SpringBoot系列：用配置影响Bean加载 @ConditionalOnProperty
package org.springframework.boot.autoconfigure.condition;
...
@Order(Ordered.HIGHEST_PRECEDENCE + 40)
class OnPropertyCondition extends SpringBootCondition {
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
// 通过获类原始数据上的ConditionalOnProperty注解的参数值
List<AnnotationAttributes> allAnnotationAttributes = annotationAttributesFromMultiValueMap(
metadata.getAllAnnotationAttributes(ConditionalOnProperty.class.getName()));
List<ConditionMessage> noMatch = new ArrayList<>();
List<ConditionMessage> match = new ArrayList<>();
for (AnnotationAttributes annotationAttributes : allAnnotationAttributes) {
// 通过属性值，逐一判断配置信息中的信息是否满足 ， () 能获取到所有的配置信息
ConditionOutcome outcome = determineOutcome(annotationAttributes, context.getEnvironment());
(outcome.isMatch() ? match : noMatch).add(outcome.getConditionMessage());
}
if (!noMatch.isEmpty()) {
return ConditionOutcome.noMatch(ConditionMessage.of(noMatch));
}
return ConditionOutcome.match(ConditionMessage.of(match));
}
private List<AnnotationAttributes> annotationAttributesFromMultiValueMap(
MultiValueMap<String, Object> multiValueMap) {
...
return annotationAttributes;
}
private ConditionOutcome determineOutcome(AnnotationAttributes annotationAttributes, PropertyResolver resolver) {
Spec spec = new Spec(annotationAttributes);
List<String> missingProperties = new ArrayList<>();
List<String> nonMatchingProperties = new ArrayList<>();
// 通过属性值，判断配置信息中的信息是否满足
spec.collectProperties(resolver, missingProperties, nonMatchingProperties);
if (!missingProperties.isEmpty()) {
return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnProperty.class, spec)
.didNotFind("property", "properties").items(Style.QUOTE, missingProperties));
}
if (!nonMatchingProperties.isEmpty()) {
return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnProperty.class, spec)
.found("different value in property", "different value in properties")
.items(Style.QUOTE, nonMatchingProperties));
}
return ConditionOutcome
.match(ConditionMessage.forCondition(ConditionalOnProperty.class, spec).because("matched"));
}
private static class Spec {
private final String prefix;
private final String havingValue;
private final String[] names;
private final boolean matchIfMissing;
Spec(AnnotationAttributes annotationAttributes) {
...
}
private String[] getNames(Map<String, Object> annotationAttributes) {
...
}
private void collectProperties(PropertyResolver resolver, List<String> missing, List<String> nonMatching) {
for (String name : this.names) {
String key = this.prefix + name;
if (resolver.containsProperty(key)) {
// havingValue 默认为 ""
if (!isMatch(resolver.getProperty(key), this.havingValue)) {
nonMatching.add(name);
}
}
else {
if (!this.matchIfMissing) {
missing.add(name);
}
}
}
}
private boolean isMatch(String value, String requiredValue) {
if (StringUtils.hasLength(requiredValue)) {
return requiredValue.equalsIgnoreCase(value);
}
// havingValue 默认为 "" ，因此只要对应的属性不为false，在注解中没填havingValue的情况下，都是会match上conditon，即都会被加载
return !"false".equalsIgnoreCase(value);
}
@Override
public String toString() {
...
}
}
}