001/* 002 * Copyright 2002-2017 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.support; 018 019import java.util.Map; 020import javax.servlet.ServletContext; 021 022import org.apache.commons.logging.Log; 023import org.apache.commons.logging.LogFactory; 024 025import org.springframework.web.context.ServletContextAware; 026 027/** 028 * Exporter that takes Spring-defined objects and exposes them as 029 * ServletContext attributes. Usually, bean references will be used 030 * to export Spring-defined beans as ServletContext attributes. 031 * 032 * <p>Useful to make Spring-defined beans available to code that is 033 * not aware of Spring at all, but rather just of the Servlet API. 034 * Client code can then use plain ServletContext attribute lookups 035 * to access those objects, despite them being defined in a Spring 036 * application context. 037 * 038 * <p>Alternatively, consider using the WebApplicationContextUtils 039 * class to access Spring-defined beans via the WebApplicationContext 040 * interface. This makes client code aware of Spring API, of course. 041 * 042 * @author Juergen Hoeller 043 * @since 1.1.4 044 * @see javax.servlet.ServletContext#getAttribute 045 * @see WebApplicationContextUtils#getWebApplicationContext 046 */ 047public class ServletContextAttributeExporter implements ServletContextAware { 048 049 protected final Log logger = LogFactory.getLog(getClass()); 050 051 private Map<String, Object> attributes; 052 053 054 /** 055 * Set the ServletContext attributes to expose as key-value pairs. 056 * Each key will be considered a ServletContext attributes key, 057 * and each value will be used as corresponding attribute value. 058 * <p>Usually, you will use bean references for the values, 059 * to export Spring-defined beans as ServletContext attributes. 060 * Of course, it is also possible to define plain values to export. 061 */ 062 public void setAttributes(Map<String, Object> attributes) { 063 this.attributes = attributes; 064 } 065 066 @Override 067 public void setServletContext(ServletContext servletContext) { 068 if (this.attributes != null) { 069 for (Map.Entry<String, Object> entry : this.attributes.entrySet()) { 070 String attributeName = entry.getKey(); 071 if (logger.isWarnEnabled()) { 072 if (servletContext.getAttribute(attributeName) != null) { 073 logger.warn("Replacing existing ServletContext attribute with name '" + attributeName + "'"); 074 } 075 } 076 servletContext.setAttribute(attributeName, entry.getValue()); 077 if (logger.isInfoEnabled()) { 078 logger.info("Exported ServletContext attribute with name '" + attributeName + "'"); 079 } 080 } 081 } 082 } 083 084}