lodsve.core.condition.OnExpressionCondition.java Source code

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Here is the source code for lodsve.core.condition.OnExpressionCondition.java

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/*
 * Copyright 2012-2013 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 lodsve.core.condition;

import org.springframework.beans.factory.config.BeanExpressionContext;
import org.springframework.beans.factory.config.BeanExpressionResolver;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.expression.StandardBeanExpressionResolver;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.core.type.ClassMetadata;

/**
 * A Condition that evaluates a SpEL expression.
 *
 * @author Dave Syer
 * @see ConditionalOnExpression
 */
@Order(Ordered.LOWEST_PRECEDENCE - 20)
class OnExpressionCondition extends SpringBootCondition {

    @Override
    public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {

        String expression = (String) metadata.getAnnotationAttributes(ConditionalOnExpression.class.getName())
                .get("value");
        String rawExpression = expression;
        if (!expression.startsWith("#{")) {
            // For convenience allow user to provide bare expression with no #{} wrapper
            expression = "#{" + expression + "}";
        }

        // Explicitly allow environment placeholders inside the expression
        expression = context.getEnvironment().resolvePlaceholders(expression);
        ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
        BeanExpressionResolver resolver = (beanFactory != null) ? beanFactory.getBeanExpressionResolver() : null;
        BeanExpressionContext expressionContext = (beanFactory != null)
                ? new BeanExpressionContext(beanFactory, null)
                : null;
        if (resolver == null) {
            resolver = new StandardBeanExpressionResolver();
        }
        boolean result = (Boolean) resolver.evaluate(expression, expressionContext);

        StringBuilder message = new StringBuilder("SpEL expression");
        if (metadata instanceof ClassMetadata) {
            message.append(" on " + ((ClassMetadata) metadata).getClassName());
        }
        message.append(": " + rawExpression);
        return new ConditionOutcome(result, message.toString());
    }

}