dom4j 通过 org.dom4j.DocumentFactory 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>

测试类

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

import javax.xml.transform.TransformerFactoryConfigurationError;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentFactory;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

public class Dom4jDemo {

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

SAXReader saxReader = new SAXReader();
DocumentFactory documentFactory = saxReader.getDocumentFactory();
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");
documentFactory.setXPathNamespaceURIs(namespaceURIs);
Document doc = saxReader.read(is);

Node versionNode = doc.selectSingleNode("//a:project/a:dependencies/a:dependency[a:groupId/text()='junit' and a:artifactId/text()='junit']/a:version");
System.out.println(versionNode.getText());

}
}

测试结果

4.12

注意：

1） 依赖 jaxen 而非 xalan （这个是转换时用的）

2）a:project 即是 qualified name ，全称：

http://maven.apache.org/POM/4.0.0/:project

3） xpath 语法：

https://www.w3.org/TR/xpath/