Spring 使用@ControllerAdvice 處理異常

Question

我創建了一個APIExceptionHandler class 來處理自定義運行時異常。 我創建的異常類之一是PasswordMismatchException 。 因此，每當遇到異常時，我都會返回APIResponse類型的響應。

現在我的問題是為什么使用CompletableFuture時沒有生成預期的響應。

APIResponse.java

@AllArgsConstructor
@Getter
@Setter
public class APIResponse {
    private Map<String, String> response;
}

異常處理程序（CompletableFuture）

    @ExceptionHandler(PasswordMismatchException.class)
    public CompletionStage<ResponseEntity<APIResponse>> passwordMismatchExceptionHandler(PasswordMismatchException exception) {
        return CompletableFuture.completedFuture(Collections.singletonMap(MESSAGE_FIELD, exception.getMessage()))
                .thenApply(APIResponse::new)
                .thenApply(response -> new ResponseEntity<>(response, HttpStatus.BAD_REQUEST));
    }

響應（與預期不同）

{
    "done": true,
    "cancelled": false,
    "completedExceptionally": false,
    "numberOfDependents": 0
}

異常處理程序（正常）

    @ExceptionHandler(PasswordMismatchException.class)
    public ResponseEntity<APIResponse> passwordMismatchExceptionHandler(PasswordMismatchException exception) {
        Map<String, String> errorMessageMap = Collections.singletonMap(MESSAGE_FIELD, exception.getMessage());
        APIResponse response = new APIResponse(errorMessageMap);
        return new ResponseEntity<>(response, HttpStatus.BAD_REQUEST);
    }

響應（如預期）

{
    "response": {
        "message": "Password did not match with Repeated Password."
    }
}

Answer 1

In spring boot the ObjectMapper by default used the getters and setters for Serialization and Deserialization , while the response type is CompletionStage the object mapper will be serializing corresponding child object (for example CompletableFuture ) and serializing method starts with get and is

public boolean isDone()
public boolean isCancelled()
public boolean isCompletedExceptionally()
public int getNumberOfDependents()

從那時起，方法的名稱是get ，它返回最終的 object， objectmapper只是忽略它

public T get() throws InterruptedException, ExecutionException