org.springframework.context.annotation.ConfigurationCondition集成了org.springframework.context.annotation.Condition接口。Condition主要是用来带条件的自动装配的。
请问ConfigurationCondition接口是干啥的？
官方的接口申明如下：
package org.springframework.context.annotation;
/**
* A {@link Condition} that offers more fine-grained control when used with
* {@code @Configuration}. Allows certain {@link Condition}s to adapt when they match
* based on the configuration phase. For example, a condition that checks if a bean
* has already been registered might choose to only be evaluated during the
* {@link ConfigurationPhase#REGISTER_BEAN REGISTER_BEAN} {@link ConfigurationPhase}.
*
* @author Phillip Webb
* @since 4.0
* @see Configuration
*/
public interface ConfigurationCondition extends Condition {
/**
* Return the {@link ConfigurationPhase} in which the condition should be evaluated.
*/
ConfigurationPhase getConfigurationPhase();
/**
* The various configuration phases where the condition could be evaluated.
*/
public static enum ConfigurationPhase {
/**
* The {@link Condition} should be evaluated as a {@code @Configuration}
* class is being parsed.
* <p>If the condition does not match at this point, the {@code @Configuration}
* class will not be added.
*/
PARSE_CONFIGURATION,
/**
* The {@link Condition} should be evaluated when adding a regular
* (non {@code @Configuration}) bean. The condition will not prevent
* {@code @Configuration} classes from being added.
* <p>At the time that the condition is evaluated, all {@code @Configuration}s
* will have been parsed.
*/
REGISTER_BEAN
}
}Condition可以用于判断只有当某个Bean已注册的情况下才进行Configuration，大部分情况下直接用Condition就OK了。ConfigurationCondition只是在Condition上面加了一个东西，就是什么时候做这个判断，也就是代码里的PARSE_CONFIGURATION和REGISTER_BEAN，具体啥意思参加这两个枚举的注释了