Introduce a public constant for the WebServerStartStopLifecycle's phase

This commit also moves the constant for the phase of
WebServerGracefulShutdownLifecycle to WebServerApplicationContext.

Closes gh-45572

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/server/ChildManagementContextInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -34,7 +34,6 @@
 import org.springframework.boot.context.event.ApplicationFailedEvent;
 import org.springframework.boot.web.context.ConfigurableWebServerApplicationContext;
 import org.springframework.boot.web.context.WebServerApplicationContext;
-import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.ApplicationEvent;
@@ -115,7 +114,7 @@ public boolean isRunning() {
 
 	@Override
 	public int getPhase() {
-		return WebServerGracefulShutdownLifecycle.SMART_LIFECYCLE_PHASE - 512;
+		return WebServerApplicationContext.GRACEFUL_SHUTDOWN_PHASE - 512;
 	}
 
 	@Override

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/context/WebServerApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -18,6 +18,7 @@
 
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.ApplicationContext;
+import org.springframework.context.SmartLifecycle;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -29,6 +30,20 @@
  */
 public interface WebServerApplicationContext extends ApplicationContext {
 
+	/**
+	 * {@link SmartLifecycle#getPhase() SmartLifecycle phase} in which graceful shutdown
+	 * of the web server is performed.
+	 * @since 4.0.0
+	 */
+	int GRACEFUL_SHUTDOWN_PHASE = SmartLifecycle.DEFAULT_PHASE - 1024;
+
+	/**
+	 * {@link SmartLifecycle#getPhase() SmartLifecycle phase} in which starting and
+	 * stopping of the web server is performed.
+	 * @since 4.0.0
+	 */
+	int START_STOP_LIFECYCLE_PHASE = GRACEFUL_SHUTDOWN_PHASE - 1024;
+
 	/**
 	 * Returns the {@link WebServer} that was created by the context or {@code null} if
 	 * the server has not yet been created.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/context/WebServerGracefulShutdownLifecycle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -30,7 +30,10 @@ public final class WebServerGracefulShutdownLifecycle implements SmartLifecycle
 	/**
 	 * {@link SmartLifecycle#getPhase() SmartLifecycle phase} in which graceful shutdown
 	 * of the web server is performed.
+	 * @deprecated as of 4.0.0 in favor of
+	 * {@link WebServerApplicationContext#GRACEFUL_SHUTDOWN_PHASE}
 	 */
+	@Deprecated(since = "4.0.0", forRemoval = true)
 	public static final int SMART_LIFECYCLE_PHASE = SmartLifecycle.DEFAULT_PHASE - 1024;
 
 	private final WebServer webServer;
@@ -69,7 +72,7 @@ public boolean isRunning() {
 
 	@Override
 	public int getPhase() {
-		return SMART_LIFECYCLE_PHASE;
+		return WebServerApplicationContext.GRACEFUL_SHUTDOWN_PHASE;
 	}
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/WebServerStartStopLifecycle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -16,7 +16,7 @@
 
 package org.springframework.boot.web.reactive.context;
 
-import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
+import org.springframework.boot.web.context.WebServerApplicationContext;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.SmartLifecycle;
 
@@ -55,7 +55,7 @@ public boolean isRunning() {
 
 	@Override
 	public int getPhase() {
-		return WebServerGracefulShutdownLifecycle.SMART_LIFECYCLE_PHASE - 1024;
+		return WebServerApplicationContext.START_STOP_LIFECYCLE_PHASE;
 	}
 
 }

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/WebServerStartStopLifecycle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -16,7 +16,7 @@
 
 package org.springframework.boot.web.servlet.context;
 
-import org.springframework.boot.web.context.WebServerGracefulShutdownLifecycle;
+import org.springframework.boot.web.context.WebServerApplicationContext;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.SmartLifecycle;
 
@@ -60,7 +60,7 @@ public boolean isRunning() {
 
 	@Override
 	public int getPhase() {
-		return WebServerGracefulShutdownLifecycle.SMART_LIFECYCLE_PHASE - 1024;
+		return WebServerApplicationContext.START_STOP_LIFECYCLE_PHASE;
 	}
 
 }