org.springframework.integration.util.AbstractExpressionEvaluator.java Source code

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Here is the source code for org.springframework.integration.util.AbstractExpressionEvaluator.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.util;

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

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.expression.BeanFactoryResolver;
import org.springframework.core.convert.ConversionService;
import org.springframework.expression.EvaluationException;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.integration.expression.ExpressionUtils;
import org.springframework.integration.support.DefaultMessageBuilderFactory;
import org.springframework.integration.support.MessageBuilderFactory;
import org.springframework.integration.support.utils.IntegrationUtils;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;

/**
 * @author Mark Fisher
 * @author Dave Syer
 * @author Oleg Zhurakousky
 * @author Artem Bilan
 * @author Gary Russell
 *
 * @since 2.0
 */
public abstract class AbstractExpressionEvaluator implements BeanFactoryAware, InitializingBean {

    protected final Log logger = LogFactory.getLog(this.getClass()); // NOSONAR final

    protected static final ExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();

    private final BeanFactoryTypeConverter typeConverter = new BeanFactoryTypeConverter();

    private volatile StandardEvaluationContext evaluationContext;

    private volatile BeanFactory beanFactory;

    private volatile MessageBuilderFactory messageBuilderFactory = new DefaultMessageBuilderFactory();

    /**
     * Specify a BeanFactory in order to enable resolution via <code>@beanName</code> in the expression.
     */
    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
        this.typeConverter.setBeanFactory(beanFactory);
        if (this.evaluationContext != null && this.evaluationContext.getBeanResolver() == null) {
            this.evaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
        }
    }

    protected BeanFactory getBeanFactory() {
        return this.beanFactory;
    }

    public void setConversionService(ConversionService conversionService) {
        if (conversionService != null) {
            this.typeConverter.setConversionService(conversionService);
        }
    }

    protected MessageBuilderFactory getMessageBuilderFactory() {
        return this.messageBuilderFactory;
    }

    @Override
    public final void afterPropertiesSet() {
        getEvaluationContext();
        if (this.beanFactory != null) {
            this.messageBuilderFactory = IntegrationUtils.getMessageBuilderFactory(this.beanFactory);
        }

        onInit();
    }

    protected StandardEvaluationContext getEvaluationContext() {
        return getEvaluationContext(true);
    }

    /**
     * Emits a WARN log if the beanFactory field is null, unless the argument is false.
     * @param beanFactoryRequired set to false to suppress the warning.
     * @return The evaluation context.
     */
    protected final StandardEvaluationContext getEvaluationContext(boolean beanFactoryRequired) {
        if (this.evaluationContext == null) {
            if (this.beanFactory == null && !beanFactoryRequired) {
                this.evaluationContext = ExpressionUtils.createStandardEvaluationContext();
            } else {
                this.evaluationContext = ExpressionUtils.createStandardEvaluationContext(this.beanFactory);
            }
            this.evaluationContext.setTypeConverter(this.typeConverter);
            if (this.beanFactory != null) {
                ConversionService conversionService = IntegrationUtils.getConversionService(this.beanFactory);
                if (conversionService != null) {
                    this.typeConverter.setConversionService(conversionService);
                }
            }
        }
        return this.evaluationContext;
    }

    @Nullable
    protected <T> T evaluateExpression(Expression expression, Message<?> message, @Nullable Class<T> expectedType) {
        try {
            return evaluateExpression(expression, (Object) message, expectedType);
        } catch (Exception ex) {
            this.logger.debug("SpEL Expression evaluation failed with Exception.", ex);
            Throwable cause = null;
            if (ex instanceof EvaluationException) { // NOSONAR
                cause = ex.getCause();
            }
            throw IntegrationUtils.wrapInHandlingExceptionIfNecessary(message,
                    () -> "Expression evaluation failed: " + expression.getExpressionString(),
                    cause == null ? ex : cause);
        }
    }

    @Nullable
    protected Object evaluateExpression(String expression, Object input) {
        return evaluateExpression(expression, input, null);
    }

    @Nullable
    protected <T> T evaluateExpression(String expression, Object input, @Nullable Class<T> expectedType) {
        return EXPRESSION_PARSER.parseExpression(expression).getValue(getEvaluationContext(), input, expectedType);
    }

    @Nullable
    protected Object evaluateExpression(Expression expression, Object input) {
        return evaluateExpression(expression, input, null);
    }

    @Nullable
    protected <T> T evaluateExpression(Expression expression, @Nullable Class<T> expectedType) {
        return expression.getValue(getEvaluationContext(), expectedType);
    }

    @Nullable
    protected Object evaluateExpression(Expression expression) {
        return expression.getValue(getEvaluationContext());
    }

    @Nullable
    protected <T> T evaluateExpression(Expression expression, Object input, @Nullable Class<T> expectedType) {
        return expression.getValue(getEvaluationContext(), input, expectedType);
    }

    protected void onInit() {

    }

}