操作XML的一些公共方法，主要判断XML文件是否存在和获取程序集目录的XML文件，若不存在自动插入操作XML的一些公共方法，主要判断XML文件是否存在和获取程序集目录的XML文件，若不存在自动插入节点的公共类-Manipulate XML some common methods, the main judge XML file exists and obtain the assembly directory of XML files, if there is no automatic XML insert some common methods, the main judge XML file exists and obtain the assembly directory of XML files, if there is no automatic insertion node s public class