用Java解析这个XML的最简单的方法？ [英] Simplest way to parse this XML in Java?

问题描述

我有以下XML：

     <ConfigGroup Name="Replication">
        <ValueInteger Name="ResponseTimeout">10</ValueInteger>
        <ValueInteger Name="PingTimeout">2</ValueInteger>
        <ValueInteger Name="ConnectionTimeout">10</ValueInteger>
        <ConfigGroup Name="Pool">
            <ConfigGroup Name="1">
                <ValueString Encrypted="false" Name="Host">10.20.30.40</ValueString>
                <ValueInteger Name="CacheReplicationPort">8899</ValueInteger>
                <ValueInteger Name="RadiusPort">12050</ValueInteger>
                <ValueInteger Name="OtherPort">4868</ValueInteger>
            </ConfigGroup>
            <ConfigGroup Name="2">
                <ValueString Encrypted="false" Name="Host">10.20.30.50</ValueString>
                <ValueInteger Name="CacheReplicationPort">8899</ValueInteger>
                <ValueInteger Name="RadiusPort">12050</ValueInteger>
                <ValueInteger Name="OtherPort">4868</ValueInteger>
            </ConfigGroup>
        </ConfigGroup>
     </ConfigGroup>

我只是想知道在Java中解析这个XML的最简单的方法是什么 - 我想要从两个主要成分（例如10.20.30.40和10.20.30.50）。注意，可能有两个以上的池条目（或根本没有）。

I just wondering what is the simplest way to parse this XML in Java - I want the value from the two host elements (e.g. 10.20.30.40 and 10.20.30.50). Note there may be more than two pool entries (or none at all).

我无法找到一个简单的例子，说明如何使用各种XML解析器进行Java

I'm having trouble finding a simple example of how to use the various XML parsers for Java.

非常感谢任何帮助。

谢谢！

推荐答案

搜索您要查找的最简单的方法是XPath。

The simplest way to search for what you are looking for, would be XPath.

try {

    //Load the XML File
    DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
    domFactory.setNamespaceAware(true);
    DocumentBuilder builder = domFactory.newDocumentBuilder();
    Document configuration = builder.parse("configs.xml");

    //Create an XPath expression
    XPathFactory xpathFactory = XPathFactory.newInstance();
    XPath xpath = xpathFactory.newXPath();
    XPathExpression expr = xpath.compile("//ConfigGroup/ValueString[@Name='Host']/text()");

    //Execute the XPath query
    Object result = expr.evaluate(configuration, XPathConstants.NODESET);
    NodeList nodes = (NodeList) result;

    //Parse the results
    for (int i = 0; i < nodes.getLength(); i++) {
        System.out.println(nodes.item(i).getNodeValue()); 
    }
} catch (ParserConfigurationException e) {
    System.out.println("Bad parser configuration");
    e.printStackTrace();
} catch (SAXException e) {
    System.out.println("SAX error loading the file.");
    e.printStackTrace();
} catch (XPathExpressionException e) {
    System.out.println("Bad XPath Expression");
    e.printStackTrace();
} catch (IOException e) {
    System.out.println("IO Error reading the file.");
    e.printStackTrace();
}

XPath表达式

"//ConfigGroup/ValueString[@Name='Host']/text()"

在XML中的任何位置查找ConfigGroup元素，然后在ConfigGroup元素中找到具有值Host的Name属性的ValueString元素。 @ Name =主机就像一个名为ValueString的元素的过滤器。和最后的text（），返回所选元素的文本节点。

looks for ConfigGroup elements anywhere in your XML, then finds ValueString elements within the ConfigGroup elements, that have a Name attribute with the value "Host". @Name=Host is like a filter for elements with the name ValueString. And text() at the end, returns the text node of the selected elements.

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