在Spring应用程序中处理异常的位置

Question

我还在学春天.我有一个应用程序设置,我正在尝试理解Spring中的异常处理.

我正在@ControllerAdvice用来处理异常.在我的应用程序有几层如Services,Controllers,Models和Repositories.我应该在哪个层处理异常？或者我应该在适当的时候处理每一层中的异常？

Answer 1

这是在Spring中启动异常处理的好方法:

步骤1 -创建特定的DefaultExceptionHandler类,并使用@ControllerAdvice批注对其进行批注.在此处理程序类中,您有不同的方法,捕获预期和意外的异常,这些异常使用@ExceptionHandler批注进行批注:

@ControllerAdvice("com.stackoverflow.example")
@SuppressWarnings("WeakerAccess")
public class DefaultExceptionHandler extends ResponseEntityExceptionHandler {

    private final Logger log = LoggerFactory.getLogger("DefaultExceptionHandler");

    private final MessageSourceAccessor messageSource;

    @Autowired
    public DefaultExceptionHandler(MessageSourceAccessor messageSource) {
        Assert.notNull(messageSource, "messageSource must not be null");
        this.messageSource = messageSource;
     }

      @ExceptionHandler(ApplicationSpecificException.class)
      public ResponseEntity<Object> handleApplicationSpecificException(ApplicationSpecificExceptionex) {
         final Error error = buildError(ex);
         return handleExceptionInternal(ex, ex.getHttpStatus(), error);
      }

       @ExceptionHandler(Exception.class)
       public ResponseEntity<Object> handleException(Exception ex) {
           final Error error = buildError(ex);
           return handleExceptionInternal(ex, HttpStatus.INTERNAL_SERVER_ERROR, error);
    }
}

第2步 -创建一个特定于应用程序的异常(ApplicationSpecificException类),用于预期的异常,并在任何级别抛出此异常,它将被Spring接收:

public class ApplicationSpecificException extends RuntimeException {

    private static final long serialVersionUID = 1L;

    private final ExceptionType exceptionType;

    public ApplicationSpecificException(ExceptionType exceptionType, Object... messageArguments) {
        super(MessageFormat.format(exceptionType.getMessage(), messageArguments));
        this.exceptionType = exceptionType;
    }

    public ApplicationSpecificException(ExceptionType exceptionType, final Throwable cause, Object... messageArguments) {
        super(MessageFormat.format(exceptionType.getMessage(), messageArguments), cause);
        this.exceptionType = exceptionType;
    }

    public HttpStatus getHttpStatus() {
        return exceptionType.getStatus();
    }

    public ExceptionType getExceptionType() {
        return exceptionType;
    }
}

ExceptionType是一个枚举:

public enum ExceptionType {

    HTTP_INTERNAL_SERVER_ERROR(HttpStatus.INTERNAL_SERVER_ERROR, "An internal server error occurred.");
    //you can specify your own exception types...

    private HttpStatus status;
    private String message;

    ExceptionType(HttpStatus status, String message) {
        this.status = status;
        this.message = message;
    }

    public HttpStatus getStatus() {
        return status;
    }

    public String getMessage() {
        return message;
    }
}

第3步 -最后,创建了一个ExceptionFactory类.这允许您在应用程序日志中自动记录异常:

public class ExceptionFactory {

    private static final Logger LOG = LoggerFactory.getLogger(ExceptionFactory.class);

    public static ApplicationSpecificException create(final Throwable cause, final ExceptionType exceptionType, final Object... messageArguments) {
        LOG.error(MessageFormat.format(exceptionType.getMessage(), messageArguments), cause);
        return new ApplicationSpecificException (exceptionType, cause, messageArguments);
    }

    public static ApplicationSpecificException create(final ExceptionType exceptionType, final Object... messageArguments) {
        LOG.error(MessageFormat.format(exceptionType.getMessage(), messageArguments));
        return new TerminologyServerException(exceptionType, messageArguments);
    }
}

步骤4 -在应用程序的任何位置,您现在可以抛出异常,这将在应用程序日志中记录异常.由于Spring @ControllerAdvice注释,DefaultExceptionHandler抛出并拾取此异常:

throw ExceptionFactory.create(ExceptionType.INTERNAL_SERVER_ERROR);

像这样,您可以将异常处理流程作为一个跨领域的问题来应对.不会将内部服务器错误传播给最终用户,并且DefaultExceptionHandler会处理预期和意外异常.异常被分配了一个HTTP错误代码和错误消息,它将返回给客户端.