Spring WebFlux Adapter Support "BEST_MATCHING_PATTERN_ATTRIBUTE"

[icodening]

Describe what this PR does / why we need it

Spring WebFlux下使用Sentinel，支持将Path参数的路径视为同一资源。
如在 /users/{id} 下，/users/1、/users/2将被视为同一个资源 "/users/{id}"

Does this pull request fix one issue?

Fixes #2627

Describe how you did it

在SentinelWebFluxFilter中获取path动作之前加入获取"BEST_MATCHING_PATTERN_ATTRIBUTE"的埋点，如果埋点获取的结果为空，则使用默认的获取资源名逻辑

Describe how to verify it

需要使用新的方式装配 SentinelWebFluxFilter，方式如下

/**
 * best matching pattern extractor for RouterFunctionMapping
 */
@Bean
public HandlerMappingBestMatchingPatternExtractor routerFunctionBestMatchingPatternExtractor() {
    return new RouterFunctionMappingBestMatchingPatternExtractor();
}

/**
 * best matching pattern extractor for RequestMappingHandlerMapping
 */
@Bean
public HandlerMappingBestMatchingPatternExtractor requestMappingHandlerMappingBestMatchingExtractor() {
    return new RequestMappingHandlerMappingBestMatchingPatternExtractor();
}

@Bean
public SentinelWebFluxFilter sentinelWebFluxFilter(List<HandlerMapping> handlerMappings,
                                                   List<HandlerMappingBestMatchingPatternExtractor> handlerMappingBestMatchingExtractors) {
    return new SentinelWebFluxFilter(new DefaultBestMatchingPatternExtractor(handlerMappings, handlerMappingBestMatchingExtractors));
}

Special notes for reviews

下图为大致流程图可帮助理解

其中，HandlerMappingBestMatchingPatternExtractor接口有两个默认实现分别为RequestMappingHandlerMappingBestMatchingPatternExtractor, RouterFunctionMappingBestMatchingPatternExtractor. 两个提取器分别处理RequestMappingHandlerMapping与RouterFunctionMapping

[sczyh30]

Could you please add test cases for this feature?

[icodening]

Could you please add test cases for this feature?

OK,I will add test case soon

[icodening]

Could you please add test cases for this feature?

I have added test code, please review

[Hodor125]

Why is this feature not merged, is there any problem?

[wuwen5]

能否不修改SentinelWebFluxFilter，而通过WebFluxCallbackManager.setUrlCleaner 来插入实现。

我们是否可以类似这样

BiFunction<ServerWebExchange, String, String>  cleaner = (exchange, originUrl)-> {

          for (HandlerMapping handlerMapping : handlerMappings) {
              for (HandlerMappingBestMatchingPatternExtractor handlerMappingBestMatchingPatternExtractor : handlerMappingBestMatchingPatternExtractors) {
                  if (!handlerMappingBestMatchingPatternExtractor.supportExtract(handlerMapping)) {
                      continue;
                  }
                  String bestMatchingPath = handlerMappingBestMatchingPatternExtractor.extract(handlerMapping, exchange);
                  if (bestMatchingPath != null) {
                      return bestMatchingPath;
                  }
              }
          }
          
          PathPattern pathPattern = exchange.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
          if (pathPattern != null && pathPattern.matches(exchange.getRequest().getPath().pathWithinApplication())) {
              return pathPattern.getPatternString();
          }
          return originUrl;
      };

      WebFluxCallbackManager.setUrlCleaner(cleaner);

[wuwen5]

这里是否缺少了一个 @Override?