org.springframework.integration.endpoint.ExpressionMessageProducerSupport.java Source code

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Here is the source code for org.springframework.integration.endpoint.ExpressionMessageProducerSupport.java

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/*
 * Copyright 2002-2019 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.endpoint;

import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.integration.expression.ExpressionUtils;
import org.springframework.util.Assert;

/**
 * A {@link MessageProducerSupport} sub-class that provides {@linkplain #payloadExpression}
 * evaluation with result as a payload for Message to send.
 *
 * @author David Turanski
 * @author Artem Bilan
 * @author Gary Russell
 * @since 2.1
 *
 */
public abstract class ExpressionMessageProducerSupport extends MessageProducerSupport {

    private volatile Expression payloadExpression;

    private volatile EvaluationContext evaluationContext;

    /**
     * @param payloadExpression the expression to use.
     * @since 4.3
     */
    public void setPayloadExpression(Expression payloadExpression) {
        this.payloadExpression = payloadExpression;
    }

    /**
     * @param payloadExpression the String in SpEL syntax.
     * @since 4.3
     */
    public void setPayloadExpressionString(String payloadExpression) {
        Assert.hasText(payloadExpression, "'payloadExpression' must not be empty");
        this.payloadExpression = EXPRESSION_PARSER.parseExpression(payloadExpression);
    }

    public void setIntegrationEvaluationContext(EvaluationContext evaluationContext) {
        this.evaluationContext = evaluationContext;
    }

    @Override
    protected void onInit() {
        super.onInit();
        if (this.evaluationContext == null) {
            this.evaluationContext = ExpressionUtils.createStandardEvaluationContext(this.getBeanFactory());
        }
    }

    protected Object evaluatePayloadExpression(Object payload) {
        Object evaluationResult = payload;
        if (this.payloadExpression != null) {
            evaluationResult = this.payloadExpression.getValue(this.evaluationContext, payload);
        }
        return evaluationResult;
    }

}