我正在尝试删除XML文件中的特定节点。 我能够获取我必须删除的属性ID，但后来无法删除该节点。它给出了例外。
这是我的代码：
public class RemoveXmlElement {
public static final String xmlFilePath = "C:\\Xfile.xml";
int s = 0;
String username = "";
String fullname = "";
String message = "";
List getFiledata = null;
public List readXML(int x) {
System.out.println("x :" + x);
try {
File xmlFile = new File(xmlFilePath);
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document doc = documentBuilder.parse(xmlFile);
doc.getDocumentElement().normalize();
Node node = doc.getElementsByTagName("main").item(x);
System.out.println("node :" + node);
NodeList nodeList = node.getChildNodes();
System.out.println("In Remove==================================" + nodeList.getLength());
if (nodeList.getLength() > 0) {
getFiledata = new ArrayList();
Element element = (Element) doc.getElementsByTagName("SNo").item(x);
NodeList y = doc.getElementsByTagName("SNo");
element.getAttributeNode("" + x);
System.out.println("doc.getElementsByTagName('SrNo').item(x); " + element);
doc.removeChild(element);
for (int c = 0; c < y.getLength(); c++) {
// Node node1 = nodeList.item(c);
// node.getParentNode().removeChild(node1);
//doc.removeChild(y[c].);
}
//element.getParentNode().removeChild(element);
}
} catch (Exception e) {
e.printStackTrace();
}
return getFiledata;
}
}
我想只删除与servlet中作为参数接收的数字对应的S_no节点。当我使用NodeList nodeList = node.getChildNodes();时
我得到空指针异常，否则没有任何反应。代码运行但不删除节点。
我也尝试使用for循环来获取属性值但没有成功。
我想我需要获得属性ID。或者是因为Attribute Id是String而我试图找到使用整数？
这是我得到的例外：
java.lang.NullPointerException
at com.idbi.dp.Model.RemoveXmlElement.readXML(RemoveXmlElement.java:43)
at com.idbi.dp.Controller.remove_servlet.doPost(remove_servlet.java:32)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
java.lang.NullPointerException
at com.idbi.dp.Model.RemoveXmlElement.readXML(RemoveXmlElement.java:43)
at com.idbi.dp.Controller.remove_servlet.doPost(remove_servlet.java:32)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)
我被困在这里.. 请指出我的错误，如果可能的话，提供一个解决我的问题的提示。
忘记包含XML文件：
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
- <main>
- <SrNo id="1">
<username>XRG</username>
<fullname>Xavier</fullname>
<message>sfdgsdgdf<@@@/message>
</SrNo>
- <SrNo id="2">
<username>ROB</username>
<fullname>Robert</fullname>
<message>adsadda$$$</message>
</SrNo>
</main>