/*
 * Copyright 2002-2017 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.beans.factory.config;

import org.springframework.lang.Nullable;
import org.springframework.util.StringValueResolver;

StringValueResolver adapter for resolving placeholders and expressions against a ConfigurableBeanFactory. 
Note that this adapter resolves expressions as well, in contrast to the ConfigurableBeanFactory.resolveEmbeddedValue method. The BeanExpressionContext used is for the plain bean factory, with no scope specified for any contextual objects to access. 
Author:
Juergen Hoeller
See Also:
ConfigurableBeanFactory.resolveEmbeddedValue(String)
ConfigurableBeanFactory.getBeanExpressionResolver()
BeanExpressionContext
Since:
4.3/**
 * {@link StringValueResolver} adapter for resolving placeholders and
 * expressions against a {@link ConfigurableBeanFactory}.
 *
 * <p>Note that this adapter resolves expressions as well, in contrast
 * to the {@link ConfigurableBeanFactory#resolveEmbeddedValue} method.
 * The {@link BeanExpressionContext} used is for the plain bean factory,
 * with no scope specified for any contextual objects to access.
 *
 * @author Juergen Hoeller
 * @since 4.3
 * @see ConfigurableBeanFactory#resolveEmbeddedValue(String)
 * @see ConfigurableBeanFactory#getBeanExpressionResolver()
 * @see BeanExpressionContext
 */
public class EmbeddedValueResolver implements StringValueResolver {

	private final BeanExpressionContext exprContext;

	@Nullable
	private final BeanExpressionResolver exprResolver;


	public EmbeddedValueResolver(ConfigurableBeanFactory beanFactory) {
		this.exprContext = new BeanExpressionContext(beanFactory, null);
		this.exprResolver = beanFactory.getBeanExpressionResolver();
	}


	@Override
	@Nullable
	public String resolveStringValue(String strVal) {
		String value = this.exprContext.getBeanFactory().resolveEmbeddedValue(strVal);
		if (this.exprResolver != null && value != null) {
			Object evaluated = this.exprResolver.evaluate(value, this.exprContext);
			value = (evaluated != null ? evaluated.toString() : null);
		}
		return value;
	}

}