错误：元素“xsd：schema”的前缀“xsd”未绑定

Question

我对XML非常陌生，现在已准备好Ineasysteps。 我一直从解析器得到相同的问题，他说

5:The prefix "xsd" for element "xsd:schema" is not bound.

这是的hello.xml：

<?xml version = "1.0" encoding = "UTF-8" ?> 

<!-- XML in easy steps - Page 82. --> 

<doc xmlns:xsi= 
"http://www.w3.org/2001/XMLSchema-instance" 
xsi:noNamespaceSchemaLocation = "hello.xsd" > 

<msg>Hello World</msg> 

</doc> 

这里是hello.xsd DOC

<?xml version="1.0" encoding = "UTF-8" ?> 

<!-- XML in easy steps - Page 84. --> 

<xsd:schema> 

<!-- DECLARE ELEMENTS. --> 

<!-- Simple types. --> 
<xsd:element name="msg" type="xsd:string"/> 

<!-- Complex types. --> 
<xsd:element name="doc" type="docType"/> 

<!-- DEFINE STRUCTURE. --> 

<xsd:complexType name="docType"> 
<xsd:sequence> 
    <xsd:element ref="msg"/> 
</xsd:sequence> 
</xsd:complexType 

Answer 1

命名空间前缀。因为在使用前必须定义xsd。这甚至适用于通常用于XML模式组件（XSD）的着名的xsd（或xs）前缀。

要消除错误，通过添加

xmlns:xsd="http://www.w3.org/2001/XMLSchema" 

到xsd:schema根元素这样定义xsd命名空间前缀：

<?xml version="1.0" encoding = "UTF-8" ?> 
<!-- XML in easy steps - Page 84. --> 
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> 

    <!-- DECLARE ELEMENTS. --> 

    <!-- Simple types. --> 
    <xsd:element name="msg" type="xsd:string"/> 

    <!-- Complex types. --> 
    <xsd:element name="doc" type="docType"/> 

    <!-- DEFINE STRUCTURE. --> 

    <xsd:complexType name="docType"> 
    <xsd:sequence> 
     <xsd:element ref="msg"/> 
    </xsd:sequence> 
    </xsd:complexType> 
</xsd:schema>