SpringBoot动态加载静态资源

Spring Boot 静态资源默认是放在 `/static`，`/public`，`/resources`，`/META-INF/resources` 目录下的，这些资源在应用启动时会被加载到内存中供访问。如果需要动态加载静态资源，可以使用 `ResourceHttpRequestHandler`。

下面是一个简单示例：

1. 创建 `DynamicResourceController` 控制器类，该类负责动态加载静态资源：

@Controller
public class DynamicResourceController {
    @Autowired
    private ResourceLoader resourceLoader;

    @RequestMapping("/dynamic/**")
    public ResponseEntity<Resource> getDynamicResource(HttpServletRequest request) throws IOException {
        String path = (String) request.getAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
        String bestMatchingPattern = (String) request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
        AntPathMatcher apm = new AntPathMatcher();
        String relativePath = apm.extractPathWithinPattern(bestMatchingPattern, path);
        Resource resource = resourceLoader.getResource("classpath:dynamic/" + relativePath);
        if (!resource.exists()) {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
        return ResponseEntity.ok(resource);
    }
}

2. 在 `application.properties` 中配置静态资源路径：

spring.mvc.static-path-pattern=/static/**

3. 在 `WebMvcConfigurer` 中注册 `ResourceHttpRequestHandler`：

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**")
                .addResourceLocations("classpath:/static/");
        registry.addResourceHandler("/dynamic/**")
                .addResourceLocations("classpath:/dynamic/")
                .resourceChain(false)
                .addResolver(new PathResourceResolver() {
                    @Override
                    protected Resource getResource(String resourcePath, Resource location) throws IOException {
                        Resource requestedResource = location.createRelative(resourcePath);
                        if (requestedResource.exists() && requestedResource.isReadable()) {
                            return requestedResource;
                        } else if (resourcePath.contains(".")) {
                            String pathPrefix = resourcePath.substring(0, resourcePath.lastIndexOf("."));
                            String pathSuffix = resourcePath.substring(resourcePath.lastIndexOf("."));
                            Resource indexResource = location.createRelative(pathPrefix + ".html");
                            if (indexResource.exists() && indexResource.isReadable()) {
                                return indexResource;
                            }
                        }
                        return new ClassPathResource("/dynamic/index.html");
                    }
                });
    }
}

4. 在 `/dynamic` 目录下创建静态资源文件，例如 `/dynamic/index.html`。

5. 启动应用，访问 `http://localhost:8080/dynamic/index.html` 即可动态加载静态资源。

以上就是使用 `ResourceHttpRequestHandler` 实现动态加载静态资源的方法。