironment {
 
 	/** Servlet context init parameters property source name: {@value} */
 	public static final String SERVLET_CONTEXT_PROPERTY_SOURCE_NAME = "servletContextInitParams";
@@ -68,15 +70,15 @@ public class StandardServletEnvironment extends StandardEnvironment {
 	 * environment variables contributed by the {@link StandardEnvironment} superclass.
 	 * <p>The {@code Servlet}-related property sources are added as {@link
 	 * StubPropertySource stubs} at this stage, and will be {@linkplain
-	 * WebApplicationContextUtils#initServletPropertySources fully initialized} once the
-	 * actual {@link ServletConfig} and {@link ServletContext} objects become available.
+	 * #initPropertySources(ServletContext) fully initialized} once the actual
+	 * {@link ServletContext} object becomes available.
 	 * @see StandardEnvironment#customizePropertySources
 	 * @see org.springframework.core.env.AbstractEnvironment#customizePropertySources
 	 * @see ServletConfigPropertySource
 	 * @see ServletContextPropertySource
 	 * @see org.springframework.jndi.JndiPropertySource
 	 * @see org.springframework.context.support.AbstractApplicationContext#initPropertySources
-	 * @see WebApplicationContextUtils#initServletPropertySources
+	 * @see #initPropertySources(ServletContext)
 	 */
 	@Override
 	protected void customizePropertySources(MutablePropertySources propertySources) {
@@ -88,4 +90,9 @@ public class StandardServletEnvironment extends StandardEnvironment {
 		super.customizePropertySources(propertySources);
 	}
 
+	public void initPropertySources(ServletContext servletContext, ServletConfig servletConfig) {
+		WebApplicationContextUtils.initServletPropertySources(
+				this.getPropertySources(), servletContext, servletConfig);
+	}
+
 }

spring-web/src/main/java/org/springframework/web/context/support/StaticWebApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -27,7 +27,9 @@ import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.ui.context.Theme;
 import org.springframework.ui.context.ThemeSource;
 import org.springframework.ui.context.support.UiApplicationContextUtils;
+import org.springframework.util.Assert;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
+import org.springframework.web.context.ConfigurableWebEnvironment;
 import org.springframework.web.context.ServletConfigAware;
 import org.springframework.web.context.ServletContextAware;
 
@@ -167,6 +169,15 @@ public class StaticWebApplicationContext extends StaticApplicationContext
 		return new StandardServletEnvironment();
 	}
 
+	@Override
+	public ConfigurableWebEnvironment getEnvironment() {
+		ConfigurableEnvironment env = super.getEnvironment();
+		Assert.isInstanceOf(ConfigurableWebEnvironment.class, env,
+				"ConfigurableWebApplication environment must be of type " +
+				"ConfigurableWebEnvironment");
+		return (ConfigurableWebEnvironment) env;
+	}
+
 	/**
 	 * Initialize the theme capability.
 	 */