使用XML命名空间

In an XML document, tags are associated with a namespace. XML namespaces let you refer to more than one set of XML tags in the same XML document. The xmlns property in an MXML tag specifies an XML namespace. To use the default namespace, specify no prefix. To use additional tags, specify a tag prefix and a namespace.

For example, the xmlns property in the following <mx:Application> tag indicates that tags in the MXML namespace use the prefix mx:. The Universal Resource Identifier (URI) for the MXML namespace is http://www.adobe.com/2006/mxml.

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

XML namespaces give you the ability to use custom tags that are not in the MXML namespace. The following example shows an application that contains a custom tag called CustomBox. The namespace value containers.boxes.* indicates that an MXML component called CustomBox is in the containers/boxes directory.

<?xml version="1.0"?>
<!-- mxml/XMLNamespaces.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
    xmlns:MyComps="containers.boxes.*"
>
    <mx:Panel title="My Application" 
        paddingTop="10" 
        paddingBottom="10"
        paddingLeft="10" 
        paddingRight="10"
    >
        <MyComps:CustomBox/>
    </mx:Panel>
</mx:Application>

The containers/boxes directory can be a subdirectory of the directory that contains the application file, or it can be a subdirectory of one of the ActionScript source path directories assigned in the flex-config.xml file. If copies of the same file exist in both places, Flex uses the file in the application file directory. The prefix name is arbitrary, but it must be used as declared.

When using a component contained in a SWC file, the package name and the namespace must match, even though the SWC file is in the same directory as the MXML file that uses it. A SWC file is an archive file for Flex components. SWC files make it easy to exchange components among Flex developers. You exchange only a single file, rather than the MXML or ActionScript files and images, along with other resource files. Also, the SWF file inside a SWC file is compiled, which means that the code is obfuscated from casual view. For more information on SWC files, see Using the Flex Compilers.


    在一份XML文档中，标记都与一个命名空间相关联。 XML命名空间可以让你在同一个XML文档中引用一个或以上的XML标记集合。The xmlns property in an MXML tag specifies an XML namespace.MXML标签中的xmlns属性指定了一个XML命名空间。要使用默认的命名空间，不需要指定前缀。要使用额外的标记需指定一个标记的前缀和相应的命名空间。
    例如，在下面的<mx:Application>标签中表明xmlns了属性，MXML标签的命名空间使用前缀mx:。MXML命名空间的通用资源标识符（URI）是http://www.adobe.com/2006/mxml。

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

    XML命名空间给了你使用MXML命名空间中所没有的自定义标签的能力。下面的例子展示了一个包含一个称为CustomBox的自定义标记的程序。命名空间的值containers.boxes .*表明一个名为CustomBox的MXML组件是在containers/boxes/的目录中。

<?xml version="1.0"?>
<!-- mxml/XMLNamespaces.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
    xmlns:MyComps="containers.boxes.*"
>
    <mx:Panel title="My Application" 
        paddingTop="10" 
        paddingBottom="10"
        paddingLeft="10" 
        paddingRight="10"
    >
        <MyComps:CustomBox/>
    </mx:Panel>
</mx:Application>

    containers/boxes/目录可以包含应用程序文件，子目录，也可以是在Flex-config.xml文件中指定ActionScript的源路径一个目录的子目录。如果同一个文件的副本在两个地方存在，Flex使用在应用程序文件目录中的文件。前缀名称是任意的，但必须作为声明。