org.springframework.integration.jpa.support.parametersource.ExpressionEvaluatingParameterSourceFactory.java Source code

Introduction

Here is the source code for org.springframework.integration.jpa.support.parametersource.ExpressionEvaluatingParameterSourceFactory.java

Source

/*
 * Copyright 2002-2016 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.integration.jpa.support.parametersource;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
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.BeanFactory;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionException;
import org.springframework.integration.jpa.support.JpaParameter;
import org.springframework.integration.jpa.support.parametersource.ExpressionEvaluatingParameterSourceUtils.ParameterExpressionEvaluator;
import org.springframework.util.Assert;

/**
 * A SpEL expression based {@link ParameterSourceFactory} implementation.
 *
 * @author Gunnar Hillert
 * @author Gary Russell
 * @author Artem Bilan
 *
 * @since 2.2
 */
public class ExpressionEvaluatingParameterSourceFactory implements ParameterSourceFactory {

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

    private static final Object ERROR = new Object();

    private volatile List<JpaParameter> parameters;

    private final ParameterExpressionEvaluator expressionEvaluator = new ParameterExpressionEvaluator();

    public ExpressionEvaluatingParameterSourceFactory() {
        this(null);
    }

    public ExpressionEvaluatingParameterSourceFactory(BeanFactory beanFactory) {
        this.parameters = new ArrayList<>();
        this.expressionEvaluator.setBeanFactory(beanFactory);
    }

    /**
     * Define the (optional) parameter values.
     * @param parameters the parameters to be set
     */
    public void setParameters(List<JpaParameter> parameters) {

        Assert.notEmpty(parameters, "parameters must not be null or empty.");

        for (JpaParameter parameter : parameters) {
            Assert.notNull(parameter, "The provided list (parameters) cannot contain null values.");
        }

        this.parameters = parameters;
        this.expressionEvaluator.getEvaluationContext().setVariable("staticParameters",
                ExpressionEvaluatingParameterSourceUtils.convertStaticParameters(parameters));

    }

    public PositionSupportingParameterSource createParameterSource(final Object input) {
        return new ExpressionEvaluatingParameterSource(input, this.parameters, this.expressionEvaluator);
    }

    protected class ExpressionEvaluatingParameterSource implements PositionSupportingParameterSource {

        private final Object input;

        private volatile Map<String, Object> values = new HashMap<>();

        private final List<JpaParameter> parameters;

        private final Map<String, JpaParameter> parametersMap;

        private final ParameterExpressionEvaluator expressionEvaluator;

        protected ExpressionEvaluatingParameterSource(Object input, List<JpaParameter> parameters,
                ParameterExpressionEvaluator expressionEvaluator) {

            this.input = input;
            this.expressionEvaluator = expressionEvaluator;
            this.parameters = parameters;
            this.parametersMap = new HashMap<>(parameters.size());
            for (JpaParameter parameter : parameters) {
                this.parametersMap.put(parameter.getName(), parameter);
            }
            this.values.putAll(ExpressionEvaluatingParameterSourceUtils.convertStaticParameters(parameters));

        }

        public Object getValueByPosition(int position) {

            Assert.isTrue(position >= 0, "The position must be non-negative.");

            if (position <= this.parameters.size()) {

                final JpaParameter parameter = this.parameters.get(position);

                if (parameter.getValue() != null) {
                    return parameter.getValue();
                }

                if (parameter.getExpression() != null) {
                    Expression expression;

                    if (this.input instanceof Collection<?>) {
                        expression = parameter.getProjectionExpression();
                    } else {
                        expression = parameter.getSpelExpression();
                    }

                    final Object value = this.expressionEvaluator.evaluateExpression(expression, this.input);
                    if (parameter.getName() != null) {
                        this.values.put(parameter.getName(), value);
                    }
                    if (logger.isDebugEnabled()) {
                        logger.debug("Resolved expression " + expression + " to " + value);
                    }
                    return value;

                }

            }

            return null;

        }

        public Object getValue(String paramName) {
            if (this.values.containsKey(paramName)) {
                return this.values.get(paramName);
            }

            if (!this.parametersMap.containsKey(paramName)) {
                JpaParameter parameter = new JpaParameter(paramName, null, paramName);
                ExpressionEvaluatingParameterSourceFactory.this.parameters.add(parameter);
                this.parametersMap.put(paramName, parameter);
            }

            JpaParameter jpaParameter = this.parametersMap.get(paramName);

            Expression expression;

            if (this.input instanceof Collection<?>) {
                expression = jpaParameter.getProjectionExpression();
            } else {
                expression = jpaParameter.getSpelExpression();
            }

            final Object value = this.expressionEvaluator.evaluateExpression(expression, this.input);
            this.values.put(paramName, value);
            if (logger.isDebugEnabled()) {
                logger.debug("Resolved expression " + expression + " to " + value);
            }
            return value;
        }

        public boolean hasValue(String paramName) {
            try {
                final Object value = getValue(paramName);
                if (value == ERROR) {
                    return false;
                }
            } catch (ExpressionException e) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Could not evaluate expression", e);
                }
                this.values.put(paramName, ERROR);
                return false;
            }
            return true;
        }

    }

}