如何在java中使用dom解析器按属性获取元素 [英] how to get element by attribute using dom parser in java

问题描述

我不知道如何通过属性获取元素.我尝试了以下内容，但由于 item(1) 可能会随着循环的进行而发生变化，因此出现错误.一些字段标签可能会被剥离.所以位置可能会改变.我想得到:

I am not getting an idea how to get an element by its attribute. I tried something as below but getting error as the item(1) might change as the loop goes on. some field tags may be stripped off. so position might change. I want to get:

<field name="Test/Content/Modified">Thu Jun 01 13:11:43 2014</field>

XML:

 <assets>
        <document path="some/path/1">
            <metadata>                    
                <field name="Test/Content/Date">2013-12-20</field>
                <field name="Test/Content/Modified">Thu Jun 01 13:11:43 2014</field>
                <field name="Test/Locale">en_US</field>
                <field name="Test/Content/SubSolution"></field>
            </metadata>
        </document>
        <document path="some/path/2">
            <metadata>                
                <field name="Test/Content/Date">2013-12-20</field>
                <field name="Test/Locale">en_US</field>
                <field name="Test/Content/Modified">Thu Jun 01 13:11:43 2014</field>
                <field name="Test/Content/SubSolution"></field>
            </metadata>
        </document>
 <assets>

java 部分代码:

DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse("E:\\example.xml");

List<String> list = new ArrayList<>();

NodeList nList = doc.getElementsByTagName("document");
for (int i = 0; i < nList.getLength(); i++) {
    Node nNode = nList.item(i);
    if (nNode.getNodeType() == Node.ELEMENT_NODE) {
        Element eElement = (Element) nNode;
        Date date = new Date(eElement.getElementsByTagName("field").item(1).getTextContent());
        System.out.println(date);
        Date date1 = new Date(2014 - 1900, 06 - 1, 04);
        if (date.compareTo(date1) == 1) {
            list.add(eElement.getAttribute("path").trim());
        }
    }
}

推荐答案

您需要遍历 field 节点并检查匹配的属性值:

You need to loop over the field nodes and check the matching attribute value:

    NodeList nList = doc.getElementsByTagName("document");
    for (int i = 0; i < nList.getLength(); i++) {
        Node nNode = nList.item(i);
        if (nNode.getNodeType() == Node.ELEMENT_NODE) {
            Element eElement = (Element) nNode;
            NodeList fieldNodes = eElement.getElementsByTagName("field");
            for(int j = 0; j < fieldNodes.getLength(); j++) {
                Node fieldNode = fieldNodes.item(j);
                NamedNodeMap attributes = fieldNode.getAttributes();
                Node attr = attributes.getNamedItem("name");
                if(attr != null) {
                    if(attr.getTextContent().equals("Test/Content/Modified")) {
                        Date date = new Date(fieldNode.getTextContent());
                        System.out.println(date);
                        Date date1 = new Date(2014 - 1900, 06 - 1, 04);
                        if (date.compareTo(date1) == 1) {
                            list.add(eElement.getAttribute("path").trim());
                        }
                    }
                }
            }
        }
    }

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