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1.参考

参考文章：# SpringMVC自定义兼容性HandlerMapping

2.简介

实现对静态资源路径的动态修改，达到控制前端资源切换的效果。
有两种实现方式
. A：基于自定义兼容性HandlerMapping
. B：更新原有映射

3.环境

1. jdk11
2. springboot:2.2.8.RELEASE

4.代码

4.1 基于自定义兼容性HandlerMapping

参考文章：# SpringMVC自定义兼容性HandlerMapping

4.2 更新原有映射

原理

1. WebMvcConfigurationSupport 注册 各个类型的HandlerMapping

2. 其中注册的 resourceHandlerMapping 负责映射静态资源

3. 通过修改其原有的映射信息达到控制更新

image.png

默认映射

@Configuration
public class WebConfiguration implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        String req = "/html/**";
        String path = "file:C:/html/";
        registry.addResourceHandler(req).addResourceLocations(path);
    }

}

修改映射

    public static void main(String[] args) throws Exception {
        ApplicationContext app = SpringApplication.run(App.class, args);
        update(app,"/html/**","file:D:/html/");
    }

    public static void update(ApplicationContext ctx, String url, String resource) {
        SimpleUrlHandlerMapping mapping = (SimpleUrlHandlerMapping) ctx.getBean("resourceHandlerMapping");
        ResourceHttpRequestHandler handler = (ResourceHttpRequestHandler) mapping.getUrlMap().get(url);
        if (handler != null) {
            handler.setLocationValues(List.of(resource));
            handler.getLocations().clear();
            handler.getResourceResolvers().clear();
            try {
                handler.afterPropertiesSet();
            } catch (Throwable ex) {
                throw new BeanInitializationException("Failed to init ResourceHttpRequestHandler", ex);
            }
        }
    }