I need a hint regarding a quick finding of specific nodes within the XML and removing the entire parent node (with children) if some of the values don't match the input parameters.

我需要一个关于在XML中快速查找特定节点的提示，如果某些值与输入参数不匹配，则删除整个父节点（带子节点）。

Example, having the XML as shown below:

示例，具有如下所示的XML：

<someparent attr="123" filters="+F1">
    <filter id="F1">
        <width>
            <paper size="a4" val="10" />
            <paper size="a3" val="12" />
        </width>
        <height>
            <paper size="a4" val="10" />
            <paper size="a3" val="12" />
        </height>
    </filter>
</someparent>

I should apply some rules:

我应该应用一些规则：

• like if filters has a value starting with + (+F1) then if parameters match sizes and values, like: a4/10 or a3/12 should not remove the someparent node - any other size should causing the node removal


• if filters has a value starting with - (-F1) then if parameters matching sizes and values, like: a4/10 or a3/12 should remove the someparent node - any other size should leave the node intact

However, I think that may be irrelevant at this point. The most important is quickly finding the filter nodes and removing parent nodes if needed.

然而，我认为在这一点上，这可能无关紧要。最重要的是快速找到过滤器节点，并在需要时删除父节点。

Extra notes:

额外注意事项：

• XPath is way too slow - literally unacceptable, Iterating over every single node is relatively quick - it's currently working like that - however, I'd like to improve that. I'm pretty sure it can be improved.


• it may happen that filter node(s) does not exist in the file at all

My plan is to create some prototypes, however... I'd appreciate any hints that may help me.

我的计划是创建一些原型，然而。。。如果能给我任何帮助，我将不胜感激。

In general the different built-in parsers are SAX, StAX and DOM (https://rdayala.wordpress.com/dom-vs-sax-parsers/).

通常，不同的内置解析器是SAX、StAX和DOM(https://rdayala.wordpress.com/dom-vs-sax-parsers/)。

• DOM is the slow one (load everything into memory) and is used with XPath.


• SAX is a pain to use.


• StAX actually has 2 APIs:
  
  
  
  • the iterator API, e.g. XMLEventReader (easier)
  
  
  • the cursor API, e.g. XMLStreamReader (more efficient)
  
  
  
  

You could also try using XSLT, but the built-in one isn't necessarily the most high performing and you may need to pay for a premium one or to use all its features (streamed processing):

https://docs.oracle.com/javase/tutorial/jaxp/xslt/transformingXML.html

您也可以尝试使用XSLT，但内置的XSLT不一定是性能最高的，您可能需要付费购买高级XSLT或使用其所有功能（流式处理）：https://docs.oracle.com/javase/tutorial/jaxp/xslt/transformingXML.html

This xslt 1.0 will do your job:

此xslt 1.0将完成您的工作：

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
  <xsl:strip-space elements="*"/>
  
  <!-- identity transform -->
  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>
  
  <xsl:template match="someparent[@filters='+F1'][not(filter/width[paper[concat(@size,'/',@val)='a4/10'] and paper[concat(@size,'/',@val)='a3/12']])]"/>
  
  <xsl:template match="someparent[@filters='-F1'][(filter/width[paper[concat(@size,'/',@val)='a4/10'] and paper[concat(@size,'/',@val)='a3/12']])]"/>
  
  
</xsl:stylesheet>

Obviously, you need to parse the whole document, and the fastest way way to arrive at a solution is to not include the "filtered out" elements in the document building process. Both DOM4J and JDOM are good alternatives for this, since they allow custom document builders that can defer or allow the tree construction based on previously obtained conditions. SAX/StAX is of course also an alternative, but at a lower level and require more infrastructure code to get a result.

显然，您需要解析整个文档，而获得解决方案的最快方法是在文档构建过程中不包含“过滤掉的”元素。DOM4J和JDOM都是很好的替代方案，因为它们允许自定义文档生成器根据之前获得的条件推迟或允许树构建。SAX/StAX当然也是一种选择，但级别较低，需要更多的基础结构代码才能得到结果。

Search this site for DOM4J/JDOM and builder, I may already have given the answer ;)

在这个网站上搜索DOM4J/JDOM和建设者，我可能已经给出了答案；）