/*
* Copyright 2018-2020 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.
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package org.springframework.data.util;
import lombok.experimental.UtilityClass;
import java.util.Map;
import javax.annotation.Nullable;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
import org.springframework.util.Assert;
Simple helper to allow lenient lookup of beans of a given type from a ListableBeanFactory
. This is not user facing API but a mere helper for Spring Data configuration code. Author: Oliver Gierke Since: 2.1 @soundtrack Dave Matthews Band - Bartender (DMB Live 25)
/**
* Simple helper to allow lenient lookup of beans of a given type from a {@link ListableBeanFactory}. This is not user
* facing API but a mere helper for Spring Data configuration code.
*
* @author Oliver Gierke
* @since 2.1
* @soundtrack Dave Matthews Band - Bartender (DMB Live 25)
*/
@UtilityClass
public class BeanLookup {
Returns a Lazy
for the unique bean of the given type from the given BeanFactory
(which needs to be a ListableBeanFactory
). The lookup will produce a NoUniqueBeanDefinitionException
in case multiple beans of the given type are available in the given BeanFactory
. Params: - type – must not be null.
- beanFactory – the
BeanFactory
to lookup the bean from.
Returns: a Lazy
for the unique bean of the given type or the instance provided by the fallback in case no bean of the given type can be found.
/**
* Returns a {@link Lazy} for the unique bean of the given type from the given {@link BeanFactory} (which needs to be
* a {@link ListableBeanFactory}). The lookup will produce a {@link NoUniqueBeanDefinitionException} in case multiple
* beans of the given type are available in the given {@link BeanFactory}.
*
* @param type must not be {@literal null}.
* @param beanFactory the {@link BeanFactory} to lookup the bean from.
* @return a {@link Lazy} for the unique bean of the given type or the instance provided by the fallback in case no
* bean of the given type can be found.
*/
public static <T> Lazy<T> lazyIfAvailable(Class<T> type, BeanFactory beanFactory) {
Assert.notNull(type, "Type must not be null!");
Assert.isInstanceOf(ListableBeanFactory.class, beanFactory);
return Lazy.of(() -> lookupBean(type, (ListableBeanFactory) beanFactory));
}
Looks up the unique bean of the given type from the given ListableBeanFactory
. Params: - type – must not be null.
- beanFactory – must not be null.
Returns:
/**
* Looks up the unique bean of the given type from the given {@link ListableBeanFactory}.
*
* @param type must not be {@literal null}.
* @param beanFactory must not be {@literal null}.
* @return
*/
@Nullable
private static <T> T lookupBean(Class<T> type, ListableBeanFactory beanFactory) {
Map<String, T> names = beanFactory.getBeansOfType(type, false, false);
switch (names.size()) {
case 0:
return null;
case 1:
return names.values().iterator().next();
default:
throw new NoUniqueBeanDefinitionException(type, names.keySet());
}
}
}