diff --git a/spring-boot-project/spring-boot-docs/src/docs/asciidoc/web/servlet.adoc b/spring-boot-project/spring-boot-docs/src/docs/asciidoc/web/servlet.adoc index f7dace780e..feb8099128 100644 --- a/spring-boot-project/spring-boot-docs/src/docs/asciidoc/web/servlet.adoc +++ b/spring-boot-project/spring-boot-docs/src/docs/asciidoc/web/servlet.adoc @@ -504,6 +504,17 @@ 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}/web/servlet/embeddedcontainer/applicationcontext/MyDemoBean.java[] +---- + [[web.servlet.embedded-container.customizing]] diff --git a/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/web/servlet/embeddedcontainer/applicationcontext/MyDemoBean.java b/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/web/servlet/embeddedcontainer/applicationcontext/MyDemoBean.java new file mode 100644 index 0000000000..cd421c8aab --- /dev/null +++ b/spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/web/servlet/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.web.servlet.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(); + } + +}