怎样写XSD文件1

xsd页面

xml约束条件
根元素<pets>
子元素是<cat><dog>,序列出现,最少出现2次,最大不限制.

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="cat" type="xs:string"/>
<xs:element name="dog" type="xs:string"/>
<xs:complexType name="myType">
<xs:sequence minOccurs="2" maxOccurs="unbounded">
<xs:element ref="cat"/>
<xs:element ref="dog"/>
</xs:sequence>
</xs:complexType>
<xs:element name="pets" type="myType"/>
</xs:schema>


xml页面

<?xml version="1.0" encoding="UTF-8"?>
<pets xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="test1.xsd">
<cat>hello</cat>
<dog>world</dog>
<cat>hello</cat>
<dog>world</dog>
</pets>