code: public void enableDTD(boolean enable) {
          //允许DTD会有XXE漏洞，关于XXE漏洞：https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet
          if (enable) {
              //不允许DTD
              setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
              setFeature("http://xml.org/sax/features/external-general-entities", false);
              setFeature("http://xml.org/sax/features/external-parameter-entities", false);
          } else {
              setFeature("http://apache.org/xml/features/disallow-doctype-decl", false);
              setFeature("http://xml.org/sax/features/external-general-entities", true);
              setFeature("http://xml.org/sax/features/external-parameter-entities", true);
          }
      }
docs: 设置DTD支持
  
  @param enable true表示支持DTD，false表示不支持