如何解决XML文件中的警告提示“No grammar constraints (DTD or XML Schema) referenced in the document.”

解决方法：加上 <!DOCTYPE xml>

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE xml>

<ROOT>

 <goods>

  <isin>SN100001</isin>

  <quantity>1100</quantity>

  <price>200.20</price>

  <customer>张三</customer>

 </goods>

</ROOT>