M1 cut of environment, profiles and property work (SPR-7508)

Decomposed Environment interface into PropertySources, PropertyResolver
objects

    Environment interface and implementations are still present, but
    simpler.

    PropertySources container aggregates PropertySource objects;
    PropertyResolver provides search, conversion, placeholder
    replacement. Single implementation for now is
    PropertySourcesPlaceholderResolver

Renamed EnvironmentAwarePropertyPlaceholderConfigurer to
PropertySourcesPlaceholderConfigurer

    <context:property-placeholder/> now registers PSPC by default, else
    PPC if systemPropertiesMode* settings are involved

Refined configuration and behavior of default profiles

    See Environment interface Javadoc for details

Added Portlet implementations of relevant interfaces:

    * DefaultPortletEnvironment
    * PortletConfigPropertySource, PortletContextPropertySource
    * Integrated each appropriately throughout Portlet app contexts

Added protected 'createEnvironment()' method to AbstractApplicationContext

    Subclasses can override at will to supply a custom Environment
    implementation.  In practice throughout the framework, this is how
    Web- and Portlet-related ApplicationContexts override use of the
    DefaultEnvironment and swap in DefaultWebEnvironment or
    DefaultPortletEnvironment as appropriate.

Introduced "stub-and-replace" behavior for Servlet- and Portlet-based
PropertySource implementations

    Allows for early registration and ordering of the stub, then
    replacement with actual backing object at refresh() time.

    Added AbstractApplicationContext.initPropertySources() method to
    support stub-and-replace behavior. Called from within existing
    prepareRefresh() method so as to avoid impact with
    ApplicationContext implementations that copy and modify AAC's
    refresh() method (e.g.: Spring DM).

    Added methods to WebApplicationContextUtils and
    PortletApplicationContextUtils to support stub-and-replace behavior

Added comprehensive Javadoc for all new or modified types and members

Added XSD documentation for all new or modified elements and attributes

    Including nested <beans>, <beans profile="..."/>, and changes for
    certain attributes type from xsd:IDREF to xsd:string

Improved fix for detecting non-file based Resources in
PropertiesLoaderSupport (SPR-7547, SPR-7552)

    Technically unrelated to environment work, but grouped in with
    this changeset for convenience.

Deprecated (removed) context:property-placeholder
'system-properties-mode' attribute from spring-context-3.1.xsd

    Functionality is preserved for those using schemas up to and including
    spring-context-3.0.  For 3.1, system-properties-mode is no longer
    supported as it conflicts with the idea of managing a set of property
    sources within the context's Environment object. See Javadoc in
    PropertyPlaceholderConfigurer, AbstractPropertyPlaceholderConfigurer
    and PropertySourcesPlaceholderConfigurer for details.

Introduced CollectionUtils.toArray(Enumeration<E>, A[])

Work items remaining for 3.1 M2:

    Consider repackaging PropertySource* types; eliminate internal use
    of SystemPropertyUtils and deprecate

    Further work on composition of Environment interface; consider
    repurposing existing PlaceholderResolver interface to obviate need
    for resolve[Required]Placeholder() methods currently in Environment.

    Ensure configurability of placeholder prefix, suffix, and value
    separator when working against an AbstractPropertyResolver

    Add JNDI-based Environment / PropertySource implementatinos

    Consider support for @Profile at the @Bean level

    Provide consistent logging for the entire property resolution
    lifecycle; consider issuing all such messages against a dedicated
    logger with a single category.

    Add reference documentation to cover the featureset.

org.springframework.web/src/test/java/org/springframework/web/context/support/DefaultWebEnvironmentTests.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2002-2010 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.support;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.util.List;
+
+import org.junit.Test;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.DefaultEnvironment;
+import org.springframework.core.env.PropertySource;
+
+
+public class DefaultWebEnvironmentTests {
+
+	@Test
+	public void propertySourceOrder() {
+		ConfigurableEnvironment env = new DefaultWebEnvironment();
+		List<PropertySource<?>> sources = env.getPropertySources().asList();
+		assertThat(sources.size(), is(4));
+		assertThat(sources.get(0).getName(), equalTo(DefaultWebEnvironment.SERVLET_CONFIG_PROPERTY_SOURCE_NAME));
+		assertThat(sources.get(1).getName(), equalTo(DefaultWebEnvironment.SERVLET_CONTEXT_PROPERTY_SOURCE_NAME));
+		assertThat(sources.get(2).getName(), equalTo(DefaultEnvironment.SYSTEM_PROPERTIES_PROPERTY_SOURCE_NAME));
+		assertThat(sources.get(3).getName(), equalTo(DefaultEnvironment.SYSTEM_ENVIRONMENT_PROPERTY_SOURCE_NAME));
+	}
+}