我目前正在开发一个xml项目.到目前为止,我已经使用Dom Parser成功将我的xml链接到我的
java类.我在下面提供了代码.我正在努力的是将我的startdate的月份更新为1,因此像这样的2/2 / 2013,3 / 1/2013 …将相应地在xml文件中更改.我在底部调用updateDate方法,但是当我调用它时,xml文件不会更新它的值.帮助将不胜感激
data.xml之前
<?xml version="1.0" encoding="UTF-8"> <data> <username>hello123</username> <startdate>01/01/2011</startdate> <enddate>06/01/2013</enddate> </data>
渴望data.xml之后
<?xml version="1.0" encoding="UTF-8"> <data> <username>hello123</username> <startdate>02/01/2011</startdate> <--- This will change <enddate>06/01/2013</enddate> </data>
main.java
public class main { public static void main(String[] args) { Calendar cal2 = null; String username = null; String startdate = null; String enddate = null; String date = null; String date_end = null; try { File data = new File("data.xml"); DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance(); DocumentBuilder dBuilder = dbFactory.newDocumentBuilder(); Document doc = dBuilder.parse(data); doc.getDocumentElement().normalize(); for (int i = 0; i < nodes.getLength(); i++) { Node node = nodes.item(i); if (node.getNodeType() == Node.ELEMENT_NODE) { Element element = (Element) node; username = getValue("username",element); startdate = getValue("startdate",element); enddate = getValue("enddate",element); } } date = startdate; //end date Date date_end = new SimpleDateFormat("MM/dd/yyyy",Locale.ENGLISH).parse(enddate); Calendar end_date_cal = Calendar.getInstance(); end_date_cal.setTime(date_end); // initial date Date date_int = new SimpleDateFormat("MM/dd/yyyy",Locale.ENGLISH).parse(date); cal2 = Calendar.getInstance(); cal2.setTime(date_int); //call the method updateDate(cal2); TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory.newTransformer(); DOMSource source = new DOMSource(doc); StreamResult result = new StreamResult(new File("data.xml")); transformer.transform(source,result); System.out.println("Update Successfully"); } } catch (Exception ex) { log.error(ex.getMessage()); ex.printstacktrace(); } } private static void updateDate(Calendar cal2){ cal2.add(Calendar.MONTH,1); //need to push it back to the calendar } private static String getValue(String tag,Element element) { NodeList nodes = element.getElementsByTagName(tag).item(0).getChildNodes(); Node node = (Node) nodes.item(0); return node.getNodeValue(); } private static void setValue(String tag,Element element,String input) { NodeList nodes = element.getElementsByTagName(tag).item(0).getChildNodes(); Node node = (Node) nodes.item(0); node.setTextContent(input); } }
解决方法
Java 8的Time API
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("M/d/yyyy"); LocalDate ld = LocalDate.parse("2/1/2013",formatter); System.out.println("From " + formatter.format(ld)); ld = ld.plusMonths(1); System.out.println("To " + formatter.format(ld));
哪个打印
From 2/1/2013 To 3/1/2013
但是,您永远不会将该值应用回XML文档.当我试图在你的previous question中演示时,你需要更改节点的textContent …
node.setTextContent(formatter.format(ld))
这就是为什么我建议使用xPath而不是走文档内容
例如…
import java.io.File; import java.io.IOException; import java.time.LocalDate; import java.time.format.DateTimeFormatter; import java.time.format.DateTimeParseException; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerException; import javax.xml.transform.TransformerFactory; import javax.xml.transform.TransformerFactoryConfigurationError; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory; import org.w3c.dom.DOMException; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.xml.sax.SAXException; public class UpdateXML { public static void main(String[] args) { try { DocumentBuilderFactory f = DocumentBuilderFactory.newInstance(); DocumentBuilder b = f.newDocumentBuilder(); Document doc = b.parse(new File("Data.xml")); XPath xPath = XPathFactory.newInstance().newXPath(); Node startDateNode = (Node) xPath.compile("/data/startdate").evaluate(doc,XPathConstants.NODE); startDateNode.setTextContent(addMonthTo(startDateNode.getTextContent())); xPath = XPathFactory.newInstance().newXPath(); Node endDateNode = (Node) xPath.compile("/data/enddate").evaluate(doc,XPathConstants.NODE); endDateNode.setTextContent(addMonthTo(endDateNode.getTextContent())); Transformer tf = TransformerFactory.newInstance().newTransformer(); tf.setoutputProperty(OutputKeys.INDENT,"yes"); tf.setoutputProperty(OutputKeys.METHOD,"xml"); tf.setoutputProperty("{http://xml.apache.org/xslt}indent-amount","4"); DOMSource domSource = new DOMSource(doc); StreamResult sr = new StreamResult(new File("AData.xml")); tf.transform(domSource,sr); } catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException | DOMException | TransformerFactoryConfigurationError | IllegalArgumentException | TransformerException exp) { exp.printstacktrace(); } } public static String addMonthTo(String value) { String patterns[] = {"M/d/yyyy","M/dd/yyyy","MM/d/yyyy","MM/dd/yyyy"}; LocalDate ld = null; for (String pattern : patterns) { try { ld = LocalDate.parse(value,DateTimeFormatter.ofPattern(pattern)); break; } catch (DateTimeParseException exp) { } } if (ld == null) { throw new DateTimeParseException("Could not parse " + value + " with available patterns",value,-1); } ld = ld.plusMonths(1); return DateTimeFormatter.ofPattern("MM/dd/yyyy").format(ld); } }
哪个…
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <data> <username>admin</username> <password>12345</password> <interval>1</interval> <timeout>90</timeout> <startdate>1/1/2013</startdate> <enddate>06/01/2013</enddate> <ttime>1110</ttime> </data>
并输出……
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <data> <username>admin</username> <password>12345</password> <interval>1</interval> <timeout>90</timeout> <startdate>02/01/2013</startdate> <enddate>07/01/2013</enddate> <ttime>1110</ttime> </data>
i want the startdate 6 months earlier then the enddate
Java 8
String endDateValue = "07/01/2013"; DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/dd/yyyy"); LocalDate endDate = LocalDate.parse(endDateValue,formatter); LocalDate startDate = endDate.minusMonths(6); String startDateValue = formatter.format(startDate);
日历
我更喜欢Joda-Time,但是
String endDateValue = "07/01/2013"; SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy"); Date endDate = sdf.parse(endDateValue); Calendar cal = Calendar.getInstance(); cal.setTime(endDate); cal.add(Calendar.MONTH,-6); Date startDate = cal.getTime(); String startDateVaue = sdf.format(startDate);
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