Align FilterRegistrationBean empty dispatcher type logic with FilterRegistration annotation

Closes gh-45130

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

@@ -31,6 +31,7 @@ import jakarta.servlet.ServletContext;
 
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 import org.springframework.web.filter.OncePerRequestFilter;
 
@@ -167,7 +168,7 @@ public abstract class AbstractFilterRegistrationBean<T extends Filter> extends D
 	 * @since 3.2.0
 	 */
 	public EnumSet<DispatcherType> determineDispatcherTypes() {
-		if (this.dispatcherTypes == null) {
+		if (CollectionUtils.isEmpty(this.dispatcherTypes)) {
 			T filter = getFilter();
 			if (ClassUtils.isPresent("org.springframework.web.filter.OncePerRequestFilter",
 					filter.getClass().getClassLoader()) && filter instanceof OncePerRequestFilter) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/AbstractFilterRegistrationBeanTests.java

@@ -25,14 +25,22 @@ import java.util.Map;
 
 import jakarta.servlet.DispatcherType;
 import jakarta.servlet.Filter;
+import jakarta.servlet.FilterChain;
 import jakarta.servlet.FilterRegistration;
 import jakarta.servlet.ServletContext;
 import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import jakarta.servlet.ServletResponse;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
+import org.springframework.web.filter.OncePerRequestFilter;
+
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatCode;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
@@ -47,6 +55,7 @@ import static org.mockito.Mockito.never;
  * Abstract base for {@link AbstractFilterRegistrationBean} tests.
  *
  * @author Phillip Webb
+ * @author Moritz Halbritter
  */
 @ExtendWith(MockitoExtension.class)
 abstract class AbstractFilterRegistrationBeanTests {
@@ -227,6 +236,42 @@ abstract class AbstractFilterRegistrationBeanTests {
 		}).doesNotThrowAnyException();
 	}
 
+	@Test
+	void shouldDetermineDispatcherTypesIfNotSet() {
+		AbstractFilterRegistrationBean<SimpleFilter> simpleFilter = new AbstractFilterRegistrationBean<>() {
+			@Override
+			public SimpleFilter getFilter() {
+				return new SimpleFilter();
+			}
+		};
+		assertThat(simpleFilter.determineDispatcherTypes()).containsExactly(DispatcherType.REQUEST);
+	}
+
+	@Test
+	void shouldDetermineDispatcherTypesForOncePerRequestFilters() {
+		AbstractFilterRegistrationBean<SimpleOncePerRequestFilter> simpleFilter = new AbstractFilterRegistrationBean<>() {
+			@Override
+			public SimpleOncePerRequestFilter getFilter() {
+				return new SimpleOncePerRequestFilter();
+			}
+		};
+		assertThat(simpleFilter.determineDispatcherTypes())
+			.containsExactlyInAnyOrderElementsOf(EnumSet.allOf(DispatcherType.class));
+	}
+
+	@Test
+	void shouldDetermineDispatcherTypesForSetDispatcherTypes() {
+		AbstractFilterRegistrationBean<SimpleFilter> simpleFilter = new AbstractFilterRegistrationBean<>() {
+			@Override
+			public SimpleFilter getFilter() {
+				return new SimpleFilter();
+			}
+		};
+		simpleFilter.setDispatcherTypes(DispatcherType.INCLUDE, DispatcherType.FORWARD);
+		assertThat(simpleFilter.determineDispatcherTypes()).containsExactlyInAnyOrder(DispatcherType.INCLUDE,
+				DispatcherType.FORWARD);
+	}
+
 	protected abstract Filter getExpectedFilter();
 
 	protected abstract AbstractFilterRegistrationBean<?> createFilterRegistrationBean(
@@ -238,4 +283,23 @@ abstract class AbstractFilterRegistrationBeanTests {
 		return bean;
 	}
 
+	private static final class SimpleFilter implements Filter {
+
+		@Override
+		public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
+
+		}
+
+	}
+
+	private static final class SimpleOncePerRequestFilter extends OncePerRequestFilter {
+
+		@Override
+		protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
+				FilterChain filterChain) {
+
+		}
+
+	}
+
 }

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/servlet/NoSpringWebFilterRegistrationBeanTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 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.
@@ -45,4 +45,9 @@ class NoSpringWebFilterRegistrationBeanTests extends AbstractFilterRegistrationB
 		return eq(this.filter);
 	}
 
+	@Override
+	void shouldDetermineDispatcherTypesForOncePerRequestFilters() {
+		// Disabled because OncePerRequestFilter isn't on the classpath
+	}
+
 }