如何使用Java检索XML的元素值？ [英] How to retrieve element value of XML using Java?

问题描述

我是XML新手。我想根据请求名称阅读以下XML。请帮我看看如何在Java中阅读以下XML -

I am new to XML. I want to read the following XML on the basis of request name. Please help me on how to read the below XML in Java -

<?xml version="1.0"?>
    <config>
        <Request name="ValidateEmailRequest">
            <requestqueue>emailrequest</requestqueue>
            <responsequeue>emailresponse</responsequeue>
        </Request>
        <Request name="CleanEmail">
            <requestqueue>Cleanrequest</requestqueue>
            <responsequeue>Cleanresponse</responsequeue>
        </Request>
    </config>

推荐答案

如果您的XML是String，那么你可以做以下内容：

If your XML is a String, Then you can do the following:

String xml = ""; //Populated XML String....

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(new InputSource(new StringReader(xml)));
Element rootElement = document.getDocumentElement();

如果你的XML在一个文件中，那么文档文件将实例化如下：

If your XML is in a file, then Document document will be instantiated like this:

Document document = builder.parse(new File("file.xml"));

document.getDocumentElement（）返回给你作为文档文档元素的节点（在您的情况下为< config> ）。

The document.getDocumentElement() returns you the node that is the document element of the document (in your case <config>).

一旦你有 rootElement ，你可以访问元素的属性（通过调用 rootElement.getAttribute（）方法）等等。关于java的 org.w3c.dom.Element的更多方法

Once you have a rootElement, you can access the element's attribute (by calling rootElement.getAttribute() method), etc. For more methods on java's org.w3c.dom.Element

有关java的更多信息 DocumentBuilder & DocumentBuilderFactory 。 请记住，提供的示例创建了一个XML DOM树，因此如果您有一个巨大的XML数据，那么树可能会很大。

More info on java DocumentBuilder & DocumentBuilderFactory. Bear in mind, the example provided creates a XML DOM tree so if you have a huge XML data, the tree can be huge.

• 相关问题。

• Related question.

更新以下是获取元素$的元素< requestqueue>

Update Here's an example to get "value" of element <requestqueue>

protected String getString(String tagName, Element element) {
        NodeList list = element.getElementsByTagName(tagName);
        if (list != null && list.getLength() > 0) {
            NodeList subList = list.item(0).getChildNodes();

            if (subList != null && subList.getLength() > 0) {
                return subList.item(0).getNodeValue();
            }
        }

        return null;
    }

您可以有效地将其称为，

You can effectively call it as,

String requestQueueName = getString("requestqueue", element);

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