/*
* Copyright 2002-2008 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.filter;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceEditor;
import org.springframework.core.io.ResourceLoader;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.context.support.ServletContextResourceLoader;
import org.springframework.web.util.NestedServletException;
/**
* Simple base implementation of {@link javax.servlet.Filter} which treats
* its config parameters (<code>init-param</code> entries within the
* <code>filter</code> tag in <code>web.xml</code>) as bean properties.
*
* <p>A handy superclass for any type of filter. Type conversion of config
* parameters is automatic, with the corresponding setter method getting
* invoked with the converted value. It is also possible for subclasses to
* specify required properties. Parameters without matching bean property
* setter will simply be ignored.
*
* <p>This filter leaves actual filtering to subclasses, which have to
* implement the {@link javax.servlet.Filter#doFilter} method.
*
* <p>This generic filter base class has no dependency on the Spring
* {@link org.springframework.context.ApplicationContext} concept.
* Filters usually don't load their own context but rather access service
* beans from the Spring root application context, accessible via the
* filter's {@link #getServletContext() ServletContext} (see
* {@link org.springframework.web.context.support.WebApplicationContextUtils}).
*
* @author Juergen Hoeller
* @since 06.12.2003
* @see #addRequiredProperty
* @see #initFilterBean
* @see #doFilter
*/
public abstract class GenericFilterBean implements
Filter, BeanNameAware, ServletContextAware, InitializingBean, DisposableBean {
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
/**
* Set of required properties (Strings) that must be supplied as
* config parameters to this filter.
*/
private final Set requiredProperties = new HashSet();
/* The FilterConfig of this filter */
private FilterConfig filterConfig;
private String beanName;
private ServletContext servletContext;
/**
* Stores the bean name as defined in the Spring bean factory.
* <p>Only relevant in case of initialization as bean, to have a name as
* fallback to the filter name usually provided by a FilterConfig instance.
* @see org.springframework.beans.factory.BeanNameAware
* @see #getFilterName()
*/
public final void setBeanName(String beanName) {
this.beanName = beanName;
}
/**
* Stores the ServletContext that the bean factory runs in.
* <p>Only relevant in case of initialization as bean, to have a ServletContext
* as fallback to the context usually provided by a FilterConfig instance.
* @see org.springframework.web.context.ServletContextAware
* @see #getServletContext()
*/
public final void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}
/**
* Calls the <code>initFilterBean()</code> method that might
* contain custom initialization of a subclass.
* <p>Only relevant in case of initialization as bean, where the
* standard <code>init(FilterConfig)</code> method won't be called.
* @see #initFilterBean()
* @see #init(javax.servlet.FilterConfig)
*/
public void afterPropertiesSet() throws ServletException {
initFilterBean();
}
/**
* Subclasses can invoke this method to specify that this property
* (which must match a JavaBean property they expose) is mandatory,
* and must be supplied as a config parameter. This should be called
* from the constructor of a subclass.
* <p>This method is only relevant in case of traditional initialization
* driven by a FilterConfig instance.
* @param property name of the required property
*/
protected final void addRequiredProperty(String property) {
this.requiredProperties.add(property);
}
/**
* Standard way of initializing this filter.
* Map config parameters onto bean properties of this filter, and
* invoke subclass initialization.
* @param filterConfig the configuration for this filter
* @throws ServletException if bean properties are invalid (or required
* properties are missing), or if subclass initialization fails.
* @see #initFilterBean
*/
public final void init(FilterConfig filterConfig) throws ServletException {
Assert.notNull(filterConfig, "FilterConfig must not be null");
if (logger.isDebugEnabled()) {
logger.debug("Initializing filter '" + filterConfig.getFilterName() + "'");
}
this.filterConfig = filterConfig;
// Set bean properties from init parameters.
try {
PropertyValues pvs = new FilterConfigPropertyValues(filterConfig, this.requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
ResourceLoader resourceLoader = new ServletContextResourceLoader(filterConfig.getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader));
initBeanWrapper(bw);
bw.setPropertyValues(pvs, true);
}
catch (BeansException ex) {
String msg = "Failed to set bean properties on filter '" +
filterConfig.getFilterName() + "': " + ex.getMessage();
logger.error(msg, ex);
throw new NestedServletException(msg, ex);
}
// Let subclasses do whatever initialization they like.
initFilterBean();
if (logger.isDebugEnabled()) {
logger.debug("Filter '" + filterConfig.getFilterName() + "' configured successfully");
}
}
/**
* Initialize the BeanWrapper for this GenericFilterBean,
* possibly with custom editors.
* <p>This default implementation is empty.
* @param bw the BeanWrapper to initialize
* @throws BeansException if thrown by BeanWrapper methods
* @see org.springframework.beans.BeanWrapper#registerCustomEditor
*/
protected void initBeanWrapper(BeanWrapper bw) throws BeansException {
}
/**
* Make the FilterConfig of this filter available, if any.
* Analogous to GenericServlet's <code>getServletConfig()</code>.
* <p>Public to resemble the <code>getFilterConfig()</code> method
* of the Servlet Filter version that shipped with WebLogic 6.1.
* @return the FilterConfig instance, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletConfig()
*/
public final FilterConfig getFilterConfig() {
return this.filterConfig;
}
/**
* Make the name of this filter available to subclasses.
* Analogous to GenericServlet's <code>getServletName()</code>.
* <p>Takes the FilterConfig's filter name by default.
* If initialized as bean in a Spring application context,
* it falls back to the bean name as defined in the bean factory.
* @return the filter name, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletName()
* @see javax.servlet.FilterConfig#getFilterName()
* @see #setBeanName
*/
protected final String getFilterName() {
return (this.filterConfig != null ? this.filterConfig.getFilterName() : this.beanName);
}
/**
* Make the ServletContext of this filter available to subclasses.
* Analogous to GenericServlet's <code>getServletContext()</code>.
* <p>Takes the FilterConfig's ServletContext by default.
* If initialized as bean in a Spring application context,
* it falls back to the ServletContext that the bean factory runs in.
* @return the ServletContext instance, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletContext()
* @see javax.servlet.FilterConfig#getServletContext()
* @see #setServletContext
*/
protected final ServletContext getServletContext() {
return (this.filterConfig != null ? this.filterConfig.getServletContext() : this.servletContext);
}
/**
* Subclasses may override this to perform custom initialization.
* All bean properties of this filter will have been set before this
* method is invoked.
* <p>Note: This method will be called from standard filter initialization
* as well as filter bean initialization in a Spring application context.
* Filter name and ServletContext will be available in both cases.
* <p>This default implementation is empty.
* @throws ServletException if subclass initialization fails
* @see #getFilterName()
* @see #getServletContext()
*/
protected void initFilterBean() throws ServletException {
}
/**
* Subclasses may override this to perform custom filter shutdown.
* <p>Note: This method will be called from standard filter destruction
* as well as filter bean destruction in a Spring application context.
* <p>This default implementation is empty.
*/
public void destroy() {
}
/**
* PropertyValues implementation created from FilterConfig init parameters.
*/
private static class FilterConfigPropertyValues extends MutablePropertyValues {
/**
* Create new FilterConfigPropertyValues.
* @param config FilterConfig we'll use to take PropertyValues from
* @param requiredProperties set of property names we need, where
* we can't accept default values
* @throws ServletException if any required properties are missing
*/
public FilterConfigPropertyValues(FilterConfig config, Set requiredProperties)
throws ServletException {
Set missingProps = (requiredProperties != null && !requiredProperties.isEmpty()) ?
new HashSet(requiredProperties) : null;
Enumeration en = config.getInitParameterNames();
while (en.hasMoreElements()) {
String property = (String) en.nextElement();
Object value = config.getInitParameter(property);
addPropertyValue(new PropertyValue(property, value));
if (missingProps != null) {
missingProps.remove(property);
}
}
// Fail if we are still missing properties.
if (missingProps != null && missingProps.size() > 0) {
throw new ServletException(
"Initialization from FilterConfig for filter '" + config.getFilterName() +
"' failed; the following required properties were missing: " +
StringUtils.collectionToDelimitedString(missingProps, ", "));
}
}
}
}