Add convenient WebAppInitializer base classes
This commit introduces three abstract WebApplicationInitializers, to be used in the typical setup of a Spring-based web application. - AbstractContextLoaderInitializer provides an abstract base class for registering a ContextLoaderListener. - AbstractDispatcherServletInitializer provides an abstract base class for registering a DispatcherServlet, with an optional root context. - AbstractAnnotationConfigDispatcherServletInitializer provides an abstract base class for registering a DispatcherServlet and optional ContextLoaderListener based on annotated (e.g. @Configuration) classes. Issue: SPR-9300
This commit is contained in:
Arjen Poutsma
committed by
Chris Beams
Chris Beams
parent
37e024c6eb
commit
f64c13ad2e
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/*
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* Copyright 2002-2012 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.web.servlet.support;
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import org.springframework.util.Assert;
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import org.springframework.util.ObjectUtils;
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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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/**
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* Base class for {@link org.springframework.web.WebApplicationInitializer
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* WebApplicationInitializer} implementations that register a {@link
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* org.springframework.web.servlet.DispatcherServlet DispatcherServlet}
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* configured with annotated classes, e.g. Spring's {@link
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* org.springframework.context.annotation.Configuration @Configuration} classes.
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*
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* <p>Concrete implementations are required to implement {@link #getRootConfigClasses()},
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* {@link #getServletConfigClasses()}, as well as {@link #getServletMappings()}. Further
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* template and customization methods are provided by {@link
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* AbstractDispatcherServletInitializer}.
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*
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* @author Arjen Poutsma
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* @author Chris Beams
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* @since 3.2
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*/
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public abstract class AbstractAnnotationConfigDispatcherServletInitializer
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extends AbstractDispatcherServletInitializer {
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/**
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* {@inheritDoc}
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* <p>This implementation creates an {@link AnnotationConfigWebApplicationContext},
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* providing it the annotated classes returned by {@link #getRootConfigClasses()}.
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* Returns {@code null} if {@link #getRootConfigClasses()} returns {@code null}.
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*/
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@Override
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protected WebApplicationContext createRootApplicationContext() {
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Class<?>[] rootConfigClasses = this.getRootConfigClasses();
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if (!ObjectUtils.isEmpty(rootConfigClasses)) {
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AnnotationConfigWebApplicationContext rootAppContext =
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new AnnotationConfigWebApplicationContext();
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rootAppContext.register(rootConfigClasses);
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return rootAppContext;
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}
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else {
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return null;
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}
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}
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/**
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* {@inheritDoc}
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* <p>This implementation creates an {@link AnnotationConfigWebApplicationContext},
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* providing it the annotated classes returned by {@link #getServletConfigClasses()}.
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* @throws IllegalArgumentException if {@link #getServletConfigClasses()} returns
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* empty or {@code null}
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*/
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@Override
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protected WebApplicationContext createServletApplicationContext() {
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AnnotationConfigWebApplicationContext servletAppContext =
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new AnnotationConfigWebApplicationContext();
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Class<?>[] servletConfigClasses = this.getServletConfigClasses();
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Assert.notEmpty(servletConfigClasses,
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"getServletConfigClasses() did not return any configuration classes");
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servletAppContext.register(servletConfigClasses);
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return servletAppContext;
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}
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/**
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* Specify {@link org.springframework.context.annotation.Configuration @Configuration}
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* and/or {@link org.springframework.stereotype.Component @Component} classes to be
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* provided to the {@linkplain #createRootApplicationContext() root application context}.
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* @return the configuration classes for the root application context, or {@code null}
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* if creation and registration of a root context is not desired
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*/
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protected abstract Class<?>[] getRootConfigClasses();
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/**
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* Specify {@link org.springframework.context.annotation.Configuration @Configuration}
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* and/or {@link org.springframework.stereotype.Component @Component} classes to be
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* provided to the {@linkplain #createServletApplicationContext() dispatcher servlet
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* application context}.
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* @return the configuration classes for the dispatcher servlet application context
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* (may not be empty or {@code null}).
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*/
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protected abstract Class<?>[] getServletConfigClasses();
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}
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@@ -0,0 +1,129 @@
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/*
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* Copyright 2002-2012 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.web.servlet.support;
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import javax.servlet.ServletContext;
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import javax.servlet.ServletException;
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import javax.servlet.ServletRegistration;
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import org.springframework.util.Assert;
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import org.springframework.web.context.AbstractContextLoaderInitializer;
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import org.springframework.web.context.WebApplicationContext;
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import org.springframework.web.servlet.DispatcherServlet;
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/**
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* Base class for {@link org.springframework.web.WebApplicationInitializer
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* WebApplicationInitializer} implementations that register a {@link DispatcherServlet} in
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* the servlet context.
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*
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* <p>Concrete implementations are required to implement {@link
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* #createServletApplicationContext()}, as well as {@link #getServletMappings()}, both of
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* which gets invoked from {@link #registerDispatcherServlet(ServletContext)}. Further
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* customization can be achieved by overriding
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* {@link #customizeRegistration(ServletRegistration.Dynamic)}.
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*
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* <p>Because this class extends from {@link AbstractContextLoaderInitializer}, concrete
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* implementations are also required to implement {@link #createRootApplicationContext()}
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* to set up a parent "<strong>root</strong>" application context. If a root context is
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* not desired, implementations can simply return {@code null} in the
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* {@code createRootApplicationContext()} implementation.
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*
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* @author Arjen Poutsma
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* @author Chris Beams
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* @since 3.2
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*/
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public abstract class AbstractDispatcherServletInitializer
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extends AbstractContextLoaderInitializer {
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/**
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* The default servlet name. Can be customized by overriding {@link #getServletName}.
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*/
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public static final String DEFAULT_SERVLET_NAME = "dispatcher";
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@Override
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public void onStartup(ServletContext servletContext) throws ServletException {
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super.onStartup(servletContext);
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this.registerDispatcherServlet(servletContext);
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}
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/**
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* Register a {@link DispatcherServlet} against the given servlet context.
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* <p>This method will create a {@code DispatcherServlet} with the name returned by
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* {@link #getServletName()}, initializing it with the application context returned
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* from {@link #createServletApplicationContext()}, and mapping it to the patterns
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* returned from {@link #getServletMappings()}.
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* <p>Further customization can be achieved by overriding {@link
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* #customizeRegistration(ServletRegistration.Dynamic)}.
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* @param servletContext the context to register the servlet against
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*/
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protected void registerDispatcherServlet(ServletContext servletContext) {
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String servletName = this.getServletName();
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Assert.hasLength(servletName,
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"getServletName() may not return empty or null");
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WebApplicationContext servletAppContext = this.createServletApplicationContext();
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Assert.notNull(servletAppContext,
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"createServletApplicationContext() did not return an application " +
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"context for servlet [" + servletName + "]");
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DispatcherServlet dispatcherServlet = new DispatcherServlet(servletAppContext);
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ServletRegistration.Dynamic registration =
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servletContext.addServlet(servletName, dispatcherServlet);
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registration.setLoadOnStartup(1);
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registration.addMapping(getServletMappings());
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this.customizeRegistration(registration);
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}
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/**
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* Return the name under which the {@link DispatcherServlet} will be registered.
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* Defaults to {@link #DEFAULT_SERVLET_NAME}.
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* @see #registerDispatcherServlet(ServletContext)
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*/
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protected String getServletName() {
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return DEFAULT_SERVLET_NAME;
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}
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/**
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* Create a servlet application context to be provided to the {@code DispatcherServlet}.
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* <p>The returned context is delegated to Spring's
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* {@link DispatcherServlet#DispatcherServlet(WebApplicationContext)} As such, it
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* typically contains controllers, view resolvers, locale resolvers, and other
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* web-related beans.
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* @see #registerDispatcherServlet(ServletContext)
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*/
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protected abstract WebApplicationContext createServletApplicationContext();
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/**
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* Specify the servlet mapping(s) for the {@code DispatcherServlet}, e.g. '/', '/app',
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* etc.
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* @see #registerDispatcherServlet(ServletContext)
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*/
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protected abstract String[] getServletMappings();
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/**
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* Optionally perform further registration customization once
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* {@link #registerDispatcherServlet(ServletContext)} has completed.
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* @param registration the {@code DispatcherServlet} registration to be customized
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* @see #registerDispatcherServlet(ServletContext)
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*/
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protected void customizeRegistration(ServletRegistration.Dynamic registration) {
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}
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}
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