Question

我是java的新手，我想解析一个xml文件

我有一个像这样的

格式的xml文件

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <metadonnees>
        <factory type="factory1">
            <icones>
                <icone type="empty" path="src/ressources/UMP0%.png"/>
                <icone type="half" path="src/ressources/UMP33%.png"/>
                <icone type="full" path="src/ressources/UMP100%.png"/>
            </icones>
            <out type = "materiel1"/>
            <interval>100</interval>
        </factory>
        <factory type="factory2">
            <icones>
                <icone type="empty" path="src/ressources/UT0%.png"/>
                <icone type="half" path="src/ressources/UT33%.png"/>
                <icone type="full" path="src/ressources/UT100%.png"/>
            </icones>
            <enter type="materiel1" quantite="2"/>
            <out type="materiel2"/>
            <interval> 2 </interval>
        </factory>

    </metadonnees>

    <simulation>
        <factory type="factoty1" id="11" x="32" y="32"/>
        <factory type="factory2" id="21" x="320" y="32"/>

        <paths>
            <path de="11" vers="21" />
            <path de="21" vers="41" />
            <path de="41" vers="51" />
            </paths>
    </simulation>

</configuration>

我尝试用java阅读它，但我遇到了麻烦

NodeList config = document.getElementsByTagName("metadonnees");

for(int j = 0;j<config.getLength();j++) {

    NodeList usineList = document.getElementsByTagName("factory");
    for (int i = 0; i < usineList.getLength(); i++) {
        Node usine = usineList.item(i);
        if (usine.getNodeType() == Node.ELEMENT_NODE) {
            Element type = (Element) usine;
            String typeUsine = type.getAttribute("type");

            System.out.println(typeUsine);
        }
    }
}

这个列表我只是工厂类型

FACTORY1
FACTORY2
FACTORY1
FACTORY2

我想仅列出metadonnee部分中的数据所以我可以获得出厂设置以及如何单独获取图标

我该如何解决这个问题？

Answer 1

在您的代码中，document.getElementsByTagName("factory");会返回标记为<factory>的所有元素。如果要限制元数据metadonnees部分中的选择，可以使用XPath（XML路径语言）。

获取元素

获取元数据中的所有factory元素：

//metadonnees/factory

Java代码：

XPath xPath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xPath.compile("//metadonnees/factory");
NodeList usineList = (NodeList) expr.evaluate(document, XPathConstants.NODESET);
for (int i = 0; i < usineList.getLength(); i++) {
  Element usine = (Element) usineList.item(i);
  String typeUsine = usine.getAttribute("type");
  System.out.println(typeUsine);
}

获取属性

获取元数据中type元素的所有factory属性：

//metadonnees/factory/@type

Java代码：

XPath xPath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xPath.compile("//metadonnees/factory/@type");
NodeList typeList = (NodeList) expr.evaluate(document, XPathConstants.NODESET);
for (int i = 0; i < typeList.getLength(); i++) {
  Attr type = (Attr) typeList.item(i);
  System.out.println(type.getValue());
}

获取子节点

查询工厂的子节点时，需要以下xpath，这意味着查询从当前节点（.）开始，一直持续到元素<icone>为止：

.//icone

Java代码：

XPath xPath = XPathFactory.newInstance().newXPath();
NodeList usineList =
    (NodeList) xPath.evaluate("//metadonnees/factory", document, XPathConstants.NODESET);
for (int i = 0; i < usineList.getLength(); i++) {
  Element usine = (Element) usineList.item(i);
  NodeList icons = (NodeList) xPath.evaluate(".//icone", usine, XPathConstants.NODESET);
  System.out.println(usine.getAttribute("type"));

  for (int j = 0; j < icons.getLength(); j++) {
    Element icon = (Element) icons.item(j);
    String type = icon.getAttribute("type");
    String path = icon.getAttribute("path");
    String msg = "type=" + type + ", path=" + path;
    System.out.println(msg);
  }
}

结果：

factory1
type=empty, path=src/ressources/UMP0%.png
type=half, path=src/ressources/UMP33%.png
type=full, path=src/ressources/UMP100%.png
factory2
type=empty, path=src/ressources/UT0%.png
type=half, path=src/ressources/UT33%.png
type=full, path=src/ressources/UT100%.png

Answer 2

SimpleXml可以做到这一点：

final String data = ...
final SimpleXml simple = new SimpleXml();
final Element element = simple.fromXml(data);
for (final Element factory : element.children.get(0).children) {
    for (final Element icone : factory.children.get(0).children) {
        System.out.println(String.format("Factory: %s, Icone: %s", factory.attributes.get("type"), icone.attributes.get("type")));
    }
}

将输出：

Factory: factory1, Icone: empty
Factory: factory1, Icone: half
Factory: factory1, Icone: full
Factory: factory2, Icone: empty
Factory: factory2, Icone: half
Factory: factory2, Icone: full

从Maven Central：

<dependency>
    <groupId>com.github.codemonstur</groupId>
    <artifactId>simplexml</artifactId>
    <version>1.4.0</version>
</dependency>

用java读取XML文件

2 个答案:

获取元素

获取属性

获取子节点