xml schema 中如何定义类似Map的结构

利用xs：unique关键字。在xs:element里添加unique节点，任意命名，然后用xs:selector来选择需要唯一的域， xs:field 里指定特定的字段。

例如：定义所有Item里的Key为唯一，

< xs:complexType >

< xs:sequence minOccurs =" 0 " maxOccurs =" unbounded ">

< xs:element name =" Item " type =" IdentifiersWithSourceItemType ">

</ xs:element >

</ xs:sequence >

</ xs:complexType >

< xs:unique name =" KeyUnique ">

< xs:selector xpath =" .//Key "/>

< xs:field xpath =" .//NamespaceID "/>

</ xs:unique >

< xs:unique name =" KeyUnique2 ">

< xs:selector xpath =" .//Key "/>

< xs:field xpath =" .//UniversalIDType "/>

< xs:field xpath =" .//Universal/UniversalID "/>

</ xs:unique >