From d240e293db1e5834eff0338a06129fc3c8d75a71 Mon Sep 17 00:00:00 2001 From: Madhura Bhave Date: Tue, 8 Mar 2022 17:34:35 -0800 Subject: [PATCH] Document how to obtain ServletContext with an embedded container setup Closes gh-24561 --- .../features/developing-web-applications.adoc | 11 ++++++ .../applicationcontext/MyDemoBean.java | 36 +++++++++++++++++++ 2 files changed, 47 insertions(+) create mode 100644 spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingwebapplications/embeddedcontainer/applicationcontext/MyDemoBean.java diff --git a/spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/developing-web-applications.adoc b/spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/developing-web-applications.adoc index c9acd27279..6afd43e6d6 100644 --- a/spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/developing-web-applications.adoc +++ b/spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/developing-web-applications.adoc @@ -818,6 +818,17 @@ Usually a `TomcatServletWebServerFactory`, `JettyServletWebServerFactory`, or `U NOTE: You usually do not need to be aware of these implementation classes. Most applications are auto-configured, and the appropriate `ApplicationContext` and `ServletWebServerFactory` are created on your behalf. +In an embedded container setup, the `ServletContext` is set as part of server startup which happens during application context initialization. +Because of this beans in the `ApplicationContext` cannot be reliably initialized with a `ServletContext`. +One way to get around this is to inject `ApplicationContext` as a dependency of the bean and access the `ServletContext` only when it is needed. +Another way is to use a callback once the server has started. +This can be done using an `ApplicationListener` which listens for the `ApplicationStartedEvent` as follows: + +[source,java,indent=0,subs="verbatim"] +---- +include::{docs-java}/features/developingwebapplications/embeddedcontainer/applicationcontext/MyDemoBean.java[] +---- + [[features.developing-web-applications.embedded-container.customizing]] diff --git a/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingwebapplications/embeddedcontainer/applicationcontext/MyDemoBean.java b/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingwebapplications/embeddedcontainer/applicationcontext/MyDemoBean.java new file mode 100644 index 0000000000..7cb0e0f27e --- /dev/null +++ b/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingwebapplications/embeddedcontainer/applicationcontext/MyDemoBean.java @@ -0,0 +1,36 @@ +/* + * Copyright 2012-2022 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 + * + * https://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.boot.docs.features.developingwebapplications.embeddedcontainer.applicationcontext; + +import javax.servlet.ServletContext; + +import org.springframework.boot.context.event.ApplicationStartedEvent; +import org.springframework.context.ApplicationContext; +import org.springframework.context.ApplicationListener; +import org.springframework.web.context.WebApplicationContext; + +public class MyDemoBean implements ApplicationListener { + + private ServletContext servletContext; + + @Override + public void onApplicationEvent(ApplicationStartedEvent event) { + ApplicationContext applicationContext = event.getApplicationContext(); + this.servletContext = ((WebApplicationContext) applicationContext).getServletContext(); + } + +}