wuyouzhuguli/SpringAll · error · UserNotExistException

user not exist

Error message

user not exist

What it means

UserNotExistException is a project-defined RuntimeException (cc.mrbird.exception.UserNotExistException) whose super message is hardcoded to "user not exist" and which carries the offending id separately. UserController.get() throws it UNCONDITIONALLY for every GET /user/{id} where id matches \\d+. This is demo code for Spring MVC's @ControllerAdvice / @ExceptionHandler global exception handling, not real lookup logic.

Source

Thrown at 25.Spring-Boot-Exception/src/main/java/cc/mrbird/controller/UserController.java:15

package cc.mrbird.controller;

import cc.mrbird.exception.UserNotExistException;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("user")
public class UserController {

    @GetMapping("/{id:\\d+}")
    public void get(@PathVariable String id) {
        throw new UserNotExistException(id);
    }
}

View on GitHub (pinned to 614d2578d9)

Solutions

1. Register a @ControllerAdvice with @ExceptionHandler(UserNotExistException.class) returning a structured error body and HTTP status (e.g., 400 or 404).
2. Replace the unconditional throw with a real lookup (userService.findById(id)) and throw only when the result is null.
3. If this is throwaway demo code, remove the endpoint before shipping.
4. Verify the exception's message/id fields are what your handler serializes to the client.

Example fix

// before
@GetMapping("/{id:\\d+}")
public void get(@PathVariable String id) {
    throw new UserNotExistException(id);
}

// after
@GetMapping("/{id:\\d+}")
public User get(@PathVariable String id) {
    User user = userService.findById(id);
    if (user == null) {
        throw new UserNotExistException(id);
    }
    return user;
}

// Register once via @ControllerAdvice
@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(UserNotExistException.class)
    public ResponseEntity<Map<String, Object>> handle(UserNotExistException e) {
        Map<String, Object> body = new HashMap<>();
        body.put("id", e.getId());
        body.put("message", e.getMessage());
        return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(body);
    }
}

When it happens

Trigger: Any HTTP GET to /user/1, /user/42, etc. (path variable constrained to digits). The method always throws regardless of whether such a user exists.

Common situations: Developer left the demo throw in place expecting real service code; an @ExceptionHandler(UserNotExistException.class) is missing so Spring returns a default 500; the unconditional throw masks a missing findById call; tests hit the endpoint and see the literal message.

Related errors

• 服务异常

AI-assisted analysis of wuyouzhuguli/SpringAll@614d2578d9 (2026-08-14). Data as JSON: /api/errors/c610a6623bfc3a29. Report an issue: GitHub.