如何处理lambda表达式中的异常[重复]

Question

我有metohod myservice#create，它抛出CustomException。我在可选#map中调用此方法，如下所示：

return Optional.ofNullable(obj)
        .map(optObj -> {
            try {
                return myService.create(optObj);
            } catch (CustomException e) {
                return new ResponseEntity<>(e.getMessage(), HttpStatus.BAD_REQUEST);
            }
        })
        .map(created -> new ResponseEntity<>("Operation successful", HttpStatus.CREATED))
        .orElse(new ResponseEntity<>("Operation failed", HttpStatus.BAD_REQUEST));

当我用引起异常的参数调用这个方法时，就会捕获CustomException，但结果是操作成功，状态为200。如何在lambda中处理此异常并返回异常消息？

Answer 1

您确实捕获了异常并返回新的ResponseEntity<>(E.getMessage(),HttpStatus.BAD_Request)。

然后将其映射到new responseEntity<>（“operation successful”,HttpStatus.created)。

如果您希望只有在调用成功的情况下才有新的ResponseEntity<>（“操作成功”，HttpStatus.Created)重写代码到：

return Optional.ofNullable(obj)
        .map(optObj -> {
            try {
                myService.create(optObj);
                return new ResponseEntity<>("Operation successful", HttpStatus.CREATED);
            } catch (CustomException e) {
                return new ResponseEntity<>(e.getMessage(), HttpStatus.BAD_REQUEST);
            }
        })
        .orElse(new ResponseEntity<>("Operation failed", HttpStatus.BAD_REQUEST));