使用XPath解析相同的XML元素

Question

<time-layout time-coordinate="local" summarization="none">
      <layout-key>k-p24h-n7-1</layout-key>
      <start-valid-time>2013-10-30T08:00:00-07:00</start-valid-time>
      <end-valid-time>2013-10-30T20:00:00-07:00</end-valid-time>
      <start-valid-time>2013-10-31T08:00:00-07:00</start-valid-time>
      <end-valid-time>2013-10-31T20:00:00-07:00</end-valid-time>
      <start-valid-time>2013-11-01T08:00:00-07:00</start-valid-time>
      <end-valid-time>2013-11-01T20:00:00-07:00</end-valid-time>
      <start-valid-time>2013-11-02T08:00:00-07:00</start-valid-time>
      <end-valid-time>2013-11-02T20:00:00-07:00</end-valid-time>
      <start-valid-time>2013-11-03T07:00:00-08:00</start-valid-time>
      <end-valid-time>2013-11-03T19:00:00-08:00</end-valid-time>
      <start-valid-time>2013-11-04T07:00:00-08:00</start-valid-time>
      <end-valid-time>2013-11-04T19:00:00-08:00</end-valid-time>
      <start-valid-time>2013-11-05T07:00:00-08:00</start-valid-time>
      <end-valid-time>2013-11-05T19:00:00-08:00</end-valid-time>
    </time-layout>
    <time-layout time-coordinate="local" summarization="none">
      <layout-key>k-p24h-n6-2</layout-key>
      <start-valid-time>2013-10-30T20:00:00-07:00</start-valid-time>
      <end-valid-time>2013-10-31T09:00:00-07:00</end-valid-time>
      <start-valid-time>2013-10-31T20:00:00-07:00</start-valid-time>
      <end-valid-time>2013-11-01T09:00:00-07:00</end-valid-time>
      <start-valid-time>2013-11-01T20:00:00-07:00</start-valid-time>
      <end-valid-time>2013-11-02T09:00:00-07:00</end-valid-time>
      <start-valid-time>2013-11-02T19:00:00-07:00</start-valid-time>
      <end-valid-time>2013-11-03T08:00:00-08:00</end-valid-time>
      <start-valid-time>2013-11-03T19:00:00-08:00</start-valid-time>
      <end-valid-time>2013-11-04T08:00:00-08:00</end-valid-time>
      <start-valid-time>2013-11-04T19:00:00-08:00</start-valid-time>
      <end-valid-time>2013-11-05T08:00:00-08:00</end-valid-time>
    </time-layout>
    <time-layout time-coordinate="local" summarization="none">
      <layout-key>k-p3h-n35-3</layout-key>
      <start-valid-time>2013-10-30T11:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-30T14:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-30T17:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-30T20:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-30T23:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T02:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T05:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T08:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T11:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T14:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T17:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T20:00:00-07:00</start-valid-time>
      <start-valid-time>2013-10-31T23:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T02:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T05:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T08:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T11:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T14:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T17:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-01T23:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-02T05:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-02T11:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-02T17:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-02T23:00:00-07:00</start-valid-time>
      <start-valid-time>2013-11-03T04:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-03T10:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-03T16:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-03T22:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-04T04:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-04T10:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-04T16:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-04T22:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-05T04:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-05T10:00:00-08:00</start-valid-time>
      <start-valid-time>2013-11-05T16:00:00-08:00</start-valid-time>
    </time-layout>

Currently I am parsing XML using XPath in Java. All is good, until I see these three blocks. What stumps me is that I am met with three <time-layout time-coordinate="local" summarization="none"> each with different types of information inside. My current "hack" for this is renaming each local as local1 , local2 , and local3 , so I parse with XPath through /dwml/data/time-layout[@time-coordinate='local3']/start-valid-time/text() . That's sort of a hack, but since I will be soon reading the XML directly from the site where this XML is pulled, I'd like to not use that way, or perhaps, I cannot use that hack. Since there are three similarly named elements there, how do I parse only the third one with XPath, without renaming one of the attributes?

Thanks!

PS <layout-key> values are different everytime, so I cannot hardcode it into my parser.

Answer 1

Well you could check for the existence of <end-valid-time> in your xpath predicate and if it's not there, you're looking at the 3rd element.

//time-layout[not(./end-valid-time)]

That's also a bit of a hack, but at least it's all in the xpath.

Answer 2

使用谓词：

//time-layout[3]