Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; 文件提前结束

问题遇到的现象和发生背景

dom4j SAXReader.read无法解析微信公众号post请求中request.getInputstream
报Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; 文件提前结束。异常

问题相关代码，请勿粘贴截图

 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        System.out.println("用户发送post请求");
        ServletInputStream is = request.getInputStream();
        byte[] b=new byte[1024];
        int len;
        StringBuilder sb=new StringBuilder();
        while ((len= is.read(b))!=-1){
            sb.append(new String(b,0,len));
        }
        System.out.println(sb.toString());

         Map<String,String> map=WxService.parseRequest(request.getInputStream());
         if (map==null){
             System.out.println("出现异常");
         }else{
             System.out.println(map);
         }
         
    }

public static Map<String, String> parseRequest(ServletInputStream inputStream) {
        Map<String, String> map = null;
        SAXReader reader = new SAXReader() ;
        try {
            map=new HashMap<>();
            Document document = reader.read(inputStream);
            Element root = document.getRootElement();
            List<Element> eLements =root.elements();
            for (Element eLement : eLements) {
                map.put(eLement.getName(),eLement.getStringValue());
            }
            return map;
        } catch (DocumentException e) {
            e.printStackTrace();
            e.getMessage();
            return null;
        }

    }

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

已解决
java流无法读取两次，所以要把servlet post 中的尝试接受消息的代码注释掉，直接将request.getInputstream传过去就行