org.springframework.boot.autoconfigure.condition.ConditionalOnProperty 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 java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Conditional;
import org.springframework.core.env.Environment;
/**
* {@link Conditional @Conditional} that checks if the specified properties have a
* specific value. By default the properties must be present in the {@link Environment}
* and not equal to {@code false}. The {@link #havingValue()} and
* {@link #matchIfMissing()} attributes allow further customizations.
*
* The {@link #havingValue} attribute can be used to specify the value that the property
* should have. The table below shows when a condition matches according to the property
* value and the {@link #havingValue()} attribute:
*
*
* Having values
*
* Property Value
* {@code havingValue=""}
* {@code havingValue="true"}
* {@code havingValue="false"}
* {@code havingValue="foo"}
*
*
* {@code "true"}
* yes
* yes
* no
* no
*
*
* {@code "false"}
* no
* no
* yes
* no
*
*
* {@code "foo"}
* yes
* no
* no
* yes
*
*
*
* If the property is not contained in the {@link Environment} at all, the
* {@link #matchIfMissing()} attribute is consulted. By default missing attributes do not
* match.
*
* This condition cannot be reliably used for matching collection properties. For example,
* in the following configuration, the condition matches if {@code spring.example.values}
* is present in the {@link Environment} but does not match if
* {@code spring.example.values[0]} is present.
*
*
* @ConditionalOnProperty(prefix = "spring", name = "example.values")
* class ExampleAutoConfiguration {
* }
*
*
* It is better to use a custom condition for such cases.
*
* @author Maciej Walkowiak
* @author Stephane Nicoll
* @author Phillip Webb
* @since 1.1.0
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.TYPE, ElementType.METHOD })
@Documented
@Conditional(OnPropertyCondition.class)
public @interface ConditionalOnProperty {
/**
* Alias for {@link #name()}.
* @return the names
*/
String[] value() default {};
/**
* A prefix that should be applied to each property. The prefix automatically ends
* with a dot if not specified. A valid prefix is defined by one or more words
* separated with dots (e.g. {@code "acme.system.feature"}).
* @return the prefix
*/
String prefix() default "";
/**
* The name of the properties to test. If a prefix has been defined, it is applied to
* compute the full key of each property. For instance if the prefix is
* {@code app.config} and one value is {@code my-value}, the full key would be
* {@code app.config.my-value}
*
* Use the dashed notation to specify each property, that is all lower case with a "-"
* to separate words (e.g. {@code my-long-property}).
* @return the names
*/
String[] name() default {};
/**
* The string representation of the expected value for the properties. If not
* specified, the property must not be equal to {@code false}.
* @return the expected value
*/
String havingValue() default "";
/**
* Specify if the condition should match if the property is not set. Defaults to
* {@code false}.
* @return if should match if the property is missing
*/
boolean matchIfMissing() default false;
}