xml 入门 dtd

xml dtd的格式：

<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT classroom (className,grade,students)>
<!ATTLIST classroom id ID #REQUIRED>
<!ELEMENT className (#PCDATA)>
<!ELEMENT grade (#PCDATA)>
<!ELEMENT students (student+)>
<!ELEMENT student (id,name,age)>
<!ELEMENT id (#PCDATA)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT age (#PCDATA)>

相应的xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE classroom SYSTEM "classroom.dtd">
<!--<!DOCTYPE classroom PUBLIC "http://www.zizhu.com/classroom">-->
<classroom id="p1">
    <className>2010计算机应用技术</className>
    <grade>2010</grade>
    <students>
        <student>
            <id>11</id>
            <name>zizhu8</name>
            <age>20</age>
        </student>
        <student>
             <id>12</id>
            <name>zizhu3</name>
            <age>20</age>
        </student>
    </students>
</classroom>