XML中SystemID和PublicID的区别
http://hi.baidu.com/binboot007/item/1533f91d52113d7c7b5f259c
http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/docbooksys/segmentedhtml/ch08s02.html
http://hi.baidu.com/binboot007/item/1533f91d52113d7c7b5f259c
http://supportweb.cs.bham.ac.uk/documentation/tutorials/docsystem/build/tutorials/docbooksys/segmentedhtml/ch08s02.html