Detailed introduction to code examples of namespaces in XML

XMLNamespaceprovides a way to avoid naming elements Conflicting methods.

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Naming conflict
Because the elements used in XML documents are not fixed, it may happen that two different XML documents use the same name to describe different types of elements, and this situation often leads to naming conflicts. Please see the following two. Example

This XML document carries fruit information in the table element:

This XML document carries table information (furniture, not edible) in the table element:

If the above two XML document fragments happen to be used together, there will be a naming conflict because both fragments contain

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Use prefixes to resolve naming conflicts
The following XML document carries information in the table element:

The following XML document carries information about the furniture table:

Now it has There is no element naming conflict problem, because the two documents use different prefixes for their respective table elements, which are ( and ) # in the two documents.

The following XML document carries information in the table element:

attributeto associate the elements with different namespaces

Namespace attributes are generally placed at the start tag of an element , its usage syntax is as follows:

W3CNaming specification statement The namespace itself is a Uniform Resource Identifier, UniformResourceIdentifier (URI).

Uniform Resource Identifier (A Uniform Resource Identifier (URI)) is a
stringthat identifies a network resource. The most common URI should be the Uniform Resource Locator (URL). A URL is used to identify the address of a network host. On the other hand, another less commonly used URI is the Universal Resource Name (URN). In our case, URLs are generally used.

Definition A default XML namespace eliminates the need for prefixes in the opening tags of child elements. His syntax is as follows:

file start When using XSL, you will find that namespaces are used so frequently. XSL style sheets are mainly used to convert XML documents into a format similar to HTML files.

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elements, and the definitions of these two table elements. The contents are different from each other.##By using the prefix, we create two different table elements------------------------ -------------------------------------------------- -----Use namespace The following XML document carries information about the furniture table: In addition to using prefixes in the above two examples, both table elements use the xmlns--. -------------------------------------------------- ----------------------------Namespace attributes In the above example, the namespace defines an Internet address: When we use a namespace at the start tag of an element, all child elements of the element will be related to the same namespace through a prefix.Note: The network address used to identify the namespace is not called by the XML parser. The XML parser does not need to find information from this network address. The role of the network address is only to give the namespace a unique Name, so this network address can also be virtual. However, many companies often treat this network address value like a real Web page. This address contains more detailed information about the current namespace.Uniform Resource IdentifierSince the previous example used the URL address to identify the namespace, we can be sure that this namespace is unique.-------------------------------------------------- ------------------------------------Default namespace The following XML document contains fruit information in the table element:

Apples

Bananas

African Coffee Table80120

     
 
 
Title
 
Artist