根据元素属性在命令行中拆分xml文件

Question

我拥有具有不同节点和属性的巨大xml文件。我用grep -c来计算具有特定类型的产品。这里是我迄今所做的：

grep -c "</products>" products.xml // output : 200023 

grep -c '<product type="cloths"' products.xml // output : 8039 

所以我需要提取与型布料如在new.xml文件树中的所有产品无所有其他属性，这样我可以导入new.xml文件导入数据库：

<?xml version="1.0"?> 
<!DOCTYPE catalog SYSTEM "catalog.dtd"> 
<catalog> 
    <product type="cloths" product_image="cardigan.jpg"> 
     <catalog_item gender="Men's"> 
     <item_number>QWZ5671</item_number> 
     <price>39.95</price> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     </catalog_item> 
     <catalog_item gender="Women's"> 
     <item_number>RRX9856</item_number> 
     <price>42.50</price> 
     <size description="Small"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Extra Large"> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     </catalog_item> 
    </product> 
</catalog> 

Answer 1

从显示0​​样品和应用的问题命令行标记，它看起来像你想要一个纯命令行的解决方案。一种选择是使用xmllint来运行XPath查询，该查询只选择类型为“布料”的产品。

> xmllint --xpath /catalog/product[@type=\"cloths\"] products.xml 
<product type="cloths" product_image="cardigan.jpg"> 
     <catalog_item gender="Men's"> 
     <item_number>QWZ5671</item_number> 
     <price>39.95</price> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     </catalog_item> 
     <catalog_item gender="Women's"> 
     <item_number>RRX9856</item_number> 
     <price>42.50</price> 
     <size description="Small"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
     </size> 
     <size description="Medium"> 
      <color_swatch image="red_cardigan.jpg">Red</color_swatch> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Large"> 
      <color_swatch image="navy_cardigan.jpg">Navy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     <size description="Extra Large"> 
      <color_swatch image="burgundy_cardigan.jpg">Burgundy</color_swatch> 
      <color_swatch image="black_cardigan.jpg">Black</color_swatch> 
     </size> 
     </catalog_item> 
    </product> 

但请注意，这不会产生格式良好的XML文档。它只是一个包含XPath查询所选内容的节点集。但是，您可以将其包装在一些额外的脚本中以生成完整的XML文档。

printf '<?xml version="1.0"?>\n' > cloths.xml 
printf '<!DOCTYPE catalog SYSTEM "catalog.dtd">\n' >> cloths.xml 
printf '<catalog>\n' >> cloths.xml 
xmllint --xpath /catalog/product[@type=\"cloths\"] products.xml >> cloths.xml 
printf '\n</catalog>\n' >> cloths.xml 

我省略了这些命令之间的错误检查以简化代码示例。

您还提到输入XML文件很大。取决于多大，这种方法在内存消耗方面可能无法很好地扩展。如果这是一个问题，那么您可能需要采取更多的流式处理方法来解决问题，一次读取输入文档的一小部分并逐步处理。这可能会超出命令行领域和定制编码领域。流式XML API的一个例子是Java中的StAX。这是一个tutorial。