java - 如何使用 DOM XML 解析器解析 XML 文档

Question

我有一个 xml 文档，如下所示:

<travellingSalesmanProblemInstance>
    <name>blabla</name>
    <source>TSPLIBRARY</source>
    <description>52 locations in Nowhere</description>
    <doublePrecision>15</doublePrecision>
    <ignoredDigits>5</ignoredDigits>

    <graph>
        <vertex>
            <edge cost="6.661080993352356e+02">1</edge>
            <edge cost="2.811138559374119e+02">2</edge>
            <edge cost="3.956008088970497e+02">3</edge>
            <edge cost="2.912043955712207e+02">4</edge>
        </vertex>
        <vertex>
            <edge cost="2.561080993352356e+02">0</edge>
            <edge cost="2.711138559374119e+02">2</edge>
            <edge cost="6.556008088970497e+02">3</edge>
            <edge cost="7.9112043955712207e+02">4</edge>
        </vertex>
        ...
    </graph>
</travellingSalesmanProblemInstance>

我尝试读取此 xml 文件。但我失败了。

我用这个浏览所有 < vertex > 标签:

NodeList nList = doc.getElementsByTagName("vertex");
for (int i = 0; i < nList.getLength(); i++) 
{

但是如何获取这些 标签内的所有 元素呢？

谢谢!!

Answer 1

只需使用结果列表中的每个节点进行另一次选择

NodeList nList = doc.getElementsByTagName("vertex");
NodeList edgeList;

// For each vertex, get all "edge" children
for (int i = 0; i < nList.getLength(); i++)  {
    edgeList = ((Element)nList.item(i)).getElementsByTagName("edge");

    // For each edge under this vertex, do something
    for (int j = 0; j < edgeList.getLength(); j++) {

        // test that it works
        System.out.println(edgeList.item(j).getTextContent());
    }
}