spring boot 异常处理

阳光穿透心脏的1/2处 2022-08-21 12:48 2阅读 0赞

spring boot在异常的处理中，默认实现了一个EmbeddedServletContainerCustomizer并定义了一个错误页面到”/error”中，在ErrorMvcAutoConfiguration源码中可以看到

/** * {@link EmbeddedServletContainerCustomizer} that configures the container's error * pages. */
    private static class ErrorPageCustomizer implements EmbeddedServletContainerCustomizer, Ordered { 
    
        private final ServerProperties properties;
    
        protected ErrorPageCustomizer(ServerProperties properties) {
            this.properties = properties;
        }
    
        @Override
        public void customize(ConfigurableEmbeddedServletContainer container) {
            container.addErrorPages(new ErrorPage(this.properties.getServletPrefix()
                    + this.properties.getError().getPath()));
        }
    
        @Override
        public int getOrder() {
            return 0;
        }
    
    }

还配置了一个默认的白板页面，在源码可以看到

@Configuration
    @ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
    @Conditional(ErrorTemplateMissingCondition.class)
    protected static class WhitelabelErrorViewConfiguration { 
    
        private final SpelView defaultErrorView = new SpelView(
                "<html><body><h1>Whitelabel Error Page</h1>"
                        + "<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>"
                        + "<div id='created'>${timestamp}</div>"
                        + "<div>There was an unexpected error (type=${error}, status=${status}).</div>"
                        + "<div>${message}</div></body></html>");
    
        @Bean(name = "error")
        @ConditionalOnMissingBean(name = "error")
        public View defaultErrorView() {
            return this.defaultErrorView;
        }
    
        // If the user adds @EnableWebMvc then the bean name view resolver from
        // WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
        @Bean
        @ConditionalOnMissingBean(BeanNameViewResolver.class)
        public BeanNameViewResolver beanNameViewResolver() {
            BeanNameViewResolver resolver = new BeanNameViewResolver();
            resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
            return resolver;
        }
    
    }

在路径的处理上，定义了一个BasicErrorController来处理异常，ErrorAttributes来装载错误异常到前端

@Controller
    @RequestMapping("${server.error.path:${error.path:/error}}")
    public class BasicErrorController extends AbstractErrorController { 
    
        private final ErrorProperties errorProperties;
    
        //...
    
        @RequestMapping(produces = "text/html")
        public ModelAndView errorHtml(HttpServletRequest request,
                HttpServletResponse response) {
            response.setStatus(getStatus(request).value());
            Map<String, Object> model = getErrorAttributes(request,
                    isIncludeStackTrace(request, MediaType.TEXT_HTML));
            return new ModelAndView("error", model);
        }
    
        @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);
        }
    
        //...
    }

默认只要你请求的content-type是”text/html”则返回一个白版页面给你，如果是其他的content-type，则返回一个json的数据给你。

若你想自定义异常，可以通过以下方式来处理

1.你可以默认在classpath:templates下定义一个error.ftl的freemarker模版来定义异常页面

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8">
    <title>Insert title here</title>
    </head>
    <body>
    
     <h1> error page !! </h1>
    
     ${timestamp?string('yyyy-MM-dd HH:mm:ss')}<br/><br/>
     ${status} <br/><br/>
     ${error} <br/><br/>
     ${message} <br/><br/>
     ${path} <br/><br/>
    
    </body>
    </html>

2.可以利用@ExceptionHandler来为某个特定的controller拦截异常，并返回一个json数据，当然你也可以定义全部的controller来拦截异常

@ControllerAdvice(basePackageClasses = FooController.class)
    public class FooControllerAdvice extends ResponseEntityExceptionHandler { 
    
        @ExceptionHandler(YourException.class)
        @ResponseBody
        ResponseEntity<?> handleControllerException(HttpServletRequest request, Throwable ex) {
            HttpStatus status = getStatus(request);
            return new ResponseEntity<>(new CustomErrorType(status.value(), ex.getMessage()), status);
        }
    
        private HttpStatus getStatus(HttpServletRequest request) {
            Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
            if (statusCode == null) {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }
            return HttpStatus.valueOf(statusCode);
        }
    
    }

3.还可以自定义server的错误页面

@Bean
    public EmbeddedServletContainerCustomizer containerCustomizer(){
        return new MyCustomizer();
    }
    
    // ...
    
    private static class MyCustomizer implements EmbeddedServletContainerCustomizer { 
    
        @Override
        public void customize(ConfigurableEmbeddedServletContainer container) {
            container.addErrorPages(new ErrorPage(HttpStatus.BAD_REQUEST, "/500"));
        }
    
    }