@RestController
@RequestMapping(value = "/hello")
public class HelloWorldController {
  @RequestMapping("/test")
  public Object getObject1(HttpServletRequest request){
    Response response = new Response();
    response.success("請(qǐng)求成功...");
    response.setResponseTime();
    return response;
  }
}

{
 "timestamp": "2020-11-19T08:30:48.844+0000",
 "status": 404,
 "error": "Not Found",
 "message": "No message available",
 "path": "/hello/test1"
}

{
  "rtnCode":"9999",
  "rtnMsg":"404 /hello/test1 Not Found"
}

{
 "timestamp": "2020-11-19T08:30:48.844+0000",
 "status": 404,
 "error": "Not Found",
 "message": "No message available",
 "path": "/hello/test1"
}

... 省略部分代碼....
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
... 省略部分代碼

@Override
@Nullable
public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler)
  throws Exception {
  ((HttpRequestHandler) handler).handleRequest(request, response);
  return null;
}

@Override
public void handleRequest(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {

  // For very general mappings (e.g. "/") we need to check 404 first
  Resource resource = getResource(request);
  if (resource == null) {
    logger.trace("No matching resource found - returning 404");
    // 這個(gè)方法很簡(jiǎn)單，就是設(shè)置404響應(yīng)碼，然后將Response的errorState狀態(tài)從0設(shè)置成1
    response.sendError(HttpServletResponse.SC_NOT_FOUND);
    // 直接返回
    return;
  }
  ... 省略部分方法
}

{
 "timestamp": "2020-11-19T08:30:48.844+0000",
 "status": 404,
 "error": "Not Found",
 "message": "No message available",
 "path": "/hello/test1"
}

@Override
public final void invoke(Request request, Response response)
  throws IOException, ServletException {
  
  Context context = request.getContext();
  if (context == null) {
    response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
              sm.getString("standardHost.noContext"));
    return;
  }

  if (request.isAsyncSupported()) {
    request.setAsyncSupported(context.getPipeline().isAsyncSupported());
  }

  boolean asyncAtStart = request.isAsync();
  boolean asyncDispatching = request.isAsyncDispatching();

  try {
    context.bind(Globals.IS_SECURITY_ENABLED, MY_CLASSLOADER);
    if (!asyncAtStart && !context.fireRequestInitEvent(request.getRequest())) {
      return;
    }
    try {
      if (!asyncAtStart || asyncDispatching) {
        context.getPipeline().getFirst().invoke(request, response);
      } else {
        if (!response.isErrorReportRequired()) {
          throw new IllegalStateException(sm.getString("standardHost.asyncStateError"));
        }
      }
    } catch (Throwable t) {
      ExceptionUtils.handleThrowable(t);
      container.getLogger().error("Exception Processing " + request.getRequestURI(), t);
      if (!response.isErrorReportRequired()) {
        request.setAttribute(RequestDispatcher.ERROR_EXCEPTION, t);
        throwable(request, response, t);
      }
    }
    response.setSuspended(false);

    Throwable t = (Throwable) request.getAttribute(RequestDispatcher.ERROR_EXCEPTION);
    if (!context.getState().isAvailable()) {
      return;
    }
    // 在這里判斷請(qǐng)求是不是發(fā)生了錯(cuò)誤，錯(cuò)誤的話就進(jìn)入StandardHostValve的status(Request request, Response response)方法。
    // Look for (and render if found) an application level error page
    if (response.isErrorReportRequired()) {
      if (t != null) {
        throwable(request, response, t);
      } else {
        status(request, response);
      }
    }

    if (!request.isAsync() && !asyncAtStart) {
      context.fireRequestDestroyEvent(request.getRequest());
    }
  } finally {
    // Access a session (if present) to update last accessed time, based
    // on a strict interpretation of the specification
    if (ACCESS_SESSION) {
      request.getSession(false);
    }
    context.unbind(Globals.IS_SECURITY_ENABLED, MY_CLASSLOADER);
  }
 }

 private boolean custom(Request request, Response response,
               ErrorPage errorPage) {

    if (container.getLogger().isDebugEnabled()) {
      container.getLogger().debug("Processing " + errorPage);
    }
    try {
      // Forward control to the specified location
      ServletContext servletContext =
        request.getContext().getServletContext();
      RequestDispatcher rd =
        servletContext.getRequestDispatcher(errorPage.getLocation());
      if (rd == null) {
        container.getLogger().error(
          sm.getString("standardHostValue.customStatusFailed", errorPage.getLocation()));
        return false;
      }
      if (response.isCommitted()) {
        rd.include(request.getRequest(), response.getResponse());
      } else {
        // Reset the response (keeping the real error code and message)
        response.resetBuffer(true);
        response.setContentLength(-1);
        // 1: 重新forward請(qǐng)求到/error接口
        rd.forward(request.getRequest(), response.getResponse());
        response.setSuspended(false);
      }
      return true;
    } catch (Throwable t) {
      ExceptionUtils.handleThrowable(t);
      container.getLogger().error("Exception Processing " + errorPage, t);
      return false;
    }
  }

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
  @RequestMapping(produces = "text/html")
  public ModelAndView errorHtml(HttpServletRequest request,
      HttpServletResponse response) {
    HttpStatus status = getStatus(request);
    Map<String, Object> model = Collections.unmodifiableMap(getErrorAttributes(
        request, isIncludeStackTrace(request, MediaType.TEXT_HTML)));
    response.setStatus(status.value());
    ModelAndView modelAndView = resolveErrorView(request, response, status, model);
    return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
  }

  @RequestMapping
  @ResponseBody
  public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
    Map<String, Object> body = getErrorAttributes(request,
        isIncludeStackTrace(request, MediaType.ALL));
    HttpStatus status = getStatus(request);
    return new ResponseEntity<Map<String, Object>>(body, status);
  }
  ... 省略部分方法
}

@Configuration
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
// Load before the main WebMvcAutoConfiguration so that the error View is available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class })
public class ErrorMvcAutoConfiguration {
  
  @Bean
	@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
	public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) {
		return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
				this.errorViewResolvers);
	}
	... 省略部分代碼
}

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class CustomErrorController extends BasicErrorController {

  @Value("${server.error.path:${error.path:/error}}")
  private String path;

  public CustomErrorController(ServerProperties serverProperties) {
    super(new DefaultErrorAttributes(), serverProperties.getError());
  }

  /**
   * 覆蓋默認(rèn)的JSON響應(yīng)
   */
  @Override
  public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {

    HttpStatus status = getStatus(request);
    Map<String, Object> map = new HashMap<String, Object>(16);
    Map<String, Object> originalMsgMap = getErrorAttributes(request, isIncludeStackTrace(request, MediaType.ALL));
    String path = (String)originalMsgMap.get("path");
    String error = (String)originalMsgMap.get("error");
    String message = (String)originalMsgMap.get("message");
    StringJoiner joiner = new StringJoiner(",","[","]");
    joiner.add(path).add(error).add(message);
    map.put("rtnCode", "9999");
    map.put("rtnMsg", joiner.toString());
    return new ResponseEntity<Map<String, Object>>(map, status);
  }

  /**
   * 覆蓋默認(rèn)的HTML響應(yīng)
   */
  @Override
  public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
    //請(qǐng)求的狀態(tài)
    HttpStatus status = getStatus(request);
    response.setStatus(getStatus(request).value());
    Map<String, Object> model = getErrorAttributes(request,
        isIncludeStackTrace(request, MediaType.TEXT_HTML));
    ModelAndView modelAndView = resolveErrorView(request, response, status, model);
    //指定自定義的視圖
    return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
  }
}

server:
 error:
  path: /xxx