spring MessageMappingReflectiveProcessor 源码

spring MessageMappingReflectiveProcessor 代码

文件路径：/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/MessageMappingReflectiveProcessor.java

/*
 * Copyright 2002-2022 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.messaging.handler.annotation;

import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.lang.reflect.Type;
import java.security.Principal;

import org.springframework.aot.hint.ExecutableMode;
import org.springframework.aot.hint.ReflectionHints;
import org.springframework.aot.hint.annotation.ReflectiveProcessor;
import org.springframework.context.aot.BindingReflectionHintsRegistrar;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.support.MessageHeaderAccessor;

/**
 * {@link ReflectiveProcessor} implementation for {@link MessageMapping}
 * annotated types. On top of registering reflection hints for invoking
 * the annotated method, this implementation handles:
 * <ul>
 *     <li>Return types.</li>
 *     <li>Parameters identified as potential payload.</li>
 *     <li>{@link Message} parameters.</li>
 * </ul>
 *
 * @author Sebastien Deleuze
 * @since 6.0
 */
class MessageMappingReflectiveProcessor implements ReflectiveProcessor {

	private final BindingReflectionHintsRegistrar bindingRegistrar = new BindingReflectionHintsRegistrar();

	@Override
	public void registerReflectionHints(ReflectionHints hints, AnnotatedElement element) {
		if (element instanceof Class<?> type) {
			registerTypeHints(hints, type);
		}
		else if (element instanceof Method method) {
			registerMethodHints(hints, method);
		}
	}

	protected void registerTypeHints(ReflectionHints hints, Class<?> type) {
		hints.registerType(type, hint -> {});
	}

	protected void registerMethodHints(ReflectionHints hints, Method method) {
		hints.registerMethod(method, hint -> hint.setModes(ExecutableMode.INVOKE));
		registerParameterHints(hints, method);
		registerReturnValueHints(hints, method);
	}

	protected void registerParameterHints(ReflectionHints hints, Method method) {
		hints.registerMethod(method, hint -> hint.setModes(ExecutableMode.INVOKE));
		for (Parameter parameter : method.getParameters()) {
			MethodParameter methodParameter = MethodParameter.forParameter(parameter);
			if (Message.class.isAssignableFrom(methodParameter.getParameterType())) {
				this.bindingRegistrar.registerReflectionHints(hints, getMessageType(methodParameter));
			}
			else if (couldBePayload(methodParameter)) {
				this.bindingRegistrar.registerReflectionHints(hints, methodParameter.getGenericParameterType());
			}
		}
	}

	protected boolean couldBePayload(MethodParameter methodParameter) {
		return !methodParameter.hasParameterAnnotation(DestinationVariable.class) &&
				!methodParameter.hasParameterAnnotation(Header.class) &&
				!methodParameter.hasParameterAnnotation(Headers.class) &&
				!MessageHeaders.class.isAssignableFrom(methodParameter.getParameterType()) &&
				!MessageHeaderAccessor.class.isAssignableFrom(methodParameter.getParameterType()) &&
				!Principal.class.isAssignableFrom(methodParameter.nestedIfOptional().getNestedParameterType());
	}

	protected void registerReturnValueHints(ReflectionHints hints, Method method) {
		MethodParameter returnType = MethodParameter.forExecutable(method, -1);
		this.bindingRegistrar.registerReflectionHints(hints, returnType.getGenericParameterType());
	}

	@Nullable
	protected Type getMessageType(MethodParameter parameter) {
		MethodParameter nestedParameter = parameter.nested();
		return (nestedParameter.getNestedParameterType() == nestedParameter.getParameterType() ? null : nestedParameter.getNestedParameterType());
	}
}

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