java - 如何在java中使用xpath获取xml的一部分

Question

基于 xpath，我想选择 xml 的一部分，并选择我想用作另一个 xml 源的部分。

例如:

 <root>
    <a type="t1">
        <property name="data" value="val1"/>
    </a>
    <a type="t2">
        <property name="data" value="val2"/>
    </a>
   <a type="t1">
        <property name="data" value="val2"/>
    </a>
 </root>

xpath:/root/a[@type="t1"]/

所选的 xml 为

<root>
    <a type="t1">
        <property name="data" value="val1"/>
    </a>
    <a type="t1">
        <property name="data" value="val2"/>
    </a>
 </root>

同样我想在java中用作另一个xml源。请帮帮我。

Answer 1

加载 XML 并找到您要查找的节点...

DocumentBuilderFactory f = DocumentBuilderFactory.newInstance();
DocumentBuilder b = f.newDocumentBuilder();
Document d = b.parse(...);

// Find all nodes with the attribute of type equal to `t1`
// You could use //*/a[@type='t1'] if you wanted to narrow it down
// This find ALL matches through out the document...
String expression = "//*[@type='t1']";
XPath xPath = XPathFactory.newInstance().newXPath();
Object result = xPath.compile(expression).evaluate(d, XPathConstants.NODESET);

NodeList nodes = (NodeList) result;

创建一个新的文档....

Document d2 = b.newDocument();
Element root = d2.createElement("root");
d2.appendChild(root);

将节点从第一个添加到第二个...

for (int i = 0; i < nodes.getLength(); i++) {
    Node node = nodes.item(i);
    d2.adoptNode(node);
    root.appendChild(node);
}

这应该导致......

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<root>
    <a type="t1">
        <property name="data" value="val1"/>
    </a>
    <a type="t1">
        <property name="data" value="val2"/>
    </a>
</root>