6
在以下任何XPath的示例代碼的形式爲當源XML有一個命名空間前綴「// 的ElementName」返回NULL（見testWithNS()在底部的代碼）。爲什麼只有特定的XPath表達式查找節點時，XML有一個命名空間前綴
如果源xml沒有名稱空間前綴，則列出的所有XPath表達式將返回一個節點（請參見testNoNS()）。
我知道我可以通過設置NamespaceContext（如testWithNSContext()）解析XML，解析xml作爲名稱空間感知文檔，並在XPath中使用名稱空間前綴。但是我不想這樣做，因爲我的實際代碼需要處理帶或不帶名稱空間前綴的xml。
我的問題是，爲什麼只有是：
- //測試
- // child1
- // grandchild1
- //的child2
返回空值，但testWithNS()中的所有其他示例都返回節點？
輸出
testNoNS()
test = found
/test = found
//test = found
//test/* = found
//test/child1 = found
//test/child1/grandchild1 = found
//test/child2 = found
//child1 = found
//grandchild1 = found
//child1/grandchild1 = found
//child2 = found
testWithNS()
test = found
/test = found
//test = *** NOT FOUND ***
//test/* = found
//test/child1 = found
//test/child1/grandchild1 = found
//test/child2 = found
//child1 = *** NOT FOUND ***
//grandchild1 = *** NOT FOUND ***
//child1/grandchild1 = found
//child2 = *** NOT FOUND ***
testWithNSContext()
ns1:test = found
/ns1:test = found
//ns1:test = found
//ns1:test/* = found
//ns1:test/ns1:child1 = found
//ns1:test/ns1:child1/ns1:grandchild1 = found
//ns1:test/ns1:child2 = found
//ns1:child1 = found
//ns1:grandchild1 = found
//ns1:child1/ns1:grandchild1 = found
//ns1:child2 = found
代碼
import java.io.StringReader;
import java.util.Iterator;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;
import org.junit.Test;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
public class XPathBugTest {
private String xmlDec = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
private String xml = xmlDec +
"<test>" +
" <child1>" +
" <grandchild1/>" +
" </child1>" +
" <child2/>" +
"</test>";
private String xmlNs = xmlDec +
"<ns1:test xmlns:ns1=\"http://www.wfmc.org/2002/XPDL1.0\">" +
" <ns1:child1>" +
" <ns1:grandchild1/>" +
" </ns1:child1>" +
" <ns1:child2/>" +
"</ns1:test>";
final XPathFactory xpathFactory = XPathFactory.newInstance();
final XPath xpath = xpathFactory.newXPath();
@Test
public void testNoNS() throws Exception {
System.out.println("\ntestNoNS()");
final Document doc = getDocument(xml);
isFound("test", xpath.evaluate("test", doc, XPathConstants.NODE));
isFound("/test", xpath.evaluate("/test", doc, XPathConstants.NODE));
isFound("//test", xpath.evaluate("//test", doc, XPathConstants.NODE));
isFound("//test/*", xpath.evaluate("//test/*", doc, XPathConstants.NODE));
isFound("//test/child1", xpath.evaluate("//test/child1", doc, XPathConstants.NODE));
isFound("//test/child1/grandchild1", xpath.evaluate("//test/child1/grandchild1", doc, XPathConstants.NODE));
isFound("//test/child2", xpath.evaluate("//test/child2", doc, XPathConstants.NODE));
isFound("//child1", xpath.evaluate("//child1", doc, XPathConstants.NODE));
isFound("//grandchild1", xpath.evaluate("//grandchild1", doc, XPathConstants.NODE));
isFound("//child1/grandchild1", xpath.evaluate("//child1/grandchild1", doc, XPathConstants.NODE));
isFound("//child2", xpath.evaluate("//child2", doc, XPathConstants.NODE));
}
@Test
public void testWithNS() throws Exception {
System.out.println("\ntestWithNS()");
final Document doc = getDocument(xmlNs);
isFound("test", xpath.evaluate("test", doc, XPathConstants.NODE));
isFound("/test", xpath.evaluate("/test", doc, XPathConstants.NODE));
isFound("//test", xpath.evaluate("//test", doc, XPathConstants.NODE));
isFound("//test/*", xpath.evaluate("//test/*", doc, XPathConstants.NODE));
isFound("//test/child1", xpath.evaluate("//test/child1", doc, XPathConstants.NODE));
isFound("//test/child1/grandchild1", xpath.evaluate("//test/child1/grandchild1", doc, XPathConstants.NODE));
isFound("//test/child2", xpath.evaluate("//test/child2", doc, XPathConstants.NODE));
isFound("//child1", xpath.evaluate("//child1", doc, XPathConstants.NODE));
isFound("//grandchild1", xpath.evaluate("//grandchild1", doc, XPathConstants.NODE));
isFound("//child1/grandchild1", xpath.evaluate("//child1/grandchild1", doc, XPathConstants.NODE));
isFound("//child2", xpath.evaluate("//child2", doc, XPathConstants.NODE));
}
@Test
public void testWithNSContext() throws Exception {
System.out.println("\ntestWithNSContext()");
final Document doc = getDocumentNS(xmlNs);
xpath.setNamespaceContext(new MyNamespaceContext());
isFound("ns1:test", xpath.evaluate("ns1:test", doc, XPathConstants.NODE));
isFound("/ns1:test", xpath.evaluate("/ns1:test", doc, XPathConstants.NODE));
isFound("//ns1:test", xpath.evaluate("//ns1:test", doc, XPathConstants.NODE));
isFound("//ns1:test/*", xpath.evaluate("//ns1:test/*", doc, XPathConstants.NODE));
isFound("//ns1:test/ns1:child1", xpath.evaluate("//ns1:test/ns1:child1", doc, XPathConstants.NODE));
isFound("//ns1:test/ns1:child1/ns1:grandchild1", xpath.evaluate("//ns1:test/ns1:child1/ns1:grandchild1", doc, XPathConstants.NODE));
isFound("//ns1:test/ns1:child2", xpath.evaluate("//ns1:test/ns1:child2", doc, XPathConstants.NODE));
isFound("//ns1:child1", xpath.evaluate("//ns1:child1", doc, XPathConstants.NODE));
isFound("//ns1:grandchild1", xpath.evaluate("//ns1:grandchild1", doc, XPathConstants.NODE));
isFound("//ns1:child1/ns1:grandchild1", xpath.evaluate("//ns1:child1/ns1:grandchild1", doc, XPathConstants.NODE));
isFound("//ns1:child2", xpath.evaluate("//ns1:child2", doc, XPathConstants.NODE));
}
private void isFound(String xpath, Object object) {
System.out.println(xpath + " = " + (object == null ? "*** NOT FOUND ***" : "found"));
}
private Document getDocument(final String xml) throws Exception {
final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
return factory.newDocumentBuilder().parse(new InputSource(new StringReader(xml)));
}
private Document getDocumentNS(final String xml) throws Exception {
final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
return factory.newDocumentBuilder().parse(new InputSource(new StringReader(xml)));
}
public class MyNamespaceContext implements NamespaceContext {
@Override
public String getNamespaceURI(String prefix) {
if ("ns1".equals(prefix)) {
return "http://www.wfmc.org/2002/XPDL1.0";
}
return XMLConstants.NULL_NS_URI;
}
@Override
public String getPrefix(String uri) {
throw new UnsupportedOperationException();
}
@Override
public Iterator getPrefixes(String uri) {
throw new UnsupportedOperationException();
}
}
}
更新以下撒克遜測試
我已經使用撒克遜改變XPahtFactory線到此
現在測試的相同碼final XPathFactory xpathFactory = new net.sf.saxon.xpath.XPathFactoryImpl();
使用撒克遜人在testWithNS()回報*** NOT FOUND ***所有行，而不是像「// 的ElementName」只是那些與默認Xalan的實現。
鑑於我正在使用非名稱空間感知文檔生成器工廠來解析xml，爲什麼這些xpaths都沒有工作，只有一些Xalan？
看起來像XPath實現中的錯誤。 – obecker
我曾想過，但認爲它也可能是某人顯而易見的事情。我會用撒克遜人嘗試以上方法並報告發生了什麼。 –