在客户端处理REST异常

Question

在Spring MVC应用程序中，我试图通过rest响应来处理传递给客户端的异常，但找不到任何可行的解决方案。

服务器端控制器：

@RestController
public class MessageProducerController {

    @Autowired
    private MessageService service;

    @RequestMapping(value = "/messageApp-api/getMessage/{id}", produces = "application/json")
    public Message restGetMessage(@PathVariable long id) {

        Message message = service.findSingleMessage(id).orElse(EMPTY_MESSAGE);
        if (EMPTY_MESSAGE.equals(message)) {
            throw new MessageNotFoundException(id);
        }

        return message;
    }
}

异常类：

public class MessageNotFoundException extends RuntimeException {
    public MessageNotFoundException(long id) {
        super(String.format("Message id=%d not found", id));
    }
}

ApiError类：

public class ApiError {
    private HttpStatus status;
    private String message;

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

    public HttpStatus getStatus() {
        return status;
    }

    public String getMessage() {
        return message;
    }
}

RestResponseException类：

@Component
@ControllerAdvice
public class RestResponseException {
    @ExceptionHandler(MessageNotFoundException.class)
    public ResponseEntity<Object> messageNotFound(MessageNotFoundException e) {
        ApiError apiError = new ApiError(HttpStatus.NOT_FOUND, e.getMessage());
        return new ResponseEntity<>(apiError, new HttpHeaders(), apiError.getStatus());
    }
}

客户端控制器：

@Controller
public class MessageClientController {

    private static final String MESSAGE = "restMessage";
    private static final String MESSAGES = "restMessages";
    private static final String ERROR = "error";

    @RequestMapping(value = "/messageApp-api/getMessage/{id}")
    public String restGetMessage(@PathVariable long id, Model model) {

        String view = MESSAGE;

        try {
            RestTemplate rest = new RestTemplate();
            ResponseEntity<Message> response =
                    rest.getForEntity("http://localhost:80/messageApp-api/getMessage/{id}", Message.class, id);

            if (HttpStatus.OK == response.getStatusCode()) {
                model.addAttribute(MESSAGE, response.getBody());
            } else if (HttpStatus.NOT_FOUND == response.getStatusCode()) {
                model.addAttribute(MESSAGE, EMPTY_MESSAGE);
            }
        } catch (Exception e) {
            e.printStackTrace();
            view = ERROR;
        }

        return view;
    }
}

这个想法是检查响应状态，并根据它做出有关模型的进一步步骤。但是，事实上，当找不到具有某个id的消息时，rest.getForEntity（“http://localhost:80/messageApp-api/getMessage/ {id}”，Message.class，id）会抛出以下异常：

org.springframework.web.client.HttpClientErrorException: 404 null
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:91)
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:667)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:620)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:580)
    at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:312)
    at messageApp.controllers.rest.MessageClientController.restGetMessage(MessageClientController.java:34)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:220)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:116)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:317)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:150)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:214)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1455)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

那么，如何防止响应中的异常被抛出以及如何从响应中检索httpStatus？..

Answer 1

这是一种误解，我也遇到过。看起来好像您可以在ResponseEntity中反省状态代码以获取错误。但事实并非如此。

您可以捕获HttpStatusCodeException，只要响应状态代码为＆gt; = 400，就会抛出该异常。然后，您可以从异常中获取状态代码。

  try {
        RestTemplate rest = new RestTemplate();
        ResponseEntity<Message> response =
                rest.getForEntity("http://localhost:80/messageApp-api/getMessage/{id}", Message.class, id);

        model.addAttribute(MESSAGE, response.getBody());
    } catch (HttpStatusCodeException e) {
      if (HttpStatus.NOT_FOUND == e.getStatusCode()) {
          model.addAttribute(MESSAGE, EMPTY_MESSAGE);
      }
      //handle other errors here
    }

HttpStatusCodeException有两个子类。

针对客户端错误抛出

HttpClientErrorException（400＆lt; = status code＆lt; 500）

HttpServerErrorException因服务器错误而被抛出（状态代码＆gt; = 500）