比如向下面的xml文件中添加新的employee,怎么添加,用什么包?希望有具体代码
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE list SYSTEM "employee.dtd">
<clerklist>
<employee>
   <name>yanzhen</name>
   <number>0001</number>
</employee>
<employee>
   <name>yang</name>
   <number>0002</number>
</employee>
</clerklist>