dom4j中使用xpath解析带命名空间的xml文件,取不到节点的解决办法

XML文件如下:

<?xml version="1.0" encoding="gbk" standalone="yes"?>
<unit xmlns="http://www.sdml.info/srcML/src" xmlns:cpp="http://www.sdml.info/srcML/cpp">
	<cpp:ifndef>
		<name>test</name>
	</cpp:ifndef>
	<class>class</class>
</unit>

解析代码如下:

public static void main(String [] args){
			Document document = XmlTools.getDoc(file.getPath());
			HashMap xmlMap = new HashMap();
			xmlMap.put("src", "http://www.sdml.info/srcML/src");
			xmlMap.put("cpp", "http://www.sdml.info/srcML/cpp");
			// 以下可以访问到
			XPath x0 = document.createXPath("unit/src:class");
			XPath x1 = document.createXPath("src:unit/src:class");
			XPath x2 = document.createXPath("/unit/src:class");
			XPath x3 = document.createXPath("unit/src:class");
			XPath x4 = document.createXPath("/unit/cpp:define");
			XPath x6 = document.createXPath("unit/cpp:define");
			XPath x7 = document.createXPath("src:unit/cpp:define");
			// 以下访问不到
			XPath x8 = document.createXPath("unit/class");
			XPath x9 = document.createXPath("unit/define");
			XPath x10 = document.createXPath("/unit/class");
			XPath x11 = document.createXPath("/unit/define");
			XPath x12 = document.createXPath("src:unit/class");
			XPath x13 = document.createXPath("src:unit/define");
			XPath x14 = document.createXPath("unit/cpp:class");
			XPath x15 = document.createXPath("unit/src:define");
			test(x0, document, xmlMap);
			test(x1, document, xmlMap);
			test(x2, document, xmlMap);
			test(x3, document, xmlMap);
			test(x4, document, xmlMap);
			test(x6, document, xmlMap);
			test(x7, document, xmlMap);
			test(x8, document, xmlMap);
			test(x9, document, xmlMap);
			test(x10, document, xmlMap);
			test(x11, document, xmlMap);
			test(x12, document, xmlMap);
			test(x13, document, xmlMap);
			test(x14, document, xmlMap);
			test(x15, document, xmlMap);
}
	static void test(XPath x, Document doc, Map map) {
		x.setNamespaceURIs(map);
		System.out.println("运行结果:"+x.selectNodes(doc).size());
	}

运行结果如下:

运行结果:1
运行结果:1
运行结果:1
运行结果:1
运行结果:1
运行结果:1
运行结果:1
运行结果:0
运行结果:0
运行结果:0
运行结果:0
运行结果:0
运行结果:0
运行结果:0
运行结果:0