Spring | 如何在项目中优雅的处理异常 - 全局异常处理以及自定义异常处理

public void readFile() {
    try {
        FileInputStream fileInputStream = new FileInputStream("nonexistent.file");
    } catch (FileNotFoundException e) {
        e.printStackTrace(); // 或者进行其他的异常处理，如记录日志、抛出新的异常等。
    }
}
// 或者
public void readFile() throws FileNotFoundException {
    FileInputStream fileInputStream = new FileInputStream("nonexistent.file");
}

public void calculateLength() {
    String str = null;
    try {
        int length = str.length(); // 这会抛出NullPointerException
    } catch (NullPointerException e) {
        e.printStackTrace(); // 或者进行其他的异常处理，如记录日志、抛出新的异常等。
    }
}

@RestController
public class MyController {

    @GetMapping("/endpoint")
    public String endPoint() throws Exception {
        throw new Exception("异常出错！");
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<String> handleMyException(Exception e) {
        return new ResponseEntity<>(e.getMessage(), HttpStatus.BAD_REQUEST);
    }
}

@ControllerAdvice
public class GlobalExceptionHandler {
    
    @ExceptionHandler(MyException.class)
    public ResponseEntity<String> handleMyException(MyException e) {
        return new ResponseEntity<>(e.getMessage(), HttpStatus.BAD_REQUEST);
    }
}

@RestControllerAdvice
public class CustomResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {

    @Override
    protected ResponseEntity<Object> handleMethodArgumentNotValid(
            MethodArgumentNotValidException ex,
            HttpHeaders headers,
            HttpStatusCode status,
            WebRequest request){

        // 获取所有的错误信息
        List<String> errorDetails = ex.getBindingResult()
                                      .getFieldErrors()
                                      .stream()
                                      .map(fieldError -> fieldError.getField() + ": " + fieldError.getDefaultMessage())
                                      .collect(Collectors.toList());

        // 创建一个错误响应体对象
        ApiError apiError = new ApiError(
            LocalDateTime.now(),
            HttpStatus.BAD_REQUEST,
            "Validation Failed",
            errorDetails
        );

        // 返回定制的错误响应体
        return new ResponseEntity<>(apiError, HttpStatus.BAD_REQUEST);
    }
}

    @PostMapping("/user")
    public ResponseEntity<String> createUser(@Valid @RequestBody User user) {
        return new ResponseEntity<>("User created successfully!" + user.toString(), HttpStatus.CREATED);
    }

    /**
     * 参数校验
     * {@link MyController#createUser}
     */
    @Test
    void shouldReturnBadRequestWhenNameIsBlank() throws Exception {
        String userJson = "{\"name\":\"\"}"; // 空的name应该触发验证失败

        mockMvc.perform(post("/user")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content(userJson))
                .andExpect(status().isBadRequest());
    }

@RestController
public class CustomErrorController implements ErrorController {

    @RequestMapping("/error")
    public ResponseEntity<Map<String, Object>> handleError() {
        // Customize the error response
        return new ResponseEntity<>(...);
    }
    
    @Override
    public String getErrorPath() {
        return "/error";
    }
}

public class CustomException extends RuntimeException {
    public CustomException(String message) {
        super(message);
    }
}

@ControllerAdvice
public class CustomExceptionHandler {
    @ExceptionHandler(CustomException.class)
    public ResponseEntity<String> handleCustomException(CustomException e) {
        return new ResponseEntity<>(e.getMessage(), HttpStatus.BAD_REQUEST);
    }
}

public class ErrorResponse {
    private int status;
    private String message;
    private long timestamp;
    
    // Constructors, getters and setters
}

@ControllerAdvice
public class CustomExceptionHandler {
    
    @ExceptionHandler(CustomException.class)
    public ResponseEntity<ErrorResponse> handleCustomException(CustomException e) {
        ErrorResponse errorResponse = new ErrorResponse(HttpStatus.BAD_REQUEST.value(), e.getMessage(), System.currentTimeMillis());
        return new ResponseEntity<>(errorResponse, HttpStatus.BAD_REQUEST);
    }
}

@RestController
public class MyController {

    @GetMapping("/myEndpoint")
    public ResponseEntity<String> myEndpoint() {
        // ...
        return new ResponseEntity<>("Error Message", HttpStatus.BAD_REQUEST);
    }
}

@ResponseStatus(value = HttpStatus.NOT_FOUND, reason = "Resource not found")
public class ResourceNotFoundException extends RuntimeException {
}

@RestController
public class MyController {

    @GetMapping("/myEndpoint")
    public String myEndpoint() {
        // ...
        throw new ResourceNotFoundException();
    }
    
    @ExceptionHandler(ResourceNotFoundException.class)
    @ResponseStatus(HttpStatus.NOT_FOUND)
    public String handleResourceNotFoundException() {
        return "Resource not found";
    }
}

if (userInput == null) {
    throw new IllegalArgumentException("User input cannot be null");
}

public class UserNotFoundException extends RuntimeException {
    public UserNotFoundException(String userId) {
        super("User with ID " + userId + " not found");
    }
}

throw new UserNotFoundException(userId);

logger.error("Exception occurred", exception);

return ResponseEntity.status(HttpStatus.BAD_REQUEST).body("Invalid user input");

logger.error("User not found: {}", userId, exception);

@Test
void shouldThrowUserNotFoundException() {
    Assertions.assertThrows(UserNotFoundException.class, () -> {
        userService.findUser("invalidId");
    });
}