org.springframework.messaging.handler.annotation.support.HeaderMethodArgumentResolver.java Source code

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Here is the source code for org.springframework.messaging.handler.annotation.support.HeaderMethodArgumentResolver.java

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/*
 * Copyright 2002-2014 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
 *
 *      http://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.support;

import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.MethodParameter;
import org.springframework.core.convert.ConversionService;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHandlingException;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.messaging.support.NativeMessageHeaderAccessor;
import org.springframework.util.Assert;

/**
 * Resolves method parameters annotated with {@link Header @Header}.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {

    private static final Log logger = LogFactory.getLog(HeaderMethodArgumentResolver.class);

    public HeaderMethodArgumentResolver(ConversionService cs, ConfigurableBeanFactory beanFactory) {
        super(cs, beanFactory);
    }

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.hasParameterAnnotation(Header.class);
    }

    @Override
    protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
        Header annotation = parameter.getParameterAnnotation(Header.class);
        Assert.state(annotation != null, "No Header annotation");
        return new HeaderNamedValueInfo(annotation);
    }

    @Override
    @Nullable
    protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name)
            throws Exception {

        Object headerValue = message.getHeaders().get(name);
        Object nativeHeaderValue = getNativeHeaderValue(message, name);

        if (headerValue != null && nativeHeaderValue != null) {
            if (logger.isWarnEnabled()) {
                logger.warn("Message headers contain two values for the same header '" + name + "', "
                        + "one in the top level header map and a second in the nested map with native headers. "
                        + "Using the value from top level map. "
                        + "Use 'nativeHeader.myHeader' to resolve to the value from the nested native header map.");
            }
        }

        return (headerValue != null ? headerValue : nativeHeaderValue);
    }

    @Nullable
    private Object getNativeHeaderValue(Message<?> message, String name) {
        Map<String, List<String>> nativeHeaders = getNativeHeaders(message);
        if (name.startsWith("nativeHeaders.")) {
            name = name.substring("nativeHeaders.".length());
        }
        if (nativeHeaders == null || !nativeHeaders.containsKey(name)) {
            return null;
        }
        List<?> nativeHeaderValues = nativeHeaders.get(name);
        return (nativeHeaderValues.size() == 1 ? nativeHeaderValues.get(0) : nativeHeaderValues);
    }

    @SuppressWarnings("unchecked")
    private Map<String, List<String>> getNativeHeaders(Message<?> message) {
        return (Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
    }

    @Override
    protected void handleMissingValue(String headerName, MethodParameter parameter, Message<?> message) {
        throw new MessageHandlingException(message, "Missing header '" + headerName
                + "' for method parameter type [" + parameter.getParameterType() + "]");
    }

    private static class HeaderNamedValueInfo extends NamedValueInfo {

        private HeaderNamedValueInfo(Header annotation) {
            super(annotation.name(), annotation.required(), annotation.defaultValue());
        }
    }

}