spring boot 异常处理-蒲公英云

spring boot 异常处理

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"));
    }
}