Spring MVC REST通过返回JSON处理错误的网址(404) [英] Spring MVC REST Handing Bad Url (404) by returning JSON

问题描述

我正在使用SpringMVC开发REST服务，其中在类和方法级别具有@RequestMapping.

I am developing a REST service using SpringMVC, where I have @RequestMapping at class and method level.

此应用程序当前配置为返回在web.xml中配置的错误页面jsp.

This application is currently configured to return error-page jsp configured in web.xml.

<error-page>
    <error-code>404</error-code>
    <location>/resourceNotFound</location>
</error-page>

但是我想返回自定义JSON而不是此错误页面.

I however want to return custom JSON instead of this error page.

通过在控制器中编写此代码，我能够处理异常并为其他异常返回json，但不确定在URL根本不存在时如何以及在何处编写返回JSON的逻辑.

I am able to handle exception and return json for other exceptions, by writing this in controller, but not sure how and where to write the logic to return JSON when the url does not exist at all.

    @ExceptionHandler(TypeMismatchException.class)
        @ResponseStatus(value=HttpStatus.NOT_FOUND)
        @ResponseBody
        public ResponseEntity<String> handleTypeMismatchException(HttpServletRequest req, TypeMismatchException ex) {

            HttpHeaders headers = new HttpHeaders();
            headers.add("Content-Type", "application/json; charset=utf-8");
            Locale locale = LocaleContextHolder.getLocale();
            String errorMessage = messageSource.getMessage("error.patient.bad.request", null, locale);

            errorMessage += ex.getValue();
            String errorURL = req.getRequestURL().toString();

            ErrorInfo errorInfo = new ErrorInfo(errorURL, errorMessage);
            return new ResponseEntity<String>(errorInfo.toJson(), headers, HttpStatus.BAD_REQUEST);

        }

我尝试了@ControllerAdvice，它适用于其他异常情况，但不适用于无法映射的情况，

@ControllerAdvice
public class RestExceptionProcessor {

    @Autowired
    private MessageSource messageSource;

    @ExceptionHandler(HttpRequestMethodNotSupportedException.class)
    @ResponseStatus(value=HttpStatus.NOT_FOUND)
    @ResponseBody
    public ResponseEntity<String> requestMethodNotSupported(HttpServletRequest req, HttpRequestMethodNotSupportedException ex) {
        Locale locale = LocaleContextHolder.getLocale();
        String errorMessage = messageSource.getMessage("error.patient.bad.id", null, locale);

        String errorURL = req.getRequestURL().toString();

        ErrorInfo errorInfo = new ErrorInfo(errorURL, errorMessage);
        return new ResponseEntity<String>(errorInfo.toJson(), HttpStatus.BAD_REQUEST);
    }

    @ExceptionHandler(NoSuchRequestHandlingMethodException.class)
    @ResponseStatus(value=HttpStatus.NOT_FOUND)
    @ResponseBody
    public ResponseEntity<String> requestHandlingMethodNotSupported(HttpServletRequest req, NoSuchRequestHandlingMethodException ex) {
        Locale locale = LocaleContextHolder.getLocale();
        String errorMessage = messageSource.getMessage("error.patient.bad.id", null, locale);

        String errorURL = req.getRequestURL().toString();

        ErrorInfo errorInfo = new ErrorInfo(errorURL, errorMessage);
        return new ResponseEntity<String>(errorInfo.toJson(), HttpStatus.BAD_REQUEST);
    }


}

推荐答案

在SpringFramework中研究了DispatcherServlet和HttpServletBean.init()之后，我发现在Spring 4中它是可能的.

After digging around DispatcherServlet and HttpServletBean.init() in SpringFramework I see that its possible in Spring 4.

org.springframework.web.servlet.DispatcherServlet

/** Throw a NoHandlerFoundException if no Handler was found to process this request? **/
private boolean throwExceptionIfNoHandlerFound = false;

protected void noHandlerFound(HttpServletRequest request, HttpServletResponse response) throws Exception {
    if (pageNotFoundLogger.isWarnEnabled()) {
        String requestUri = urlPathHelper.getRequestUri(request);
        pageNotFoundLogger.warn("No mapping found for HTTP request with URI [" + requestUri +
                "] in DispatcherServlet with name '" + getServletName() + "'");
    }
    if(throwExceptionIfNoHandlerFound) {
        ServletServerHttpRequest req = new ServletServerHttpRequest(request);
        throw new NoHandlerFoundException(req.getMethod().name(),
                req.getServletRequest().getRequestURI(),req.getHeaders());
    } else {
        response.sendError(HttpServletResponse.SC_NOT_FOUND);
    }
}

throwExceptionIfNoHandlerFound 默认为false，我们应该在 web.xml

throwExceptionIfNoHandlerFound is false by default and we should enable that in web.xml

<servlet>
    <servlet-name>appServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>throwExceptionIfNoHandlerFound</param-name>
            <param-value>true</param-value>
        </init-param>
    <load-on-startup>1</load-on-startup>
    <async-supported>true</async-supported>
</servlet>

然后您可以使用此方法将其捕获到带有 @ControllerAdvice 注释的类中.

And then you can catch it in a class annotated with @ControllerAdvice using this method.

@ExceptionHandler(NoHandlerFoundException.class)
@ResponseStatus(value=HttpStatus.NOT_FOUND)
@ResponseBody
public ResponseEntity<String> requestHandlingNoHandlerFound(HttpServletRequest req, NoHandlerFoundException ex) {
    Locale locale = LocaleContextHolder.getLocale();
    String errorMessage = messageSource.getMessage("error.bad.url", null, locale);

    String errorURL = req.getRequestURL().toString();

    ErrorInfo errorInfo = new ErrorInfo(errorURL, errorMessage);
    return new ResponseEntity<String>(errorInfo.toJson(), HttpStatus.BAD_REQUEST);
}

这允许我为不存在映射的错误URL返回JSON响应，而不是重定向到JSP页面:)

Which allows me to return JSON response for bad URLs for which no mapping exist, instead of redirecting to a JSP page :)

{"message":"URL does not exist","url":"http://localhost:8080/service/patientssd"}

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