XML-choice all sequence讲解¶

XML Schema 中 Order 指示器 choice all sequence和 Occurrence 指示器 minOccurs maxOccurs 的用法解释

1 Order 指示器¶

1.1 all¶

<all> 指示器规定子元素可以按照任意顺序出现

1.1.1 myXsd.xsd文件¶

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="www.shuhaiwen.com" targetNamespace="www.shuhaiwen.com" elementFormDefault="qualified">
    <xsd:complexType name="Student">
        <xsd:all minOccurs="1" maxOccurs="1">
            <xsd:element name="Name" type="xsd:string" minOccurs="0" maxOccurs="1"/>
            <xsd:element name="ID" type="xsd:string" minOccurs="1" maxOccurs="1"/>
            <xsd:element name="Hobby" type="xsd:string" minOccurs="0" maxOccurs="1"/>
        </xsd:all>
    </xsd:complexType>
    <xsd:element name="student" type="Student"/>
</xsd:schema>

1.1.2 myXml.xml文件¶

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Name>shu haiwen</Name> 
    <Hobby> football</Hobby>
    <ID>1342566</ID>
</student>

1.1.3 分析¶

<all>元素和子元素中必须设 maxOccrus="1" ，minOccrus="0" 或 "1"
<Hobby>元素可以在<ID>元素之前，元素出现顺序无关

1.1.4 错误示例xml依据上面的xsd代码¶

误用1：子元素出现多次

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Name>shu haiwen</Name> 
    <Hobby>football</Hobby>
    <Hobby>ready</Hobby>
    <ID>1342566</ID>
</student>

error：<Hobby>出现2次

1.2 choice¶

<choice> 指示器规定元素只能出现一次

1.2.1 myXsd.xsd文件¶

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="www.shuhaiwen.com" targetNamespace="www.shuhaiwen.com" elementFormDefault="qualified">
    <xsd:complexType name="Student">
        <xsd:choice minOccurs="1" maxOccurs="1">
            <xsd:element name="Name" type="xsd:string" minOccurs="0" maxOccurs="1"/>
            <xsd:element name="ID" type="xsd:string" minOccurs="1" maxOccurs="1"/>
            <xsd:element name="Hobby" type="xsd:string" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:choice>
    </xsd:complexType>
    <xsd:element name="student" type="Student"/>
</xsd:schema>

1.2.2 myXml.xml文件¶

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Hobby> football</Hobby>
    <Hobby>ready</Hobby>
</student>

1.2.3 分析¶

sequence内元素有且只执行一次，由 minOccurs="1" maxOccurs="1"决定，当minOccurs="0"时，可以不执行，当maxOccurs="2" or 3 or unbounded 时，可以执行指定次数
只能出现 Name ID Hobby 中一中元素类型，可出现次数取决于元素中minOccurs maxOccurs 属性
<student>可以不包含元素，因为 Name 元素的minOccurs="0" ，即当我选择Name元素作为<Student>的子元素时，<Name>可以执行0次,即不执行
当选择 ID 元素作为Student 子元素时，必须执行一次
当选择 Hobby 元素作为Student 子元素时，可执行任意次，对应xml文件中 <Hobby> football</Hobby><Hobby>ready</Hobby>

1.2.4 错误示例xml依据上面的xsd代码¶

误用1：选择多个子元素

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Name>shu haiwen</Name> 
    <ID>1342566</ID>
    <Hobby> football</Hobby>
    <Hobby>ready</Hobby>
</student>

error：<Name> <ID> <Hobby> 只能出现其中一类

误用2：同一元素使用超过 maxOccurs 所规定的数量

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <ID>1342566</ID>
    <ID>5464565</ID>
</student>

error：<ID>只能出现一次

1.3 sequence¶

<sequence> 指示器规定元素按顺序出现
元素是否出现或出现多少次由 minOccurs 和 maxOccurs 属性限制
Example

1.3.1 myXsd.xsd文件¶

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="www.shuhaiwen.com" targetNamespace="www.shuhaiwen.com" elementFormDefault="qualified">
    <xsd:complexType name="Student">
        <xsd:sequence minOccurs="1" maxOccurs="1">
            <xsd:element name="Name" type="xsd:string" minOccurs="0" maxOccurs="1"/>
            <xsd:element name="ID" type="xsd:string" minOccurs="1" maxOccurs="1"/>
            <xsd:element name="Hobby" type="xsd:string" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:sequence>
    </xsd:complexType>
    <xsd:element name="student" type="Student"/>
</xsd:schema>

1.3.2 myXml.xml文件¶

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Name>shu haiwen</Name> 
    <ID>1342566</ID>
    <Hobby> football</Hobby>
    <Hobby>ready</Hobby>
</student>

1.3.3 分析¶

sequence内元素有且只执行一次，由 minOccurs="1" maxOccurs="1"决定，当minOccurs="0"时，可以不执行，当maxOccurs="2" or 3 or unbounded 时，可以执行指定次数
Name 可以执行一次或不执行，对应xml文件中 <Name>shu haiwen</Name> 可以不写或只能出现一次
ID 必须执行一次，必须在 Hobby 之前执行，对应xml文件中 <ID>1342566</ID>
Hobby 可执行任意次，对应xml文件中 <Hobby> football</Hobby><Hobby>ready</Hobby>

1.3.4 错误示例xml依据上面的xsd代码¶

误用1： ID元素不能少

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <Name>shu haiwen</Name>
    <Hobby> football</Hobby>
    <Hobby>ready</Hobby>
</student>

error:缺少<ID>元素

*误用2：元素顺序错误 *

<?xml version="1.0" encoding="UTF-8"?>
<student xmlns="www.shuhaiwen.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="www.shuhaiwen.com myXsd.xsd">
    <ID>1342566</ID>
    <Name>shu haiwen</Name> 
    <Hobby> football</Hobby>
    <Hobby>ready</Hobby>
</student>

error:<ID>元素不能在<Name>元素之前或<Hobby>元素之后