XmlReader 不断读取 [英] XmlReader read continually

问题描述

我有一个非常大的 xml 文件.这是 xml 格式的简化版本.

I have a very large xml file. This is the simplified version of xml format.

<?xml version='1.0' encoding='UTF-8'?>
<Sender>
 <SenderID>571099948</SenderID>
 <Sponsors>
  <Sponsor>
    <SponsorID>TEST01</SponsorID>
    <Contracts>
      <Contract>
        <ContractID>000001</ContractID>
        <Member>
          <SSN>1111111111</SSN>
          <Gender>M</Gender>
          <Benefits>
            <Benefit BenefitType="AAA">
            </Benefit>
            <Benefit BenefitType="BBB">
            </Benefit>
          </Benefits>
        </Member>
        <Member>
          <SSN>4444444444</SSN>
          <Gender>F</Gender>
          <Benefits>
            <Benefit BenefitType="AAA">
            </Benefit>
          </Benefits>
        </Member>
      </Contract>
      <Contract>
        <ContractID>0000002</ContractID>
        <Member>
          <SSN>2222222222</SSN>
          <Gender>F</Gender>
          <Benefits>
            <Benefit BenefitType="CCC">
            </Benefit>
            <Benefit BenefitType="DDD">
            </Benefit>
          </Benefits>
        </Member>
      </Contract>
      <Contract>
        <ContractID>0000003</ContractID>
        <Member>
          <SSN>333333333</SSN>
          <Gender>F</Gender>
          <Benefits> 
            <Benefit BenefitType="CCC">
            </Benefit>
          </Benefits>
        </Member>
      </Contract>
    </Contracts>
  </Sponsor>
  <Sponsor>
    <SponsorID>TEST02</SponsorID>
    <Contracts>
      <Contract>
        <ContractID>0000011</ContractID>
        <Member>
          <SSN>1111111111</SSN>
          <Gender>M</Gender>
          <Benefits>
          </Benefits>
        </Member>
      </Contract>
      <Contract>
        <ContractID>0000002</ContractID>
        <Member>
          <SSN>2222222222</SSN>
          <Gender>F</Gender>
          <Benefits>
          </Benefits>
        </Member>
      </Contract>
    </Contracts>
  </Sponsor>
</Sponsors>
</Sender>

我想从父节点获取合约节点的所有信息，以及 SponsorID.这是使用 XmlReader 部分读取 xml 文件的代码:

I want get all information of contract node, as well as SponsorID from the parent node. Here is the code to partially read xml file using XmlReader:

        static IEnumerable<XElement> SimpleStreamAxis(string inputUrl, string elementName)      
    {

            using (XmlReader reader = XmlReader.Create(inputUrl))
            {
                reader.MoveToContent();
                while (reader.Read())
                {
                    if (reader.NodeType == XmlNodeType.Element)
                    {
                        if (reader.Name == elementName)
                        {
                            XElement el = XNode.ReadFrom(reader) as XElement;
                            if (el != null)
                            {
                                yield return el;
                            }
                        }
                    }
                }
            }                  
    }

问题来了.我不能使用这个，因为整个赞助商树可能对内存来说太大了.

Here is the issue. I cannot use this, because the whole sponsor tree may be too large for the memory.

var sponsor = SimpleStreamAxis(file, "Sponsor");

我也不能使用这个，因为我不能只用合约节点信息告诉 SponsorID.

I cannot use this either, because I cannot tell SponsorID with only Contract node info.

var contract = SimpleStreamAxis(file, "Contract");

有没有办法读取Sponsor中的SponsorID，向前移动光标，读取这个Sponsor下的所有Contract节点，然后移动到下一个Sponsor读取SponsorID及其Contract节点等等?

Is there a way that I can read the SponsorID in Sponsor, move cursor forward, and read all the Contract nodes under this Sponsor, then move to next Sponsor and read SponsorID and its Contract nodes and so on?

推荐答案

试试这个:

using (XmlReader xmlReader = XmlReader.Create("file.xml"))
{
    while (xmlReader.Read())
    {
        if (xmlReader.ReadToFollowing("SponsorID"))
        {
            string sponsorId = xmlReader.ReadElementContentAsString();

            // process SponsorID
            Console.WriteLine(sponsorId);

            if (xmlReader.ReadToFollowing("Contract"))
            {
                do
                {
                    XmlReader contractSubtree = xmlReader.ReadSubtree();
                    XElement contractElement = XElement.Load(contractSubtree);

                    // process Contract
                    Console.WriteLine(contractElement.Element("ContractID"));

                } while (xmlReader.ReadToNextSibling("Contract"));
            }
        }
    }
}

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