Creates HandlerDiscoverer to dynamically load HandlerFunctions

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/config/GatewayMvcPropertiesBeanDefinitionRegistrar.java

@@ -17,6 +17,7 @@
 package org.springframework.cloud.gateway.server.mvc.config;
 
 import java.lang.reflect.Method;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
@@ -32,6 +33,7 @@ import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.cloud.gateway.server.mvc.common.MvcUtils;
 import org.springframework.cloud.gateway.server.mvc.filter.FilterDiscoverer;
+import org.springframework.cloud.gateway.server.mvc.handler.HandlerDiscoverer;
 import org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions;
 import org.springframework.cloud.gateway.server.mvc.invoke.InvocationContext;
 import org.springframework.cloud.gateway.server.mvc.invoke.OperationArgumentResolver;
@@ -65,10 +67,12 @@ public class GatewayMvcPropertiesBeanDefinitionRegistrar implements ImportBeanDe
 
 	private final Environment env;
 
-	private final PredicateDiscoverer predicateDiscoverer = new PredicateDiscoverer();
-
 	private final FilterDiscoverer filterDiscoverer = new FilterDiscoverer();
 
+	private final HandlerDiscoverer handlerDiscoverer = new HandlerDiscoverer();
+
+	private final PredicateDiscoverer predicateDiscoverer = new PredicateDiscoverer();
+
 	private final ParameterValueMapper parameterValueMapper = new ConversionServiceParameterValueMapper();
 
 	private final Binder binder;
@@ -106,15 +110,19 @@ public class GatewayMvcPropertiesBeanDefinitionRegistrar implements ImportBeanDe
 
 		RouterFunctions.Builder builder = route();
 
-		// TODO: cache, externalize?
+		MultiValueMap<String, OperationMethod> handlerOperations = handlerDiscoverer.getOperations();
+		// TODO: cache?
 		// translate handlerFunction
 		String scheme = routeProperties.getUri().getScheme();
-		Method handlerFunctionMethod = ReflectionUtils.findMethod(HandlerFunctions.class, scheme);
-		if (handlerFunctionMethod == null) {
+		Optional<OperationMethod> handlerOperationMethod = handlerOperations.get(scheme.toLowerCase()).stream()
+				.filter(operationMethod -> matchOperation(operationMethod, Collections.emptyMap())).findFirst();
+		if (handlerOperationMethod.isEmpty()) {
 			throw new IllegalStateException("Unable to find HandlerFunction for scheme: " + scheme);
 		}
-		HandlerFunction<ServerResponse> handlerFunction = (HandlerFunction) ReflectionUtils
-				.invokeMethod(handlerFunctionMethod, null);
+		ReflectiveOperationInvoker operationInvoker = new ReflectiveOperationInvoker(handlerOperationMethod.get(),
+				this.parameterValueMapper);
+		InvocationContext context = new InvocationContext(Collections.emptyMap(), trueNullOperationArgumentResolver);
+		HandlerFunction<ServerResponse> handlerFunction = operationInvoker.invoke(context);
 
 		// translate predicates
 		MultiValueMap<String, OperationMethod> predicateOperations = predicateDiscoverer.getOperations();

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerDiscoverer.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2013-2023 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.
+ * 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.cloud.gateway.server.mvc.handler;
+
+import org.springframework.cloud.gateway.server.mvc.common.AbstractGatewayDiscoverer;
+import org.springframework.web.servlet.function.HandlerFunction;
+
+public class HandlerDiscoverer extends AbstractGatewayDiscoverer {
+
+	@Override
+	public void discover() {
+		doDiscover(HandlerSupplier.class, HandlerFunction.class);
+	}
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerFunctionsHandlerSupplier.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2013-2023 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.
+ * 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.cloud.gateway.server.mvc.handler;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Collection;
+
+public class HandlerFunctionsHandlerSupplier implements HandlerSupplier {
+
+	@Override
+	public Collection<Method> get() {
+		return Arrays.asList(HandlerFunctions.class.getMethods());
+	}
+
+}

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/HandlerSupplier.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2013-2023 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.
+ * 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.cloud.gateway.server.mvc.handler;
+
+import java.lang.reflect.Method;
+import java.util.Collection;
+import java.util.function.Supplier;
+
+public interface HandlerSupplier extends Supplier<Collection<Method>> {
+
+}

spring-cloud-gateway-server-mvc/src/main/resources/META-INF/spring.factories

@@ -1,6 +1,9 @@
 org.springframework.cloud.gateway.server.mvc.filter.FilterSupplier=\
   org.springframework.cloud.gateway.server.mvc.filter.FilterFunctionsFilterSupplier
 
+org.springframework.cloud.gateway.server.mvc.handler.HandlerSupplier=\
+  org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctionsHandlerSupplier
+
 org.springframework.cloud.gateway.server.mvc.predicate.PredicateSupplier=\
   org.springframework.cloud.gateway.server.mvc.predicate.MvcPredicateSupplier,\
   org.springframework.cloud.gateway.server.mvc.predicate.GatewayPredicateSupplier