001/*
002 * Copyright 2002-2016 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.context;
018
019import javax.servlet.ServletContext;
020
021import org.springframework.context.ApplicationContext;
022import org.springframework.lang.Nullable;
023
024/**
025 * Interface to provide configuration for a web application. This is read-only while
026 * the application is running, but may be reloaded if the implementation supports this.
027 *
028 * <p>This interface adds a {@code getServletContext()} method to the generic
029 * ApplicationContext interface, and defines a well-known application attribute name
030 * that the root context must be bound to in the bootstrap process.
031 *
032 * <p>Like generic application contexts, web application contexts are hierarchical.
033 * There is a single root context per application, while each servlet in the application
034 * (including a dispatcher servlet in the MVC framework) has its own child context.
035 *
036 * <p>In addition to standard application context lifecycle capabilities,
037 * WebApplicationContext implementations need to detect {@link ServletContextAware}
038 * beans and invoke the {@code setServletContext} method accordingly.
039 *
040 * @author Rod Johnson
041 * @author Juergen Hoeller
042 * @since January 19, 2001
043 * @see ServletContextAware#setServletContext
044 */
045public interface WebApplicationContext extends ApplicationContext {
046
047        /**
048         * Context attribute to bind root WebApplicationContext to on successful startup.
049         * <p>Note: If the startup of the root context fails, this attribute can contain
050         * an exception or error as value. Use WebApplicationContextUtils for convenient
051         * lookup of the root WebApplicationContext.
052         * @see org.springframework.web.context.support.WebApplicationContextUtils#getWebApplicationContext
053         * @see org.springframework.web.context.support.WebApplicationContextUtils#getRequiredWebApplicationContext
054         */
055        String ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE = WebApplicationContext.class.getName() + ".ROOT";
056
057        /**
058         * Scope identifier for request scope: "request".
059         * Supported in addition to the standard scopes "singleton" and "prototype".
060         */
061        String SCOPE_REQUEST = "request";
062
063        /**
064         * Scope identifier for session scope: "session".
065         * Supported in addition to the standard scopes "singleton" and "prototype".
066         */
067        String SCOPE_SESSION = "session";
068
069        /**
070         * Scope identifier for the global web application scope: "application".
071         * Supported in addition to the standard scopes "singleton" and "prototype".
072         */
073        String SCOPE_APPLICATION = "application";
074
075        /**
076         * Name of the ServletContext environment bean in the factory.
077         * @see javax.servlet.ServletContext
078         */
079        String SERVLET_CONTEXT_BEAN_NAME = "servletContext";
080
081        /**
082         * Name of the ServletContext init-params environment bean in the factory.
083         * <p>Note: Possibly merged with ServletConfig parameters.
084         * ServletConfig parameters override ServletContext parameters of the same name.
085         * @see javax.servlet.ServletContext#getInitParameterNames()
086         * @see javax.servlet.ServletContext#getInitParameter(String)
087         * @see javax.servlet.ServletConfig#getInitParameterNames()
088         * @see javax.servlet.ServletConfig#getInitParameter(String)
089         */
090        String CONTEXT_PARAMETERS_BEAN_NAME = "contextParameters";
091
092        /**
093         * Name of the ServletContext attributes environment bean in the factory.
094         * @see javax.servlet.ServletContext#getAttributeNames()
095         * @see javax.servlet.ServletContext#getAttribute(String)
096         */
097        String CONTEXT_ATTRIBUTES_BEAN_NAME = "contextAttributes";
098
099
100        /**
101         * Return the standard Servlet API ServletContext for this application.
102         */
103        @Nullable
104        ServletContext getServletContext();
105
106}