dom4j 通过 org.dom4j.XPath 设置命名空间来支持 带namespace 的 xpath

测试文件 test.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>cn.zno</groupId>
    <artifactId>z-test</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>xmlunit</groupId>
            <artifactId>xmlunit</artifactId>
            <version>1.6</version>
            <scope>test</scope>
        </dependency>

    </dependencies>
</project>

test.xml

所需依赖

    <dependencies>
        <dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.6.1</version>
        </dependency>
        <dependency>
            <groupId>jaxen</groupId>
            <artifactId>jaxen</artifactId>
            <version>1.1.6</version>
        </dependency>
    </dependencies>

测试代码

import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import javax.xml.transform.TransformerFactoryConfigurationError;

import org.dom4j.Document;
import org.dom4j.Node;
import org.dom4j.XPath;
import org.dom4j.io.SAXReader;
import org.dom4j.xpath.DefaultXPath;

public class Dom4jDemo {

    public static void main(String[] args) throws TransformerFactoryConfigurationError, Exception {
        InputStream is = Dom4jDemo.class.getResourceAsStream("/test.xml");

        SAXReader saxReader = new SAXReader();
        Map<String, String> namespaceURIs = new HashMap<String, String>();
        namespaceURIs.put("a", "http://maven.apache.org/POM/4.0.0");
        namespaceURIs.put("xsi", "http://www.w3.org/2001/XMLSchema-instance");
        Document doc = saxReader.read(is);

        XPath xpath = new DefaultXPath("//a:project/a:dependencies/a:dependency[a:groupId/text()='junit' and a:artifactId/text()='junit']/a:version");
        xpath.setNamespaceURIs(namespaceURIs);
        Node versionNode = xpath.selectSingleNode(doc);

        System.out.println(versionNode.getText());

    }
}

输出结果

4.12

注意：

1） XPath 是 org.dom4j.XPath

2） select 时的入参是上下文，比如 a node or a list of nodes

3）与 DocumentFactory 设置命名空间不同之处，XPath 可应用于多个document

4）org.dom4j.XPath 只有一个实现类 DefaultXPath