在XSLT 1.0中对多个节点进行分组并在公共元素下输出

<?xml version="1.0" encoding="UTF-8"?>
<items>
    <item category="A">
        <name>Item 1</name>
    </item>
    <item category="B">
        <name>Item 2</name>
    </item>
    <item category="A">
        <name>Item 3</name>
    </item>
    <item category="C">
        <name>Item 4</name>
    </item>
    <item category="B">
        <name>Item 5</name>
    </item>
</items>

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <!-- 定义键值 -->
    <xsl:key name="items-by-category" match="item" use="@category"/>

    <!-- 模板匹配根节点 -->
    <xsl:template match="/">
        <categories>
            <!-- 对类别进行排序 -->
            <xsl:for-each select="items/item[generate-id() = generate-id(key('items-by-category', @category)[1])]">
                <xsl:sort select="@category"/>
                <category>
                    <xsl:value-of select="@category"/>
                    <items>
                        <!-- 输出同一类别的所有项目 -->
                        <xsl:for-each select="key('items-by-category', @category)">
                            <item>
                                <xsl:value-of select="name"/>
                            </item>
                        </xsl:for-each>
                    </items>
                </category>
            </xsl:for-each>
        </categories>
    </xsl:template>

</xsl:stylesheet>

<?xml version="1.0" encoding="UTF-8"?>
<categories>
    <category>A</category>
    <items>
        <item>Item 1</item>
        <item>Item 3</item>
    </items>
    <category>B</category>
    <items>
        <item>Item 2</item>
        <item>Item 5</item>
    </items>
    <category>C</category>
    <items>
        <item>Item 4</item>
    </items>
</categories>