XML实体中不允许出现"&","<",">"等特殊字符,否则XML语法检查时将出错,如果出现这些字符,则将自动转换为"&","<",">",所以在读取XML文件的时候需要对这些特定的字符进行相应的处理;
附:XML的转义字符;
& & < < > > " " '
