我有一个像这样的xml的应用程序：
<root>
<info>
.....
</info>
<type>
<object_type>..</object_type>
<prop>
<data>
.... . ..
</prop>
<param>
....
</param>
<param>
....
</param>
<param>
....
</param>
等
所有这些数据都是从XML解析的，现在用户应该可以编辑数据了。
所以我已经实现了一种更新params的方法：
但由于错误编写了Xpath语句，它给了我一个例外：
javax.xml.xpath.XPathExpressionException
at com.sun.org.apache.xpath.internal.jaxp.XPathImpl.compile(Unknown Source)
at xmleditor.service.XMLEditorService.updateParameters(XMLEditorService.java:96)
at xmleditor.gui.XmlEditorMain$5$1.tableChanged(XmlEditorMain.java:364)
at javax.swing.table.AbstractTableModel.fireTableChanged(Unknown Source)
at javax.swing.table.AbstractTableModel.fireTableCellUpdated(Unknown Source)
at javax.swing.table.DefaultTableModel.setValueAt(Unknown Source)
at javax.swing.JTable.setValueAt(Unknown Source)
at javax.swing.JTable.editingStopped(Unknown Source)
at javax.swing.AbstractCellEditor.fireEditingStopped(Unknown Source)
at javax.swing.DefaultCellEditor$EditorDelegate.stopCellEditing(Unknown Source)
at javax.swing.DefaultCellEditor.stopCellEditing(Unknown Source)
at javax.swing.JTable$GenericEditor.stopCellEditing(Unknown Source)
at javax.swing.DefaultCellEditor$EditorDelegate.actionPerformed(Unknown Source)
at javax.swing.JTextField.fireActionPerformed(Unknown Source)
at javax.swing.JTextField.postActionEvent(Unknown Source)
at javax.swing.JTextField$NotifyAction.actionPerformed(Unknown Source)
at javax.swing.SwingUtilities.notifyAction(Unknown Source)
at javax.swing.JComponent.processKeyBinding(Unknown Source)
at javax.swing.JComponent.processKeyBindings(Unknown Source)
at javax.swing.JComponent.processKeyEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: javax.xml.transform.TransformerException: Ett platssteg förväntades efter token '/' eller '//'.
at com.sun.org.apache.xpath.internal.compiler.XPathParser.error(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.RelativeLocationPath(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.LocationPath(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.PathExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.UnionExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.UnaryExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.MultiplicativeExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.AdditiveExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.RelationalExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.EqualityExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.AndExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.OrExpr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.Expr(Unknown Source)
at com.sun.org.apache.xpath.internal.compiler.XPathParser.initXPath(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
at com.sun.org.apache.xpath.internal.XPath.<init>(Unknown Source)
... 41 more
所以我尝试做的是从用户编辑的表中获取rowCount并将其存储在int x中。然后我将columnName存储在String columnName中。我试图在我的xpath表达式中使用这些变量来根据用户选择的ObjectType找到完美的位置。并更新并将其保存在xml文件中。但不知何故，似乎我的xpath表达式是错误的，或者变换器无法以某种方式读取它。因为我也得到了这个：
Caused by: javax.xml.transform.TransformerException
这是我的java代码：
// Update the parameters
public void updateParameters(String columnName, Object data, int x,
Type type) throws ParserConfigurationException, SAXException,
IOException, XPathExpressionException {
File file = new File("xmlFiles/CoreDatamodel.xml");
System.out.println("Incoming String value : " + data);
System.out.println("Index value : " + x);
DocumentBuilderFactory builderFactory = DocumentBuilderFactory
.newInstance();
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document xmlDocument = builder.parse(file);
XPath xPath = XPathFactory.newInstance().newXPath();
Node node = (Node) xPath.compile(
"//OBJECT_TYPE[text() = '" + type.getObjectType()
+ "']/following-sibling::param/[position()='" + x
+ "']/'" + columnName + "'").evaluate(xmlDocument,
XPathConstants.NODESET);
// Set new NodeValue
node.setNodeValue(data.toString());
// Save the new updates
try {
save(file, xmlDocument);
} catch (Exception e) {
e.printStackTrace();
}
}
// Method for saving the new updated data.
public void save(File file, Document doc) throws Exception {
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
StringWriter writer = new StringWriter();
StreamResult result = new StreamResult(writer);
// Holds the old document
DOMSource source = new DOMSource(doc);
transformer.transform(source, result);
String s = writer.toString();
System.out.println(s);
FileWriter fileWriter = new FileWriter(file);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
bufferedWriter.write(s);
bufferedWriter.flush();
bufferedWriter.close();
}
如何解决这个问题？
更新：
此代码解决了问题，但节点为null，因此表达式正在运行。
Node node = (Node) xPath.compile(
"//OBJECT_TYPE[text() = '" + type.getObjectType()
+ "']/following-sibling::param[position()= '" + x
+ "']/" + columnName + "").evaluate(xmlDocument,
XPathConstants.NODE);
答案 0 :(得分：1)