fallback顧名思義當Java程序運行發生錯誤時，由該參數定義的方法進行處理

@GetMapping(value = "/consumer/{id}")@SentinelResource(value = "consumer", fallback = "handlerFallback")public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {ResponseEntity<String> entity = remoteService.getData(id);if (id <= 0) {throw new IllegalArgumentException("非法參數異常!");} else if (entity.getData() == null) {throw new NullPointerException("無響應數據，空指針異常!");}return entity;}public ResponseEntity<String> handlerFallback(Integer id, Throwable e) {return new ResponseEntity<>(443, "程序處理異常，開始執行fallback數據-->" +e.getMessage());}

blockHandler這個也很好明白，也就是當API違背控制臺設置的閾值時，執行該參數定義的方法進行處理；說白了就是限流之后的處理

@GetMapping(value = "/consumer/{id}")@SentinelResource(value = "consumer",blockHandler = "blockHandler")public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {ResponseEntity<String> entity = remoteService.getData(id);if (id <= 0) {throw new IllegalArgumentException("非法參數異常!");} else if (entity.getData() == null) {throw new NullPointerException("無響應數據，空指針異常!");}return entity;}public ResponseEntity<String> blockHandler(BlockException blockException) {return new ResponseEntity<>(444, "QPS過高，服務開始熔斷降級--->"+blockException.getMessage());}

那么問題來了，如果同時發生Java運行錯誤和限流，那么會走哪個默認的方法呢？

@GetMapping(value = "/consumer/{id}")@SentinelResource(value = "consumer", fallback = "handlerFallback", blockHandler = "blockHandler")public ResponseEntity<String> consumerData(@PathVariable("id")Integer id) {ResponseEntity<String> entity = remoteService.getData(id);if (id <= 0) {throw new IllegalArgumentException("非法參數異常!");} else if (entity.getData() == null) {throw new NullPointerException("無響應數據，空指針異常!");}return entity;}public ResponseEntity<String> handlerFallback(Integer id, Throwable e) {return new ResponseEntity<>(443, "程序處理異常，開始執行fallback數據-->" +e.getMessage());}public ResponseEntity<String> blockHandler(Integer id, BlockException blockException) {return new ResponseEntity<>(444, "QPS過高，服務開始熔斷降級--->"+blockException.getMessage());}

設置限流規則

當我持續刷新，它走的是blockHandler路線

記得在配置文件加入以下

feign:sentinel:enabled: true

總結

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