1. 多次校验文件是否存在

2. 恢复之前的校验顺序
3. 抽象通用逻辑

Author: PleaseGiveMeTheCoke

client/src/main/java/com/alibaba/nacos/client/config/impl/ClientWorker.java

@@ -870,34 +870,50 @@ public void checkLocalConfig(CacheData cacheData) {
             // Check if a failover file exists for the specified dataId, group, and tenant.
             File file = LocalConfigInfoProcessor.getFailoverFile(envName, dataId, group, tenant);
 
-            // not using local config info, but a failover file exists
-            boolean failOverFileCreated = !cacheData.isUseLocalConfigInfo() && file.exists();
-
-            // using local config info, but there is a change in local configuration
-            boolean failOverFileChanged = cacheData.isUseLocalConfigInfo() && file.exists() && cacheData.getLocalConfigInfoVersion() != file.lastModified();
-
-            // using local config info, but the failover file is deleted
-            boolean failOverFileDeleted = cacheData.isUseLocalConfigInfo() && !file.exists();
-
-            if (failOverFileCreated || failOverFileChanged) {
-                // load and use the file content
-                String content = LocalConfigInfoProcessor.getFailover(envName, dataId, group, tenant);
-                final String md5 = MD5Utils.md5Hex(content, Constants.ENCODE);
-                cacheData.setUseLocalConfigInfo(true);
-                cacheData.setLocalConfigInfoVersion(file.lastModified());
-                cacheData.setContent(content);
-                LOGGER.warn(
-                        "[{}] [failover-change] failover file {}. dataId={}, group={}, tenant={}, md5={}, content={}",
-                        failOverFileCreated ? "created" : "changed", envName, dataId, group, tenant, md5, ContentUtils.truncateContent(content));
+            if (isFailOverFileCreated(cacheData, file)) {
+                loadAndUse(cacheData, file, true);
+                return;
             }
 
-            if (failOverFileDeleted) {
+            if (isFailOverFileDeleted(cacheData, file)) {
                 // switch back to server config.
                 cacheData.setUseLocalConfigInfo(false);
                 LOGGER.warn("[{}] [failover-change] failover file deleted. dataId={}, group={}, tenant={}", envName,
                         dataId, group, tenant);
+                return;
+            }
+
+            if (isFailOverFileChanged(cacheData, file)) {
+                loadAndUse(cacheData, file, false);
             }
         }
+
+        private void loadAndUse(CacheData cacheData, File file, boolean failOverFileCreated) {
+            String content = LocalConfigInfoProcessor.getFailover(cacheData.envName, cacheData.dataId, cacheData.group, tenant);
+            final String md5 = MD5Utils.md5Hex(content, Constants.ENCODE);
+            cacheData.setUseLocalConfigInfo(true);
+            cacheData.setLocalConfigInfoVersion(file.lastModified());
+            cacheData.setContent(content);
+            LOGGER.warn(
+                    "[{}] [failover-change] failover file {}. dataId={}, group={}, tenant={}, md5={}, content={}",
+                    failOverFileCreated ? "created" : "changed",
+                    cacheData.envName, cacheData.dataId, cacheData.group, tenant, md5, ContentUtils.truncateContent(content));
+        }
+
+        private boolean isFailOverFileCreated(CacheData cacheData, File file) {
+            // not using local config info, but a failover file exists
+            return !cacheData.isUseLocalConfigInfo() && file.exists();
+        }
+
+        private boolean isFailOverFileChanged(CacheData cacheData, File file) {
+            // using local config info, but there is a change in local configuration
+            return cacheData.isUseLocalConfigInfo() && file.exists() && cacheData.getLocalConfigInfoVersion() != file.lastModified();
+        }
+
+        private boolean isFailOverFileDeleted(CacheData cacheData, File file) {
+            // using local config info, but the failover file is deleted
+            return cacheData.isUseLocalConfigInfo() && !file.exists();
+        }
 
         private ExecutorService ensureSyncExecutor(String taskId) {
             if (!multiTaskExecutor.containsKey(taskId)) {