什么是复合元素（Complex Elements）？
A complex element is an XML element that contains other elements and/or attributes.
复合元素（Complex Elements）是含有其他元素和/或属性的XML元素
There are four kinds of complex elements:
有四种复合元素（Complex Elements）：
- empty elements
空元素 - elements that contain only other elements
只含有其他元素的元素 - elements that contain only text
只含有文本的元素 - elements that contain both other elements and text
含有文本和其他元素的元素
Note: Each of these elements may contain attributes as well!
注意：这些元素中的每一个也许还含有属性!
Examples of Complex Elements
复合元素（Complex Elements）的例子
A complex XML element, "product", which is empty:
一个空的复合XML元素"product"：
<product pid="1345"/> |
A complex XML element, "employee", which contains only other elements:
只含有其他元素的复合XML元素, "employee"
<employee> <firstname>John</firstname> <lastname>Smith</lastname> </employee> |
A complex XML element, "food", which contains only text:
只含有文本的复合XML元素， "food"：
<food type="dessert">Ice cream</food> |
A complex XML element, "description", which contains both elements and text:
含有元素和文本的复合XML元素, "description"：
<description> It happened on <date lang="norwegian">03.03.99</date> .... </description> |
How to Define a Complex Element
怎样定义一个复合元素（Complex Elements）？
Look at this complex XML element, "employee", which contains only other elements:
看这个只含有其他元素的复合XML元素，"employee"：
<employee> <firstname>John</firstname> <lastname>Smith</lastname> </employee> |
We can define a complex element in an XML Schema two different ways:
我们有两种方法可以在一篇XML Schema里定义一个复合元素（Complex Elements）：
1. The "employee" element can be declared directly by naming the element, like this:
1. "employee"元素可以直接通过命名元素的方式被声明，像这样：
<xs:element name="employee">
<xs:complexType>
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
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If you use the method described above, only the "employee" element can use the specified complex type. Note that the child elements, "firstname" and "lastname", are surrounded by the <sequence> indicator. This means that the child elements must appear in the same order as they are declared. You will learn more about indicators in the XSD Indicators chapter.
如果你用了上面的方法，那么只有"employee"元素才可以用指定的复合类型。注意子元
素"firstname" 和
"lastname",它们是被包围在<sequence>“指示器”元素里的。这意味着子元素必须以它们被声明的顺序出现。在XSD指示器
这章里你可以学到关于指示器更多内容。
2. The "employee" element can have a type attribute that refers to the name of the complex type to use:
2. "employee"元素可以有个类型属性，其所指的是要用的复合类型的名称
<xs:element name="employee" type="personinfo"/> <xs:complexType name="personinfo">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
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If you use the method described above, several elements can refer to the same complex type, like this:
如果你用上述方法，几个元素指的可以是相同的复合类型，就像这样：
<xs:element name="employee" type="personinfo"/> <xs:element name="student" type="personinfo"/> <xs:element name="member" type="personinfo"/> <xs:complexType name="personinfo">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
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You can also base a complex element on an existing complex element and add some elements, like this:
你也可以在现存的复合元素（Complex Elements）上再加上一个复合元素（Complex Elements），并添加一些元素，就像这样：
<xs:element name="employee" type="fullpersoninfo"/> <xs:complexType name="personinfo">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="fullpersoninfo">
<xs:complexContent>
<xs:extension base="personinfo">
<xs:sequence>
<xs:element name="address" type="xs:string"/>
<xs:element name="city" type="xs:string"/>
<xs:element name="country" type="xs:string"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
|
An empty complex element cannot have contents, only attributes.
一个空的复合元素不能含有内容，只能含有属性。
Complex Empty Elements
复合空元素（Complex Empty Elements）
An empty XML element:
一个空的XML元素：
<product prodid="1345" /> |
The "product" element above has no content at all. To define a type with no content, we must define a type that allows only elements in its content, but we do not actually declare any elements, like this:
上述"product"元素完全不含内容。为定义不含内容的类型，我们必须定义一个内容中只允许出现元素的类型，但我们不需要声明任何元素，就像这样：
<xs:element name="product">
<xs:complexType>
<xs:complexContent>
<xs:restriction base="xs:integer">
<xs:attribute name="prodid" type="xs:positiveInteger"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:element>
|
In the example above, we define a complex type with a complex content. The complexContent element signals that we intend to restrict or extend the content model of a complex type, and the restriction of integer declares one attribute but does not introduce any element content.
上述例子中，我们定义了一个有复合内容的复合类型。复合内容的元素表示了我们想要约束或扩充的复合类型的内容模式。对整数的约束声明了一个属性，但并没有介绍任何元素内容。
However, it is possible to declare the "product" element more compactly, like this:
但是，可以更加简洁地声明"product"元素，就像这样：
<xs:element name="product">
<xs:complexType>
<xs:attribute name="prodid" type="xs:positiveInteger"/>
</xs:complexType>
</xs:element>
|
Or you can give the complexType element a name, and let the "product" element have a type attribute that refers to the name of the complexType (if you use this method, several elements can refer to the same complex type):
或者你可以给complexType元素起个名称，并让"product"元素有个类型属性，而且类型属性引用的是complexType的名称（如果你用这个方法，几个元素可以引用相同的复合类型）：
<xs:element name="product" type="prodtype"/> <xs:complexType name="prodtype"> <xs:attribute name="prodid" type="xs:positiveInteger"/> </xs:complexType> |
An "elements-only" complex type contains an element that contains only other elements.
“只有元素（Elements-only）”复合类型含有一个只包含其他元素的元素
Complex Types Containing Elements Only
复合类型只含有元素
An XML element, "person", that contains only other elements:
一个XML元素, "person",只含有其他元素：
<person> <firstname>John</firstname> <lastname>Smith</lastname> </person> |
You can define the "person" element in a schema, like this:
你可以在一篇schema里定义"person"元素，就像这样
<xs:element name="person">
<xs:complexType>
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
</xs:element>
|
Notice the <xs:sequence> tag. It means that the elements defined ("firstname" and "lastname") must appear in that order inside a "person" element.
注意<xs:sequence>标签。这表示所定义的元素("firstname" 和 "lastname")必须在"person"元素里以那样的次序出现。
Or you can give the complexType element a name, and let the "person"
element have a type attribute that refers to the name of the complexType
(if you use this method, several elements can refer to the same complex
type):
或者你可以给complexType元素取个名字，让"person"元素有个类型属性，这个类型属性的名字可以参考使用complexType元素的名字（如果你用这个方法，几个元素可以同时参考使用相同的复合类型）。
<xs:element name="person" type="persontype"/> <xs:complexType name="persontype">
<xs:sequence>
<xs:element name="firstname" type="xs:string"/>
<xs:element name="lastname" type="xs:string"/>
</xs:sequence>
</xs:complexType>
|
A complex text-only element can contain text and attributes.
一个复合只含文本元素（Complex Text-Only Elements）可以含有文本和属性。
Complex Text-Only Elements
复合只含文本元素（Complex Text-Only Elements）
This type contains only simple content (text and attributes),
therefore we add a simpleContent element around the content. When using
simple content, you must define an extension OR a restriction within the
simpleContent element, like this:
这种类型只含有简单内容（文本和属性），因此我们在内容周围添加一个simpleContent元素，当用到简单内容时，你必须在simpleContent元素里定义一个扩展或约束，就像这样：
<xs:element name="somename">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="basetype">
....
....
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
OR <xs:element name="somename">
<xs:complexType>
<xs:simpleContent>
<xs:restriction base="basetype">
....
....
</xs:restriction>
</xs:simpleContent>
</xs:complexType>
</xs:element>
|
Tip: Use the extension/restriction element to expand or to limit the base simple type for the element.
提示：用extension/restriction元素扩展或限制元素的基本简单类型（base simple type）。
Here is an example of an XML element, "shoesize", that contains text-only:
这儿是只含有文本的一个XML元素, "shoesize"：
<shoesize country="france">35</shoesize> |
The following example declares a complexType, "shoesize". The content is defined as an integer value, and the "shoesize" element also contains an attribute named "country":
下面的例子声明了一个复合类型，"shoesize"元素。内容定义为整数值，"shoesize"元件含有名为"country"的属性。
<xs:element name="shoesize">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:integer">
<xs:attribute name="country" type="xs:string" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
|
We could also give the complexType element a name, and let the "shoesize" element have a type attribute that refers to the name of the complexType (if you use this method, several elements can refer to the same complex type):
我们可以给complexType元件起个名字，让"shoesize"元件有种类属性，种类属性的名字就是complexType元件的名字。（如果你用这种方法，几个元素指的可以是相同的复合类型）
<xs:element name="shoesize" type="shoetype"/> <xs:complexType name="shoetype">
<xs:simpleContent>
<xs:extension base="xs:integer">
<xs:attribute name="country" type="xs:string" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
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A mixed complex type element can contain attributes, elements, and text.
混合内容的复合类型元素（XSD Complex Types Element With Mixed Content ）可以含有属性，元素，和文本。
Complex Types with Mixed Content
混合内容的复合类型
An XML element, "letter", that contains both text and other elements:
一个XML元素，"letter",既含有文本又含有其他元素：
<letter> Dear Mr.<name>John Smith</name>. Your order <orderid>1032</orderid> will be shipped on <shipdate>2001-07-13</shipdate>. </letter> |
The following schema declares the "letter" element:
下面的XML公式声明了"letter"元素：
<xs:element name="letter">
<xs:complexType mixed="true">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="orderid" type="xs:positiveInteger"/>
<xs:element name="shipdate" type="xs:date"/>
</xs:sequence>
</xs:complexType>
</xs:element>
|
Note: To enable character data to appear between the child-elements of "letter", the mixed attribute must be set to "true". The <xs:sequence> tag means that the elements defined (name, orderid and shipdate) must appear in that order inside a "letter" element.
注意：为了使字符数据能出现在"letter"子元件之间，mixed属性必须设置为"true"。<xs:sequence>标签指出了已定义的元素(name, orderid 和shipdate)在"letter"元素里必须以指定的顺序出现
We could also give the complexType element a name, and let the
"letter" element have a type attribute that refers to the name of the
complexType (if you use this method, several elements can refer to the
same complex type):
我们可以给这个complexType元素一个名称，并且让"letter"元素有一个引用了complexType的名称的种类属性（如果你用了这个方法，几个元素可以同时使用相同的复合类型）：
<xs:element name="letter" type="lettertype"/> <xs:complexType name="lettertype" mixed="true">
<xs:sequence>
<xs:element name="name" type="xs:string"/>
<xs:element name="orderid" type="xs:positiveInteger"/>
<xs:element name="shipdate" type="xs:date"/>
</xs:sequence>
</xs:complexType>
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