SpringBoot初始教程之统一异常处理

Posted 夜宿山寺

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SpringBoot初始教程之统一异常处理(三)

1.介绍

在日常开发中发生了异常,往往是需要通过一个统一的异常处理处理所有异常,来保证客户端能够收到友好的提示。SpringBoot在页面
发生异常的时候会自动把请求转到/error,SpringBoot内置了一个BasicErrorController对异常进行统一的处理,当然也可以自定义这个路径

application.yaml


server:
  port: 8080
  error:
    path: /custom/error

BasicErrorController提供两种返回错误一种是页面返回、当你是页面请求的时候就会返回页面,另外一种是json请求的时候就会返回json错误


    @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);
    

分别会有如下两种返回



  "timestamp": 1478571808052,
  "status": 404,
  "error": "Not Found",
  "message": "No message available",
  "path": "/rpc"


2.通用Exception处理

通过使用@ControllerAdvice来进行统一异常处理,@ExceptionHandler(value = Exception.class)来指定捕获的异常
下面针对两种异常进行了特殊处理分别返回页面和json数据,使用这种方式有个局限,无法根据不同的头部返回不同的数据格式,而且无法针对404、403等多种状态进行处理


    @ControllerAdvice
    public class GlobalExceptionHandler 
        public static final String DEFAULT_ERROR_VIEW = "error";
        @ExceptionHandler(value = CustomException.class)
        @ResponseBody
        public ResponseEntity defaultErrorHandler(HttpServletRequest req, CustomException e) throws Exception 
            return ResponseEntity.ok("ok");
        
        @ExceptionHandler(value = Exception.class)
        public ModelAndView defaultErrorHandler(HttpServletRequest req, Exception e) throws Exception 
            ModelAndView mav = new ModelAndView();
            mav.addObject("exception", e);
            mav.addObject("url", req.getRequestURL());
            mav.setViewName(DEFAULT_ERROR_VIEW);
            return mav;
        
    


3.自定义BasicErrorController 错误处理

在初始介绍哪里提到了BasicErrorController,这个是SpringBoot的默认错误处理,也是一种全局处理方式。咱们可以模仿这种处理方式自定义自己的全局错误处理
下面定义了一个自己的BasicErrorController,可以根据自己的需求自定义errorHtml()error()的返回值。


    @Controller
    @RequestMapping("$server.error.path:$error.path:/error")
    public class BasicErrorController extends AbstractErrorController 
        private final ErrorProperties errorProperties;
        private static final Logger LOGGER = LoggerFactory.getLogger(BasicErrorController.class);
        @Autowired
        private ApplicationContext applicationContext;

        /**
         * Create a new @link org.springframework.boot.autoconfigure.web.BasicErrorController instance.
         *
         * @param errorAttributes the error attributes
         * @param errorProperties configuration properties
         */
        public BasicErrorController(ErrorAttributes errorAttributes,
                                    ErrorProperties errorProperties) 
            this(errorAttributes, errorProperties,
                    Collections.<ErrorViewResolver>emptyList());
        

        /**
         * Create a new @link org.springframework.boot.autoconfigure.web.BasicErrorController instance.
         *
         * @param errorAttributes    the error attributes
         * @param errorProperties    configuration properties
         * @param errorViewResolvers error view resolvers
         */
        public BasicErrorController(ErrorAttributes errorAttributes,
                                    ErrorProperties errorProperties, List<ErrorViewResolver> errorViewResolvers) 
            super(errorAttributes, errorViewResolvers);
            Assert.notNull(errorProperties, "ErrorProperties must not be null");
            this.errorProperties = errorProperties;
        

        @Override
        public String getErrorPath() 
            return this.errorProperties.getPath();
        

        @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);
            insertError(request);
            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);
            insertError(request);
            return new ResponseEntity(body, status);
        

        /**
         * Determine if the stacktrace attribute should be included.
         *
         * @param request  the source request
         * @param produces the media type produced (or @code MediaType.ALL)
         * @return if the stacktrace attribute should be included
         */
        protected boolean isIncludeStackTrace(HttpServletRequest request,
                                              MediaType produces) 
            ErrorProperties.IncludeStacktrace include = getErrorProperties().getIncludeStacktrace();
            if (include == ErrorProperties.IncludeStacktrace.ALWAYS) 
                return true;
            
            if (include == ErrorProperties.IncludeStacktrace.ON_TRACE_PARAM) 
                return getTraceParameter(request);
            
            return false;
        

        /**
         * Provide access to the error properties.
         *
         * @return the error properties
         */
        protected ErrorProperties getErrorProperties() 
            return this.errorProperties;
        
    

SpringBoot提供了一种特殊的Bean定义方式,可以让我们容易的覆盖已经定义好的Controller,原生的BasicErrorController是定义在ErrorMvcAutoConfiguration中的
具体代码如下:


    @Bean
    @ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
    public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) 
        return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
                this.errorViewResolvers);
    

可以看到这个注解@ConditionalOnMissingBean 意思就是定义这个bean 当 ErrorController.class 这个没有定义的时候,
意思就是说只要我们在代码里面定义了自己的ErrorController.class时,这段代码就不生效了,具体自定义如下:


    @Configuration
    @ConditionalOnWebApplication
    @ConditionalOnClass(Servlet.class, DispatcherServlet.class)
    @AutoConfigureBefore(WebMvcAutoConfiguration.class)
    @EnableConfigurationProperties(ResourceProperties.class)
    public class ConfigSpringboot 
        @Autowired(required = false)
        private List<ErrorViewResolver> errorViewResolvers;
        private final ServerProperties serverProperties;

        public ConfigSpringboot(
                ServerProperties serverProperties) 
            this.serverProperties = serverProperties;
        

        @Bean
        public MyBasicErrorController basicErrorController(ErrorAttributes errorAttributes) 
            return new MyBasicErrorController(errorAttributes, this.serverProperties.getError(),
                    this.errorViewResolvers);
        


    

在使用的时候需要注意MyBasicErrorController不能被自定义扫描Controller扫描到,否则无法启动。

3.总结

一般来说自定义BasicErrorController这种方式比较实用,因为可以通过不同的头部返回不同的数据格式,在配置上稍微复杂一些,但是从实用的角度来说比较方便而且可以定义通用组件

本文代码

https://git.oschina.net/wangkang_daydayup/SpringBoot-Learn/tree/master

springboot-3

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