用于解析复杂XML文件的Java代码

Question

Below is a program written to parse the accompanying XML file.

Problem: There are two lane-IDs, but the output of my code keeps outputting only one. I expect the output to be:

Current Element: detector-report
Detector ID : I-74 NB from 12th Ave to 7th Ave
Status : operational

Lane-ID : 1
Lane - ID: 2

The current code still outputs 1 on the last line.

import org.w3c.dom.*;
import javax.xml.parsers.*;
import java.io.*;

public class FinalTrial {
    public static void main(String argv[]) {
        try {
            File fXmlFile = new File("workFile_09282014 22-10-34c.xml");
            DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
            Document doc = dBuilder.parse(fXmlFile);

            doc.getDocumentElement().normalize();
            System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
            NodeList nList = doc.getElementsByTagName("detector-report");
            System.out.println("----------------------------");

            for (int temp = 0; temp < nList.getLength(); temp++) {
                Node nNode = nList.item(temp);
                System.out.println("\nCurrent Element :" + nNode.getNodeName());

                if (nNode.getNodeType() == Node.ELEMENT_NODE) {
                    Element eElement = (Element) nNode;
                    System.out.println("Detector ID : " + eElement.getElementsByTagName("detector-id").item(0).getTextContent());
                    System.out.println("Status : " + eElement.getElementsByTagName("status").item(0).getTextContent());
                    NodeList lanes = eElement.getElementsByTagName("lane");
                    System.out.println(lanes.getLength());
                    for (int j = 0; j<lanes.getLength(); j++) {
                         Element lane = (Element) lanes.item(0);
                         System.out.println("Lane-ID : " + lane.getElementsByTagName("lane-id").item(0).getTextContent());
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Below is the accompanying XML file:

<?xml version="1.0" encoding="utf-8"?>
<trafficDetectorData xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xmlns="http://www.dummy-temp-address" xmlns:lrms="http://www.dummy-lrms-address" xsi:schemaLocation="http://www.dummy-temp-address C:\temp\test\Detectors.xsd">
    <detector-report>
      <detector-id>I-74 NB from Ave of the Cities t</detector-id>
      <status>operational</status>
        <lane>
          <lane-id>1</lane-id>
          <count>1</count>
          <volume>1</volume>
          <occupancy>0</occupancy>
          <speed>122</speed>
          <classes>
            <class>
              <class-id>Small</class-id>
              <count>1</count>
              <volume>1</volume>
            </class>
            <class>
              <class-id>Medium</class-id>
            </class>
            <class>
              <class-id>Large</class-id>
            </class>
          </classes>
        </lane>
        <lane>
          <lane-id>2</lane-id>
          <occupancy>0</occupancy>
          <speed>137</speed>
          <classes>
            <class>
              <class-id>Small</class-id>
            </class>
            <class>
              <class-id>Medium</class-id>
            </class>
            <class>
              <class-id>Large</class-id>
            </class>
          </classes>
        </lane>
    </detector-report>
    <detector-report>
      <detector-id>I-74 NB from 12th Ave to 7th Ave</detector-id>
      <status>operational</status>
        <lane>
          <lane-id>1</lane-id>
          <count>3</count>
          <volume>3</volume>
          <occupancy>3</occupancy>
          <speed>100</speed>
          <classes>
            <class>
              <class-id>Small</class-id>
              <count>3</count>
              <volume>3</volume>
            </class>
            <class>
              <class-id>Medium</class-id>
            </class>
            <class>
              <class-id>Large</class-id>
            </class>
          </classes>
        </lane>
        <lane>
          <lane-id>2</lane-id>
          <count>4</count>
          <volume>4</volume>
          <occupancy>3</occupancy>
          <speed>116</speed>
          <classes>
            <class>
              <class-id>Small</class-id>
              <count>4</count>
              <volume>4</volume>
            </class>
            <class>
              <class-id>Medium</class-id>
            </class>
            <class>
              <class-id>Large</class-id>
            </class>
          </classes>
        </lane>
    </detector-report>
</trafficDetectorData>

Answer 1

I urge most developers to use established libraries for XML document handling, to avoid errors such as not properly escaping attribute values.

Java's built-in XML parsing library works very well (org.w3c.dom.Document, etc...).