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.test/src/main/java/org/springframework/mock/env/MockPropertySource.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2002-2011 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.mock.env;
+
+import java.util.Properties;
+
+import org.springframework.core.env.PropertiesPropertySource;
+import org.springframework.core.env.PropertySource;
+
+/**
+ * Simple {@link PropertySource} implementation for use in testing. Accepts
+ * a user-provided {@link Properties} object, or if omitted during construction,
+ * the implementation will initialize its own.
+ *
+ * The {@link #setProperty} and {@link #withProperty} methods are exposed for
+ * convenience, for example:
+ * <pre>
+ * {@code
+ *   PropertySource<?> source = new MockPropertySource().withProperty("foo", "bar");
+ * }
+ * </pre>
+ *
+ * @author Chris Beams
+ * @since 3.1
+ * @see MockEnvironment
+ */
+public class MockPropertySource extends PropertiesPropertySource {
+
+	/**
+	 * {@value} is the default name for {@link MockPropertySource} instances not
+	 * otherwise given an explicit name.
+	 * @see #MockPropertySource()
+	 * @see #MockPropertySource(String)
+	 */
+	public static final String MOCK_PROPERTIES_PROPERTY_SOURCE_NAME = "mockProperties";
+
+	/**
+	 * Create a new {@code MockPropertySource} named {@value #MOCK_PROPERTIES_PROPERTY_SOURCE_NAME}
+	 * that will maintain its own internal {@link Properties} instance.
+	 */
+	public MockPropertySource() {
+		this(new Properties());
+	}
+
+	/**
+	 * Create a new {@code MockPropertySource} with the given name that will
+	 * maintain its own internal {@link Properties} instance.
+	 * @param name the {@linkplain #getName() name} of the property source
+	 */
+	public MockPropertySource(String name) {
+		this(name, new Properties());
+	}
+
+	/**
+	 * Create a new {@code MockPropertySource} named {@value #MOCK_PROPERTIES_PROPERTY_SOURCE_NAME}
+	 * and backed by the given {@link Properties} object.
+	 * @param properties the properties to use
+	 */
+	public MockPropertySource(Properties properties) {
+		this(MOCK_PROPERTIES_PROPERTY_SOURCE_NAME, properties);
+	}
+
+	/**
+	 * Create a new {@code MockPropertySource} with with the given name and backed by the given
+	 * {@link Properties} object
+	 * @param name the {@linkplain #getName() name} of the property source
+	 * @param properties the properties to use
+	 */
+	public MockPropertySource(String name, Properties properties) {
+		super(name, properties);
+	}
+
+	/**
+	 * Set the given property on the underlying {@link Properties} object.
+	 */
+	public void setProperty(String key, String value) {
+		this.source.put(key, value);
+	}
+
+	/**
+	 * Convenient synonym for {@link #setProperty} that returns the current instance.
+	 * Useful for method chaining and fluent-style use.
+	 * @return this {@link MockPropertySource} instance
+	 */
+	public MockPropertySource withProperty(String key, String value) {
+		this.setProperty(key, value);
+		return this;
+	}
+}