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/*
* Copyright 2014 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.yarn.support;
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.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
/**
* Base class providing common functionality for using Spring expression language.
*
* @author Mark Fisher
* @author Dave Syer
* @author Oleg Zhurakousky
* @author Artem Bilan
* @author Gary Russell
* @author Janne Valkealahti
*
*/
public abstract class AbstractExpressionEvaluator implements BeanFactoryAware, InitializingBean {
private volatile StandardEvaluationContext evaluationContext;
private final ExpressionParser expressionParser = new SpelExpressionParser();
private final BeanFactoryTypeConverter typeConverter = new BeanFactoryTypeConverter();
private volatile BeanFactory beanFactory;
@Override
public void setBeanFactory(final BeanFactory beanFactory) {
if (beanFactory != null) {
this.beanFactory = beanFactory;
this.typeConverter.setBeanFactory(beanFactory);
if (this.evaluationContext != null && this.evaluationContext.getBeanResolver() == null) {
this.evaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
}
}
}
@Override
public void afterPropertiesSet() throws Exception {
getEvaluationContext();
}
/**
* Sets the conversion service.
*
* @param conversionService the new conversion service
*/
public void setConversionService(ConversionService conversionService) {
if (conversionService != null) {
this.typeConverter.setConversionService(conversionService);
}
}
/**
* Gets the evaluation context.
*
* @return the evaluation context
*/
protected StandardEvaluationContext getEvaluationContext() {
return this.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);
}
if (this.typeConverter != null) {
this.evaluationContext.setTypeConverter(this.typeConverter);
}
}
return this.evaluationContext;
}
protected Object evaluateExpression(String expression, Object input) {
return this.evaluateExpression(expression, input, (Class) null);
}
protected T evaluateExpression(String expression, Object input, Class expectedType) {
return this.expressionParser.parseExpression(expression).getValue(this.getEvaluationContext(), input, expectedType);
}
protected Object evaluateExpression(Expression expression, Object input) {
return this.evaluateExpression(expression, input, (Class) null);
}
protected T evaluateExpression(Expression expression, Class expectedType) {
return expression.getValue(this.getEvaluationContext(), expectedType);
}
protected Object evaluateExpression(Expression expression) {
return expression.getValue(this.getEvaluationContext());
}
protected T evaluateExpression(Expression expression, Object input, Class expectedType) {
return expression.getValue(this.getEvaluationContext(), input, expectedType);
}
}