org.springframework.integration.handler.support.PayloadsArgumentResolver.java Source code

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Here is the source code for org.springframework.integration.handler.support.PayloadsArgumentResolver.java

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/*
 * Copyright 2017-2019 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.integration.handler.support;

import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.springframework.core.MethodParameter;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.expression.Expression;
import org.springframework.integration.annotation.Payloads;
import org.springframework.integration.util.AbstractExpressionEvaluator;
import org.springframework.messaging.Message;
import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * The {@link HandlerMethodArgumentResolver} for resolving a {@link Collection}
 * of {@code payloads} or expression against each {@code payload}.
 * <p>
 * IMPORTANT: The {@link Message} for argument resolution must contain a {@code payload}
 * as {@link Collection} of {@link Message}s.
 *
 * @author Artem Bilan
 *
 * @since 5.0
 */
public class PayloadsArgumentResolver extends AbstractExpressionEvaluator implements HandlerMethodArgumentResolver {

    private final Map<MethodParameter, Expression> expressionCache = new HashMap<>();

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

    @Override
    @SuppressWarnings("unchecked")
    public Object resolveArgument(MethodParameter parameter, Message<?> message) {
        Object payload = message.getPayload();
        Assert.state(payload instanceof Collection,
                "This Argument Resolver support only messages with payload as Collection<Message<?>>");
        Collection<Message<?>> messages = (Collection<Message<?>>) payload;

        if (!this.expressionCache.containsKey(parameter)) {
            Payloads payloads = parameter.getParameterAnnotation(Payloads.class);
            String expression = payloads.value(); // NOSONAR never null - supportsParameter()
            if (StringUtils.hasText(expression)) {
                this.expressionCache.put(parameter,
                        EXPRESSION_PARSER.parseExpression("![payload." + expression + "]"));
            } else {
                this.expressionCache.put(parameter, null);
            }

        }

        Expression expression = this.expressionCache.get(parameter);
        if (expression != null) {
            return evaluateExpression(expression, messages, parameter.getParameterType());
        } else {
            List<?> payloads = messages.stream().map(Message::getPayload).collect(Collectors.toList());

            return getEvaluationContext().getTypeConverter().convertValue(payloads,
                    TypeDescriptor.forObject(payloads), TypeDescriptor.valueOf(parameter.getParameterType()));
        }
    }

}