@ExceptionHandler support for non-@controller handlers

Closes gh-22619

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerExceptionResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -180,8 +180,16 @@ protected boolean shouldApplyTo(HttpServletRequest request, @Nullable Object han
 				}
 			}
 		}
-		// Else only apply if there are no explicit handler mappings.
-		return (this.mappedHandlers == null && this.mappedHandlerClasses == null);
+		return !hasHandlerMappings();
+	}
+
+	/**
+	 * Whether there are any handler mappings registered via
+	 * {@link #setMappedHandlers(Set)} or {@link #setMappedHandlerClasses(Class[])}.
+	 * @since 5.3
+	 */
+	protected boolean hasHandlerMappings() {
+		return (this.mappedHandlers != null || this.mappedHandlerClasses != null);
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/AbstractHandlerMethodExceptionResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -48,17 +48,31 @@ else if (handler instanceof HandlerMethod) {
 			handler = handlerMethod.getBean();
 			return super.shouldApplyTo(request, handler);
 		}
+		else if (hasGlobalExceptionHandlers() && hasHandlerMappings()) {
+			return super.shouldApplyTo(request, handler);
+		}
 		else {
 			return false;
 		}
 	}
 
+	/**
+	 * Whether this resolver has global exception handlers, e.g. not declared in
+	 * the same class as the {@code HandlerMethod} that raised the exception and
+	 * therefore can apply to any handler.
+	 * @since 5.3
+	 */
+	protected boolean hasGlobalExceptionHandlers() {
+		return false;
+	}
+
 	@Override
 	@Nullable
 	protected final ModelAndView doResolveException(
 			HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
 
-		return doResolveHandlerMethodException(request, response, (HandlerMethod) handler, ex);
+		HandlerMethod handlerMethod = (handler instanceof HandlerMethod ? (HandlerMethod) handler : null);
+		return doResolveHandlerMethodException(request, response, handlerMethod, ex);
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolver.java

@@ -380,6 +380,10 @@ protected List<HandlerMethodReturnValueHandler> getDefaultReturnValueHandlers()
 		return handlers;
 	}
 
+	@Override
+	protected boolean hasGlobalExceptionHandlers() {
+		return !this.exceptionHandlerAdviceCache.isEmpty();
+	}
 
 	/**
 	 * Find an {@code @ExceptionHandler} method and invoke it to handle the raised exception.

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolverTests.java

@@ -39,6 +39,7 @@
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.util.ClassUtils;
+import org.springframework.web.HttpRequestHandler;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.ResponseBody;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
@@ -51,6 +52,7 @@
 import org.springframework.web.servlet.FlashMap;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.servlet.mvc.support.RedirectAttributes;
+import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.testfixture.servlet.MockHttpServletResponse;
 import org.springframework.web.util.NestedServletException;
@@ -346,6 +348,22 @@ void resolveExceptionControllerAdviceAgainstProxy() throws Exception {
 		assertThat(this.response.getContentAsString()).isEqualTo("BasePackageTestExceptionResolver: IllegalStateException");
 	}
 
+	@Test // gh-22619
+	void resolveExceptionViaMappedHandler() throws Exception {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MyControllerAdviceConfig.class);
+		this.resolver.setMappedHandlerClasses(HttpRequestHandler.class);
+		this.resolver.setApplicationContext(ctx);
+		this.resolver.afterPropertiesSet();
+
+		IllegalStateException ex = new IllegalStateException();
+		ResourceHttpRequestHandler handler = new ResourceHttpRequestHandler();
+		ModelAndView mav = this.resolver.resolveException(this.request, this.response, handler, ex);
+
+		assertThat(mav).as("Exception was not handled").isNotNull();
+		assertThat(mav.isEmpty()).isTrue();
+		assertThat(this.response.getContentAsString()).isEqualTo("DefaultTestExceptionResolver: IllegalStateException");
+	}
+
 
 	private void assertMethodProcessorCount(int resolverCount, int handlerCount) {
 		assertThat(this.resolver.getArgumentResolvers().getResolvers().size()).isEqualTo(resolverCount);