14、SpringBoot-CRUD错误处理机制（1）

一、springboot默认的处理机制

1.浏览器返回一个错误的页面

默认处理错误：返回一个错误的页面：

包括错误类型、时间......

2.其他客户端访问

默认响应一个json数据

原理：

错误自动配置的类：ErrorMvcAutoConfiguration.java

默认配置：

@Bean

@ConditionalOnMissingBean(

    value = {ErrorAttributes.class},

    search = SearchStrategy.CURRENT

)

public DefaultErrorAttributes errorAttributes() {

    return new DefaultErrorAttributes(this.serverProperties.getError().isIncludeException());

}

@Bean

@ConditionalOnMissingBean(

    value = {ErrorController.class},

    search = SearchStrategy.CURRENT

)

public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) {

    return new BasicErrorController(errorAttributes, this.serverProperties.getError(), this.errorViewResolvers);

}

@Bean

public ErrorMvcAutoConfiguration.ErrorPageCustomizer errorPageCustomizer() {

    return new ErrorMvcAutoConfiguration.ErrorPageCustomizer(this.serverProperties, this.dispatcherServletPath);

}

@Bean

@ConditionalOnBean({DispatcherServlet.class})

@ConditionalOnMissingBean

public DefaultErrorViewResolver conventionErrorViewResolver() {

    return new DefaultErrorViewResolver(this.applicationContext, this.resourceProperties);

}

1、DefaultErrorAttributes：

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;

}

2、BasicErrorController：处理默认/error请求

@Controller

@RequestMapping({"${server.error.path:${error.path:/error}}"})

public class BasicErrorController extends AbstractErrorController {

@RequestMapping(

    produces = {"text/html"}//产生html类型数据，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 = 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，包含页面地址和页面内容

    ModelAndView modelAndView = this.resolveErrorView(request, response, status, model);

    return modelAndView != null ? modelAndView : new ModelAndView("error", model);

}

@RequestMapping   //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 = this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.ALL));

    HttpStatus status = this.getStatus(request);

    return new ResponseEntity(body, status);

}

...

}

3、ErrorPageCustomizer：

public class ErrorProperties {

@Value("${error.path:/error}")

private String path = "/error";

public String getPath() {

    return this.path;

}

...

}

4、DefaultErrorViewResolver：

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会找到某个页面   error/404

    String errorViewName = "error/" + viewName;

    //模板引擎可以解析页面地址就使用模板引擎解析

    TemplateAvailabilityProvider provider =

                this.templateAvailabilityProviders.getProvider(errorViewName, this.applicationContext);

    ///模板引擎不可用，就在静态资源文件夹下找errorViewName对应的页面

    return provider != null ? new ModelAndView(errorViewName, model) :

 this.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进行处理

1）响应页面（resolveErrorView方法）去那个页面是由DefaultErrorViewResolver解析得到的

protected ModelAndView resolveErrorView(HttpServletRequest request,

HttpServletResponse response, HttpStatus status, Map<String, Object> model) {

    //所有的ErrorViewResolver得到ModelAndView

    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;

}

巴特西

14、SpringBoot-CRUD错误处理机制（1）

一、springboot默认的处理机制

原理：

步骤：

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