16-1-9 Java Learning Note (2) XML constraints

Definition: In XML technology, you can write a document that constrains the writing of an XML document, which is called an XML constraint.

Function: Constrain the writing of XML documents and validate XML;

Common constraint Techniques: XML DTD (document type definition) documentation type definitions; XML Schema

1 <?XML version= "1.0" encoding= "Utf-8"?>2 <!DOCTYPE Bookshelf SYSTEM "BOOK.DTD">3 <Bookshelf>4     <Book>5         <title>Employment Training Tutorials</title>6         <author>Zhang Xiaoxiang</author>7         <Price>39.00 USD</Price>8     </Book>9     <Book>Ten         <title>Web Development</title> One         <author>Zhang Xiaoxiang</author> A         <Price>29.00 USD</Price> -     </Book> - </Bookshelf>

Book.dtd

<! ELEMENT Bookshelf (book +) > <! ELEMENT Book (title, author, Price) > <! ELEMENT title (#PCDATA) > <! ELEMENT author (#PCDATA) > <! ELEMENT Price (#PCDATA) >

16-1-9 Java Learning Note (2) XML constraints