SpringBoot2.0—错误处理原理&定制错误页面
- SpringBoot默认的错误处理机制
- 如何定制错误响应:
SpringBoot默认的错误处理机制
默认效果:
1).返回一个默认的错误页面
2).如果是其他客户端,默认返回json数据
原理:
可以参照ErrorMvcAutoConfiguration,该类添加了如下组件
1).DefaultErrorAttributes
@Bean
@ConditionalOnMissingBean(
value = {ErrorAttributes.class},
search = SearchStrategy.CURRENT
)
public DefaultErrorAttributes errorAttributes() {
return new DefaultErrorAttributes(this.serverProperties.getError().isIncludeException());
}2).BasicErrorController
@Bean
@ConditionalOnMissingBean(
value = {ErrorController.class},
search = SearchStrategy.CURRENT
)
public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) {
return new BasicErrorController(errorAttributes, this.serverProperties.getError(), this.errorViewResolvers);
}3).ErrorPageCustomizer
@Bean
public ErrorMvcAutoConfiguration.ErrorPageCustomizer errorPageCustomizer() {
return new ErrorMvcAutoConfiguration.ErrorPageCustomizer(this.serverProperties, this.dispatcherServletPath);
}4).DefaultErrorViewResolver
@Bean
@ConditionalOnBean({DispatcherServlet.class})
@ConditionalOnMissingBean
public DefaultErrorViewResolver conventionErrorViewResolver() {
return new DefaultErrorViewResolver(this.applicationContext, this.resourceProperties);
}步骤:
4.1).系统出现4xx或者5xx之类的错误,ErrorPageCustomizer就会生效,作用定制错误的响应规则
@Value("${error.path:/error}")
//系统出现错误来到error请求进行处理
private String path = "/error";4.2).来到error请求后,由BasicErrorController进行处理
@Controller
@RequestMapping({"${server.error.path:${error.path:/error}}"})
public class BasicErrorController extends AbstractErrorController {而BasicErrorController中有以下两种请求:返回html页面和json数据
@RequestMapping(
produces = {"text/html"}
)
public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
HttpStatus status = this.getStatus(request);
Map<String, Object> model = Collections.unmodifiableMap(this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.TEXT_HTML)));
response.setStatus(status.value());
//去哪个页面作为错误页面
ModelAndView modelAndView = this.resolveErrorView(request, response, status, model);
return modelAndView != null ? modelAndView : new ModelAndView("error", model);
}
@RequestMapping
public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
Map<String, Object> body = this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.ALL));
HttpStatus status = this.getStatus(request);
return new ResponseEntity(body, status);
}如何区分是发送html还是json的?
根据浏览器发请求的请求头text/html,而其他客户端发送的请求头/*
怎么去错误页面?
protected ModelAndView resolveErrorView(HttpServletRequest request, HttpServletResponse response, HttpStatus status, Map<String, Object> model) {
Iterator var5 = this.errorViewResolvers.iterator();
ModelAndView modelAndView;
do {
if (!var5.hasNext()) {
return null;
}
ErrorViewResolver resolver = (ErrorViewResolver)var5.next();
modelAndView = resolver.resolveErrorView(request, status, model);
} while(modelAndView == null);
return modelAndView;
}得到所有的ErrorViewResolver 异常视图解析器,得到modelAndView
4.3 ).去哪个页面,由DefaultErrorViewResolver解析得到的
static {
Map<Series, String> views = new EnumMap(Series.class);
views.put(Series.CLIENT_ERROR, "4xx");
views.put(Series.SERVER_ERROR, "5xx");
SERIES_VIEWS = Collections.unmodifiableMap(views);
}
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model) {
ModelAndView modelAndView = this.resolve(String.valueOf(status.value()), model);
if (modelAndView == null && SERIES_VIEWS.containsKey(status.series())) {
modelAndView = this.resolve((String)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 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);
//模板引擎可用的返回errorViewName 指定的视图地址,不可以用调用resolveResource在静态文件夹下找errorViewName 对应的页面error/404.html
return provider != null ? new ModelAndView(errorViewName, model) : this.resolveResource(errorViewName, model);
}resolveResource在(this.resourceProperties.getStaticLocations())静态文件夹下找
errorViewName 对应的页面error/404.html
private ModelAndView resolveResource(String viewName, Map<String, Object> model) {
String[] var3 = this.resourceProperties.getStaticLocations();
int var4 = var3.length;
for(int var5 = 0; var5 < var4; ++var5) {
String location = var3[var5];
try {
Resource resource = this.applicationContext.getResource(location);
resource = resource.createRelative(viewName + ".html");
if (resource.exists()) {
return new ModelAndView(new DefaultErrorViewResolver.HtmlResourceView(resource), model);
}
} catch (Exception var8) {
}
}
return null;
}如何定制错误响应:
1).如何定制错误的页面:
1.1).a.有模板引擎的情况下,将错误页面命名为错误状态码.html,放在模板引擎文件夹里面的error文件夹下 error/状态码.html
b.我们还可以定制 4xx.html 和5xx作为错误页面来匹配这种类型的所有错误,有精确的(404.html)优先精确的页面
页面能获取的信息
timestamp：时间戳
status：状态码
error：错误提示
exception：异常对象
message：异常消息
errors：JSR303数据校验的错误都在这里
通过DefaultErrorAttributes获取
帮我们在页面共享信息；
public Map<String, Object> getErrorAttributes(ServerRequest request, boolean includeStackTrace) {
Map<String, Object> errorAttributes = new LinkedHashMap();
errorAttributes.put("timestamp", new Date());
errorAttributes.put("path", request.path());
Throwable error = this.getError(request);
HttpStatus errorStatus = this.determineHttpStatus(error);
errorAttributes.put("status", errorStatus.value());
errorAttributes.put("error", errorStatus.getReasonPhrase());
errorAttributes.put("message", this.determineMessage(error));
this.handleException(errorAttributes, this.determineException(error), includeStackTrace);
return errorAttributes;
}1.2).没有模板引擎(模板引擎找不到这个错误页面,比如放在了static文件夹下),在静态资源文件夹下找
1.3).以上都没有错误页面,默认来到springBoot默认的错误提示页面
2).如何定制错误的json数据
2.1).该方式浏览器返回的也是json,没有自适应效果
@ResponseBody
@ExceptionHandler(UserNotExistException.class)
public Map<String,Object> handleException(Exception e){
Map<String,Object> map = new HashMap<>();
map.put("code","user.notexist");
map.put("message",e.getMessage());
return map;
}2.1).如何自适应(浏览器返回页面,其他返回json),需要设置错误状态码,否则解析不到错误状态码,导致200也是返回错误页面
@ExceptionHandler(UserNotExistException.class)
public String handleException(Exception e, HttpServletRequest request){
Map<String,Object> map = new HashMap<>();
//传入我们自己的错误状态码 4xx 5xx
/**
* Integer statusCode = (Integer) request
.getAttribute("javax.servlet.error.status_code");
*/
request.setAttribute("javax.servlet.error.status_code",500);
map.put("code","user.notexist");
map.put("message","用户出错啦");
request.setAttribute("ext",map);
//转发到/error
return "forward:/error";
}2.3).自适应外,我们还有讲定制的数据返回
出现错误后,会来到/error请求,会被BasicErrorController处理,响应出去可以获取的数据是由getErrorAttributes得到的（是AbstractErrorController（ErrorController）规定的方法）；
a、完全来编写一个ErrorController的实现类【或者是编写AbstractErrorController的子类】，放在容器中；
b.、页面上能用的数据，或者是json返回能用的数据都是通过errorAttributes.getErrorAttributes得到；
容器中DefaultErrorAttributes.getErrorAttributes()；默认进行数据处理的；
自定义ErrorAttributes
import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.WebRequest;
import java.util.Map;
//给容器中加入我们自己定义的ErrorAttributes
@Component
public class MyErrorAttributes extends DefaultErrorAttributes {
//返回值的map就是页面和json能获取的所有字段
@Override
public Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace) {
Map<String, Object> map = super.getErrorAttributes(webRequest, includeStackTrace);
map.put("company","123");
//我们的异常处理器携带的数据
Map<String,Object> ext = (Map<String, Object>) webRequest.getAttribute("ext", 0);
map.put("ext",ext);
return map;
}
}最终的效果：响应是自适应的，可以通过定制ErrorAttributes改变需要返回的内容.
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