Add AbstractHttpSessionApplicationInitializer
This reduces the boilerplate code required to register Spring Session with the servlet container. Fixes gh-43
This commit is contained in:
Rob Winch
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/*
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* Copyright 2002-2013 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.session.web.context;
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import java.util.Arrays;
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import java.util.EnumSet;
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import javax.servlet.DispatcherType;
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import javax.servlet.Filter;
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import javax.servlet.FilterRegistration.Dynamic;
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import javax.servlet.ServletContext;
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import javax.servlet.ServletException;
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import org.springframework.context.ApplicationContext;
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import org.springframework.core.Conventions;
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import org.springframework.core.Ordered;
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import org.springframework.core.annotation.Order;
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import org.springframework.util.Assert;
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import org.springframework.web.WebApplicationInitializer;
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import org.springframework.web.context.AbstractContextLoaderInitializer;
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import org.springframework.web.context.ContextLoaderListener;
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import org.springframework.web.context.WebApplicationContext;
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import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
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import org.springframework.web.filter.DelegatingFilterProxy;
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/**
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* Registers the {@link DelegatingFilterProxy} to use the
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* springSessionRepositoryFilter before any other registered {@link Filter}. When
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* used with {@link #AbstractHttpSessionApplicationInitializer(Class...)}, it
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* will also register a {@link ContextLoaderListener}. When used with
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* {@link #AbstractHttpSessionApplicationInitializer()}, this class is typically
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* used in addition to a subclass of {@link AbstractContextLoaderInitializer}.
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*
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* <p>
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* By default the {@link DelegatingFilterProxy} is registered with support for
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* asynchronous requests, but can be enabled by overriding {@link #isAsyncSecuritySupported()} and
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* {@link #getSecurityDispatcherTypes()}.
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* </p>
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*
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* <p>
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* Additional configuration before and after the springSecurityFilterChain can
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* be added by overriding
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* {@link #afterSpringSecurityFilterChain(ServletContext)}.
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* </p>
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*
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*
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* <h2>Caveats</h2>
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* <p>
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* Subclasses of AbstractDispatcherServletInitializer will register their
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* filters before any other {@link Filter}. This means that you will typically
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* want to ensure subclasses of AbstractDispatcherServletInitializer are invoked
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* first. This can be done by ensuring the {@link Order} or {@link Ordered} of
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* AbstractDispatcherServletInitializer are sooner than subclasses of
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* {@link AbstractSecurityWebApplicationInitializer}.
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* </p>
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*
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* @author Rob Winch
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*
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*/
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@Order(100)
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public abstract class AbstractHttpSessionApplicationInitializer implements WebApplicationInitializer {
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private static final String SERVLET_CONTEXT_PREFIX = "org.springframework.web.servlet.FrameworkServlet.CONTEXT.";
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public static final String DEFAULT_FILTER_NAME = "springSessionRepositoryFilter";
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private final Class<?>[] configurationClasses;
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/**
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* Creates a new instance that assumes the Spring Session configuration is
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* loaded by some other means than this class. For example, a user might
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* create a {@link ContextLoaderListener} using a subclass of
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* {@link AbstractContextLoaderInitializer}.
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*
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* @see ContextLoaderListener
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*/
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protected AbstractHttpSessionApplicationInitializer() {
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this.configurationClasses = null;
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}
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/**
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* Creates a new instance that will instantiate the
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* {@link ContextLoaderListener} with the specified classes.
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*
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* @param configurationClasses
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*/
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protected AbstractHttpSessionApplicationInitializer(Class<?>... configurationClasses) {
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this.configurationClasses = configurationClasses;
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}
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@Override
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public void onStartup(ServletContext servletContext)
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throws ServletException {
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beforeSessionRepositoryFilter(servletContext);
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if(configurationClasses != null) {
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AnnotationConfigWebApplicationContext rootAppContext = new AnnotationConfigWebApplicationContext();
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rootAppContext.register(configurationClasses);
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servletContext.addListener(new ContextLoaderListener(rootAppContext));
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}
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insertSessionRepositoryFilter(servletContext);
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afterSessionRepositoryFilter(servletContext);
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}
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/**
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* Registers the springSessionRepositoryFilter
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* @param servletContext the {@link ServletContext}
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*/
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private void insertSessionRepositoryFilter(ServletContext servletContext) {
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String filterName = DEFAULT_FILTER_NAME;
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DelegatingFilterProxy springSessionRepositoryFilter = new DelegatingFilterProxy(filterName);
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String contextAttribute = getWebApplicationContextAttribute();
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if(contextAttribute != null) {
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springSessionRepositoryFilter.setContextAttribute(contextAttribute);
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}
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registerFilter(servletContext, true, filterName, springSessionRepositoryFilter);
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}
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/**
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* Inserts the provided {@link Filter}s before existing {@link Filter}s
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* using default generated names, {@link #getSessionDispatcherTypes()}, and
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* {@link #isAsyncSessionSupported()}.
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*
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* @param servletContext
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* the {@link ServletContext} to use
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* @param filters
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* the {@link Filter}s to register
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*/
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protected final void insertFilters(ServletContext servletContext,Filter... filters) {
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registerFilters(servletContext, true, filters);
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}
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/**
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* Inserts the provided {@link Filter}s after existing {@link Filter}s
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* using default generated names, {@link #getSessionDispatcherTypes()}, and
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* {@link #isAsyncSessionSupported()}.
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*
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* @param servletContext
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* the {@link ServletContext} to use
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* @param filters
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* the {@link Filter}s to register
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*/
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protected final void appendFilters(ServletContext servletContext,Filter... filters) {
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registerFilters(servletContext, false, filters);
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}
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/**
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* Registers the provided {@link Filter}s using default generated names,
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* {@link #getSessionDispatcherTypes()}, and
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* {@link #isAsyncSessionSupported()}.
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*
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* @param servletContext
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* the {@link ServletContext} to use
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* @param insertBeforeOtherFilters
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* if true, will insert the provided {@link Filter}s before other
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* {@link Filter}s. Otherwise, will insert the {@link Filter}s
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* after other {@link Filter}s.
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* @param filters
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* the {@link Filter}s to register
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*/
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private void registerFilters(ServletContext servletContext, boolean insertBeforeOtherFilters, Filter... filters) {
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Assert.notEmpty(filters, "filters cannot be null or empty");
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for(Filter filter : filters) {
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if(filter == null) {
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throw new IllegalArgumentException("filters cannot contain null values. Got " + Arrays.asList(filters));
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}
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String filterName = Conventions.getVariableName(filter);
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registerFilter(servletContext, insertBeforeOtherFilters, filterName, filter);
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}
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}
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/**
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* Registers the provided filter using the {@link #isAsyncSessionSupported()} and {@link #getSessionDispatcherTypes()}.
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*
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* @param servletContext
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* @param insertBeforeOtherFilters should this Filter be inserted before or after other {@link Filter}
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* @param filterName
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* @param filter
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*/
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private final void registerFilter(ServletContext servletContext, boolean insertBeforeOtherFilters, String filterName, Filter filter) {
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Dynamic registration = servletContext.addFilter(filterName, filter);
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if(registration == null) {
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throw new IllegalStateException("Duplicate Filter registration for '" + filterName +"'. Check to ensure the Filter is only configured once.");
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}
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registration.setAsyncSupported(isAsyncSessionSupported());
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EnumSet<DispatcherType> dispatcherTypes = getSessionDispatcherTypes();
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registration.addMappingForUrlPatterns(dispatcherTypes, !insertBeforeOtherFilters, "/*");
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}
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/**
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* Returns the {@link DelegatingFilterProxy#getContextAttribute()} or null
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* if the parent {@link ApplicationContext} should be used. The default
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* behavior is to use the parent {@link ApplicationContext}.
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*
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* <p>
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* If {@link #getDispatcherWebApplicationContextSuffix()} is non-null the
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* {@link WebApplicationContext} for the Dispatcher will be used. This means
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* the child {@link ApplicationContext} is used to look up the
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* springSessionRepositoryFilter bean.
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* </p>
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*
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* @return the {@link DelegatingFilterProxy#getContextAttribute()} or null
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* if the parent {@link ApplicationContext} should be used
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*/
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private String getWebApplicationContextAttribute() {
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String dispatcherServletName = getDispatcherWebApplicationContextSuffix();
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if(dispatcherServletName == null) {
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return null;
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}
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return SERVLET_CONTEXT_PREFIX + dispatcherServletName;
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}
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/**
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* Return the <servlet-name> to use the DispatcherServlet's
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* {@link WebApplicationContext} to find the {@link DelegatingFilterProxy}
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* or null to use the parent {@link ApplicationContext}.
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*
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* <p>
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* For example, if you are using AbstractDispatcherServletInitializer or
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* AbstractAnnotationConfigDispatcherServletInitializer and using the
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* provided Servlet name, you can return "dispatcher" from this method to
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* use the DispatcherServlet's {@link WebApplicationContext}.
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* </p>
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*
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* @return the <servlet-name> of the DispatcherServlet to use its
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* {@link WebApplicationContext} or null (default) to use the parent
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* {@link ApplicationContext}.
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*/
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protected String getDispatcherWebApplicationContextSuffix() {
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return null;
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}
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/**
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* Invoked before the springSessionRepositoryFilter is added.
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* @param servletContext the {@link ServletContext}
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*/
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protected void beforeSessionRepositoryFilter(ServletContext servletContext) {
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}
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/**
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* Invoked after the springSessionRepositoryFilter is added.
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* @param servletContext the {@link ServletContext}
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*/
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protected void afterSessionRepositoryFilter(ServletContext servletContext) {
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}
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/**
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* Get the {@link DispatcherType} for the springSessionRepositoryFilter.
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* @return
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*/
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protected EnumSet<DispatcherType> getSessionDispatcherTypes() {
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return EnumSet.of(DispatcherType.REQUEST, DispatcherType.ERROR, DispatcherType.ASYNC);
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}
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/**
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* Determine if the springSessionRepositoryFilter should be marked as supporting
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* asynch. Default is true.
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*
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* @return true if springSessionRepositoryFilter should be marked as supporting
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* asynch
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*/
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protected boolean isAsyncSessionSupported() {
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return true;
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}
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}
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