public String getKey(final String selectorId, final String ruleId) {
        return String.join("_", selectorId, ruleId);
    }
Gets key.

@param selectorId the selector id
@param ruleId the rule id
@return the key
shenyu-plugin/shenyu-plugin-base/src/main/java/org/apache/shenyu/plugin/base/utils/CacheKeyUtils.java