registry.addViewController("/").setViewName("doc.html");

 /**
     * 方案一： 默认访问根路径跳转 doc.html页面 （swagger文档页面）
     * 方案二： 访问根路径改成跳转 index.html页面 （简化部署方案： 可以把前端打包直接放到项目的 webapp，上面的配置）
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        //registry.addViewController("/").setViewName("doc.html");
       handleMappingViewControllers(registry);
    }

    @Bean
    @MvcMapping
    public Map defaultMvcMapping() {
        Map result = new HashMap();
        MvcDef root = MvcDef.create("/","doc.html");
        result.put(root.getPath(),root);
        return result;
    }

    private void handleMappingViewControllers(ViewControllerRegistry registry) {

        ApplicationContext context = SpringContextUtils.getApplicationContext();

        Map<String, Object> beanMaps = context.getBeansWithAnnotation(MvcMapping.class);

        if (null == beanMaps) {
            return;
        }
        HashMap<String,MvcDef> mvc = new HashMap();
        for (Object val : beanMaps.values()) {
            if (!(val instanceof Map)) {continue;}
            Map mvcMaps = (Map)val;
            for (Object def : mvcMaps.values()) {
                if (def instanceof MvcDef) {
                    handleOverrideMapping(mvc, (MvcDef)def);
                }
            }
        }

        for (MvcDef def : mvc.values()) {
           registry.addViewController(def.getPath()).setViewName(def.getView());
        }
    }
    private void handleOverrideMapping(HashMap mvc,MvcDef def){
        Object val = mvc.get(def.getPath());
        if (null == val){
            mvc.put(def.getPath(),def);
            return ;
        }
        MvcDef existDef = (MvcDef)val;
        if (existDef.getPriority()< def.getPriority()){
            mvc.put(def.getPath(),def);
        }
    }

    @Bean
    @MvcMapping
    public Map indexMvcMapping() {
        Map result = new HashMap();
        MvcDef root = MvcDef.create("/","index.html",999);
        result.put(root.getPath(),root);
        return result;
    }