Set throwExceptionIfNoHandlerFound=true and deprecate

Closes gh-29491

framework-docs/modules/ROOT/pages/web/webmvc/mvc-ann-rest-exceptions.adoc

@@ -162,6 +162,10 @@ Spring MVC exceptions:
 | (default)
 |
 
+| `NoResourceFoundException`
+| (default)
+|
+
 | `TypeMismatchException`
 | (default)
 | `+{0}+` property name, `+{1}+` property value

framework-docs/modules/ROOT/pages/web/webmvc/mvc-servlet/sequence.adoc

@@ -62,8 +62,7 @@ initialization parameters (`init-param` elements) to the Servlet declaration in
   The exception can then be caught with a `HandlerExceptionResolver` (for example, by using an
   `@ExceptionHandler` controller method) and handled as any others.
 
-  By default, this is set to `false`, in which case the `DispatcherServlet` sets the
-  response status to 404 (NOT_FOUND) without raising an exception.
+  As of 6.1, this property is set to `true` and deprecated.
 
   Note that, if xref:web/webmvc/mvc-config/default-servlet-handler.adoc[default servlet handling]  is
   also configured, unresolved requests are always forwarded to the default servlet

spring-test/src/test/java/org/springframework/test/web/servlet/samples/client/standalone/ExceptionHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -156,7 +156,6 @@ class ExceptionHandlerTests {
 		void noHandlerFound() {
 			WebTestClient client = MockMvcWebTestClient.bindToController(new RestPersonController())
 					.controllerAdvice(RestGlobalExceptionHandler.class, RestPersonControllerExceptionHandler.class)
-					.dispatcherServletCustomizer(servlet -> servlet.setThrowExceptionIfNoHandlerFound(true))
 					.build();
 
 			client.get().uri("/bogus")

spring-test/src/test/java/org/springframework/test/web/servlet/samples/standalone/ExceptionHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -138,7 +138,6 @@ public class ExceptionHandlerTests {
 		void noHandlerFound() throws Exception {
 			standaloneSetup(RestPersonController.class)
 				.setControllerAdvice(RestGlobalExceptionHandler.class, RestPersonControllerExceptionHandler.class)
-				.addDispatcherServletCustomizer(servlet -> servlet.setThrowExceptionIfNoHandlerFound(true))
 				.build()
 				.perform(get("/bogus").accept(MediaType.APPLICATION_JSON))
 				.andExpect(status().isOk())

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

@@ -305,7 +305,7 @@ public class DispatcherServlet extends FrameworkServlet {
 	private boolean detectAllViewResolvers = true;
 
 	/** Throw a NoHandlerFoundException if no Handler was found to process this request? *.*/
-	private boolean throwExceptionIfNoHandlerFound = false;
+	private boolean throwExceptionIfNoHandlerFound = true;
 
 	/** Perform cleanup of request attributes after include request?. */
 	private boolean cleanupAfterInclude = true;
@@ -467,7 +467,12 @@ public class DispatcherServlet extends FrameworkServlet {
 	 * <p>Default is "false", meaning the DispatcherServlet sends a NOT_FOUND error through the
 	 * Servlet response.
 	 * @since 4.0
+	 * @deprecated as of 6.1 this property is set to {@code true} by default, and
+	 * should not need to be customized; in effect, {@link DispatcherServlet}
+	 * should always raise {@link NoHandlerFoundException} and allow it to be
+	 * handled through a {@link HandlerExceptionResolver}.
 	 */
+	@Deprecated(since = "6.1", forRemoval = true)
 	public void setThrowExceptionIfNoHandlerFound(boolean throwExceptionIfNoHandlerFound) {
 		this.throwExceptionIfNoHandlerFound = throwExceptionIfNoHandlerFound;
 	}

spring-webmvc/src/test/java/org/springframework/web/servlet/ComplexWebApplicationContext.java

@@ -150,20 +150,26 @@ public class ComplexWebApplicationContext extends StaticWebApplicationContext {
 		registerSingleton("myServlet", MyServlet.class);
 
 		pvs = new MutablePropertyValues();
-		pvs.add("order", "1");
+		pvs.add("order", "2");
 		pvs.add("exceptionMappings",
 				"java.lang.IllegalAccessException=failed2\n" +
 				"ServletRequestBindingException=failed3");
 		pvs.add("defaultErrorView", "failed0");
-		registerSingleton("exceptionResolver1", SimpleMappingExceptionResolver.class, pvs);
+		registerSingleton("exceptionResolver2", SimpleMappingExceptionResolver.class, pvs);
 
 		pvs = new MutablePropertyValues();
-		pvs.add("order", "0");
+		pvs.add("order", "1");
 		pvs.add("exceptionMappings", "java.lang.Exception=failed1");
 		pvs.add("mappedHandlers", ManagedList.of(new RuntimeBeanReference("anotherLocaleHandler")));
 		pvs.add("defaultStatusCode", "500");
 		pvs.add("defaultErrorView", "failed2");
-		registerSingleton("handlerExceptionResolver", SimpleMappingExceptionResolver.class, pvs);
+		registerSingleton("exceptionResolver1", SimpleMappingExceptionResolver.class, pvs);
+
+		pvs = new MutablePropertyValues();
+		pvs.add("order", "0");
+		pvs.add("exceptionMappings", "org.springframework.web.servlet.NoHandlerFoundException=notFound");
+		pvs.add("defaultStatusCode", "404");
+		registerSingleton("exceptionResolver0", SimpleMappingExceptionResolver.class, pvs);
 
 		registerSingleton("multipartResolver", MockMultipartResolver.class);
 		registerSingleton("testListener", TestApplicationListener.class);

spring-webmvc/src/test/java/org/springframework/web/servlet/DispatcherServletTests.java

@@ -591,7 +591,6 @@ public class DispatcherServletTests {
 		DispatcherServlet complexDispatcherServlet = new DispatcherServlet();
 		complexDispatcherServlet.setContextClass(SimpleWebApplicationContext.class);
 		complexDispatcherServlet.setNamespace("test");
-		complexDispatcherServlet.setThrowExceptionIfNoHandlerFound(true);
 		complexDispatcherServlet.init(new MockServletConfig(getServletContext(), "complex"));
 
 		MockHttpServletRequest request = new MockHttpServletRequest(getServletContext(), "GET", "/unknown");