Spring Boot 全局异常处理（400/404/500），顺便解决过滤器中异常未捕获到的问题，让RestApi 任何时候都能获取统一的格式代码

出发点是为了在系统抛出异常的时候，前端仍然可以获取到统一的报文格式，所以后端所有的异常都得捕获，并处理

Spring boot 在处理异常的时候，500/404默认都会转发到/error,而这个异常的处理类是

ErrorController，所以我们重写一个

ErrorController的子类即可：

@RestController
public class GlobalExceptionController extends AbstractErrorController {
    private static final Logger LOGGER = LoggerFactory.getLogger(GlobalExceptionController.class);
    private static final String ERROR_PATH = "/error";

    public GlobalExceptionController(ErrorAttributes errorAttributes) {
        super(errorAttributes);
    }

    @Override
    public String getErrorPath() {
        return ERROR_PATH;
    }

    @RequestMapping(value = ERROR_PATH)
    public Response error(HttpServletRequest request) {
        WebRequest webRequest = new ServletWebRequest(request);
        Throwable e = getError(webRequest);
        if (e == null) {
            Map attributes = getErrorAttributes(request, false);
            Object timestamp = attributes.get("timestamp");
            Object status = attributes.get("status");
            String error = attributes.get("error").toString();
            Object path = attributes.get("path");
            LOGGER.error("status {} error {} path{} timestamp {}", status, error, path, timestamp);
            return Response.failure(Integer.parseInt(status.toString()), error);
        }
        if (e instanceof TokenExpiredException) {
            TokenExpiredException tokenExpiredException = (TokenExpiredException) e;
            return Response.failure(tokenExpiredException.getHttpStatus().value(), tokenExpiredException.getHttpStatus().getReasonPhrase());
        } else if (e instanceof CodeException) {
            CodeException codeException = (CodeException) e;
            String message = e.getMessage();
            if (StringUtils.isEmpty(message)) {
                message = String.format("[%s][%s]", codeException.getErrCode(), codeException.getErrMsg());
            }
            return Response.failure(message);
        } else {
            return Response.failure("系统繁忙,请稍后再试");
        }
    }

    private Throwable getError(WebRequest webRequest) {
        return (Throwable) this.getAttribute(webRequest, "javax.servlet.error.exception");
    }

    private Object getAttribute(RequestAttributes requestAttributes, String name) {
        return requestAttributes.getAttribute(name, 0);
    }
}