Spring 3.0 HEAD 请求 是一个非常有用的功能，它允许在 HTTP 请求中使用 HEAD 方法来获取资源的元数据，而无需获取资源的实际内容。这对于快速检查资源的存在性、获取资源的大小或者检查资源的最后修改日期等情况非常有帮助。

java
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = restTemplate.headForHeaders("https://example.com/resource");
System.out.println("Content-Length: " + headers.getContentLength());
System.out.println("Last-Modified: " + headers.getLastModified());

java
@Controller
public class ImageController {
    @GetMapping("/image/{imageName}")
    public String getImageMetadata(@PathVariable String imageName, Model model) {
        RestTemplate restTemplate = new RestTemplate();
        HttpHeaders headers = restTemplate.headForHeaders("https://example.com/images/" + imageName);
        model.addAttribute("imageName", imageName);
        model.addAttribute("contentLength", headers.getContentLength());
        model.addAttribute("lastModified", headers.getLastModified());
        return "image";
    }
}

html
    
    
Image Metadata
    
Image Name: 
    
Content Length: 
    
Last Modified: