默认效果：
1）、浏览器，返回一个默认的错误页面
浏览器发送请求的请求头：
2）、如果是其他客户端，默认响应一个json数据
原理：
可以参照ErrorMvcAutoConfiguration；错误处理的自动配置；
给容器中添加了以下组件
1、DefaultErrorAttributes：
代码语言：javascript复制帮我们在页面共享信息；
@Override
public Map<String, Object> getErrorAttributes(RequestAttributes requestAttributes,
boolean includeStackTrace) {
Map<String, Object> errorAttributes = new LinkedHashMap<String, Object>();
errorAttributes.put("timestamp", new Date());
addStatus(errorAttributes, requestAttributes);
addErrorDetails(errorAttributes, requestAttributes, includeStackTrace);
addPath(errorAttributes, requestAttributes);
return errorAttributes;
}2、BasicErrorController：处理默认/error请求
代码语言：javascript复制@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
@RequestMapping(produces = "text/html")//产生html类型的数据；浏览器发送的请求来到这个方法处理
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());
//去哪个页面作为错误页面；包含页面地址和页面内容
ModelAndView modelAndView = resolveErrorView(request, response, status, model);
return (modelAndView == null ? new ModelAndView("error", model) : modelAndView);
}
@RequestMapping
@ResponseBody //产生json数据，其他客户端来到这个方法处理；
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);
}3、ErrorPageCustomizer：
代码语言：javascript复制 @Value("${error.path:/error}")
private String path = "/error"; 系统出现错误以后来到error请求进行处理；（web.xml注册的错误页面规则）4、DefaultErrorViewResolver：
代码语言：javascript复制@Override
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status,
Map<String, Object> model) {
ModelAndView modelAndView = resolve(String.valueOf(status), model);
if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
modelAndView = resolve(SERIES_VIEWS.get(status.series()), model);
}
return modelAndView;
}
private ModelAndView resolve(String viewName, Map<String, Object> model) {
//默认SpringBoot可以去找到一个页面？ error/404
String errorViewName = "error/" viewName;
//模板引擎可以解析这个页面地址就用模板引擎解析
TemplateAvailabilityProvider provider = this.templateAvailabilityProviders
.getProvider(errorViewName, this.applicationContext);
if (provider != null) {
//模板引擎可用的情况下返回到errorViewName指定的视图地址
return new ModelAndView(errorViewName, model);
}
//模板引擎不可用，就在静态资源文件夹下找errorViewName对应的页面 error/404.html
return resolveResource(errorViewName, model);
}步骤：
一但系统出现4xx或者5xx之类的错误；ErrorPageCustomizer就会生效（定制错误的响应规则）；就会来到/error请求；就会被BasicErrorController处理；
1）响应页面；去哪个页面是由DefaultErrorViewResolver解析得到的；
代码语言：javascript复制protected ModelAndView resolveErrorView(HttpServletRequest request,
HttpServletResponse response, HttpStatus status, Map<String, Object> model) {
//所有的ErrorViewResolver得到ModelAndView
for (ErrorViewResolver resolver : this.errorViewResolvers) {
ModelAndView modelAndView = resolver.resolveErrorView(request, status, model);
if (modelAndView != null) {
return modelAndView;
}
}
return null;
}
