org.springframework.boot.autoconfigure.condition.OnExpressionCondition Maven / Gradle / Ivy
/*
* Copyright 2012-2019 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.boot.autoconfigure.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;
/**
* A Condition that evaluates a SpEL expression.
*
* @author Dave Syer
* @author Stephane Nicoll
* @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");
expression = wrapIfNecessary(expression);
ConditionMessage.Builder messageBuilder = ConditionMessage.forCondition(ConditionalOnExpression.class,
"(" + expression + ")");
expression = context.getEnvironment().resolvePlaceholders(expression);
ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
if (beanFactory != null) {
boolean result = evaluateExpression(beanFactory, expression);
return new ConditionOutcome(result, messageBuilder.resultedIn(result));
}
return ConditionOutcome.noMatch(messageBuilder.because("no BeanFactory available."));
}
private Boolean evaluateExpression(ConfigurableListableBeanFactory beanFactory, String expression) {
BeanExpressionResolver resolver = beanFactory.getBeanExpressionResolver();
if (resolver == null) {
resolver = new StandardBeanExpressionResolver();
}
BeanExpressionContext expressionContext = new BeanExpressionContext(beanFactory, null);
Object result = resolver.evaluate(expression, expressionContext);
return (result != null && (boolean) result);
}
/**
* Allow user to provide bare expression with no '#{}' wrapper.
* @param expression source expression
* @return wrapped expression
*/
private String wrapIfNecessary(String expression) {
if (!expression.startsWith("#{")) {
return "#{" + expression + "}";
}
return expression;
}
}