spring boot 源码解析36-ConditionalOnEnabledEndpoint

前言

本文我们来解析OnEnabledEndpointCondition的实现,这个还是很简单的.目的是为了做下缓冲,后面的内容比较复杂.好了,开始吧.

解析

@ConditionalOnEnabledEndpoint

代码如下:

@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.METHOD, ElementType.TYPE })
@Conditional(OnEnabledEndpointCondition.class)
@Documented
public @interface ConditionalOnEnabledEndpoint {

// endpoint的名字
String value();

// 返回endpoint是否可用,默认是可用的
boolean enabledByDefault() default true;

}

其处理类为OnEnabledEndpointCondition.

OnEnabledEndpointCondition

OnEnabledEndpointCondition 继承自SpringBootCondition.

getMatchOutcome 实现如下:

public ConditionOutcome getMatchOutcome(ConditionContext context,
AnnotatedTypeMetadata metadata) {
// 1. 获得@ConditionalOnEnabledEndpoint配置的Endpoint的名字和enabledByDefault的值
AnnotationAttributes annotationAttributes = AnnotationAttributes.fromMap(metadata
.getAnnotationAttributes(ConditionalOnEnabledEndpoint.class.getName()));
String endpointName = annotationAttributes.getString("value");
boolean enabledByDefault = annotationAttributes.getBoolean("enabledByDefault");
// 2. 获得endpoints.endpointName.enabled 的配置.然后进行返回,如此时传入的是env,则读取endpoints.env.enabled 的配置
ConditionOutcome outcome = determineEndpointOutcome(endpointName,
enabledByDefault, context);
if (outcome != null) {
return outcome;
}
// 3.读取endpoints.enabled的配置,如果没有配置的话,则默认匹配
return determineAllEndpointsOutcome(context);
}

获得@ConditionalOnEnabledEndpoint配置的Endpoint的名字和enabledByDefault的值

获得endpoints.endpointName.enabled 的配置.如果有配置的化则进行返回.如此时传入的是env,则读取endpoints.env.enabled 的配置.代码如下:

private ConditionOutcome determineEndpointOutcome(String endpointName,
boolean enabledByDefault, ConditionContext context) {
RelaxedPropertyResolver resolver = new RelaxedPropertyResolver(
context.getEnvironment(), "endpoints." + endpointName + ".");
if (resolver.containsProperty("enabled") || !enabledByDefault) {
boolean match = resolver.getProperty("enabled", Boolean.class,
enabledByDefault);
ConditionMessage message = ConditionMessage
.forCondition(ConditionalOnEnabledEndpoint.class,
"(" + endpointName + ")")
.because(match ? "enabled" : "disabled");
return new ConditionOutcome(match, message);
}
return null;
}

实例化RelaxedPropertyResolver,读取endpoints.endpointName. 开头的配置

如果配置有endpoints.endpointName.enabled 或者 默认该endpoint不默认生效

获得有endpoints.endpointName.enabled的值,构造ConditionOutcome,然后返回

返回null

读取endpoints.enabled的配置,如果没有配置的话,则默认匹配.代码如下:

private ConditionOutcome determineAllEndpointsOutcome(ConditionContext context) {
RelaxedPropertyResolver resolver = new RelaxedPropertyResolver(
context.getEnvironment(), "endpoints.");
boolean match = Boolean.valueOf(resolver.getProperty("enabled", "true"));
ConditionMessage message = ConditionMessage
.forCondition(ConditionalOnEnabledEndpoint.class)
.because("All endpoints are " + (match ? "enabled" : "disabled")
+ " by default");
return new ConditionOutcome(match, message);
}

实例化RelaxedPropertyResolver,读取endpoints. 开头的配置

获取endpoints.enabled 的配置,如果没有配置,则返回true

构造ConditionOutcome进行返回

使用案例:

在EndpointWebMvcManagementContextConfiguration中有如下方法:

@Bean
@ConditionalOnMissingBean
@ConditionalOnBean(EnvironmentEndpoint.class)
@ConditionalOnEnabledEndpoint("env")
public EnvironmentMvcEndpoint environmentMvcEndpoint(EnvironmentEndpoint delegate) {
return new EnvironmentMvcEndpoint(delegate);
}

其中使用到了@ConditionalOnEnabledEndpoint注解,意思是当配置有endpoints. env.enabled=true或者配置有endpoints.enabled=true或者没有配置endpoints.enabled,endpoints. env.enabled时默认生效