https://zhuanlan.zhihu.com/p/437170303
解决HttpServletRequest 流数据不可重复读 - Fururur - 博客园

import org.springframework.web.util.ContentCachingRequestWrapper;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

/**
 * @author husui
 * @date 2025/2/11
 */
@WebFilter(filterName = "CachingContentFilter", urlPatterns = "/*")
public class CachingContentFilter implements Filter {

    private static final String FORM_CONTENT_TYPE = "multipart/form-data";


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        String contentType = request.getContentType();
        // 遇到 multipart/form-data 数据时，不需要 wrapper，会直接通过 MultipartResolver 将参数封装成 Map
        if (request instanceof HttpServletRequest && contentType != null && !contentType.contains(FORM_CONTENT_TYPE)) {
            // 使用 ContentCachingRequestWrapper 包装请求，缓存请求体
            ContentCachingRequestWrapper wrappedRequest = new ContentCachingRequestWrapper((HttpServletRequest) request);
            // 继续执行过滤链
            chain.doFilter(wrappedRequest, response);
        } else {
            // 继续过滤链
            chain.doFilter(request, response);
        }
    }

    @Override
    public void destroy() {

    }
}

感悟：没事别自己造轮子。更糟的是照抄别人造的轮子还不知道为啥。