计算特定节点下的xml节点

Question

<element>
  <slot name="slot1">
    <port status="active"/>
    <port status="inactive"/>
  </slot>
  <slot name="slot2">
    <port status="active"/>
  </slot>
</element>

NodeList listOfElement = doc.getElementsByTagName("port");这给出了xml文件中的端口总数。

我需要找出slot1下有多少个端口。

Answer 1

一种方法是使用xpath过滤掉结果列表：

XPath xpath = XPathFactory.newInstance().newXPath();            
NodeList list=(NodeList) xpath.evaluate("/element/slot[@name='slot1']/port",doc, XPathConstants.NODESET);

这将只计算名为'slot1'的插槽下的端口。

Answer 2

您可以在Java SE中使用javax.xml.xpath库，并利用count函数：

import java.io.FileInputStream;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;

import org.xml.sax.InputSource;

public class Demo {

    public static void main(String[] args) throws Exception {
        XPath xp = XPathFactory.newInstance().newXPath();
        InputSource xml = new InputSource(new FileInputStream("input.xml"));
        double count = (Double) xp.evaluate("count(//slot[@name='slot1']/port)", xml, XPathConstants.NUMBER);
    }

}

Answer 3

这是怎么回事？

var slot1 = doc.getElementsByName("slot1");
var slot1_count = slot1[0].getElementsByTagName("port").length;