xml

XML 可扩展标记语言 ，是一种简单的数据存储语言，使用一系列简单的标签描述数据,使人们或者程序可以理解 ; 可读性强 灵活性高.

对44.txt文件中的内容进行提取，在这里提取Weather中所包含的内容

@H_404_14@import java.io.File; import java.io.IOException; import org.w3c.dom.Document; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; import org.w3c.dom.NamedNodeMap; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Node; public class FileXml { public static void main(String[] args) { File file =new File ("d:\\44.txt"); DocumentBuilderFactory dbf=DocumentBuilderFactory.newInstance(); try { DocumentBuilder db=dbf.newDocumentBuilder(); Document doc=db.parse(file); NodeList weathers=doc.getElementsByTagName("Weather"); for (int i = 0; i < weathers.getLength(); i++) { Node weather =weathers.item(i); /* NamedNodeMap map=weather.getAttributes(); System.out.println(map.getNamedItem(" ").getNodeValue());*/ for(Node node =weather.getFirstChild();node!=null;node=node.getNextSibling()) if(node.getNodeType()==node.ELEMENT_NODE){ System.out.println(node.getNodeName()); if(node.getFirstChild()!=null){ System.out.println(node.getFirstChild().getNodeValue()); } } } } catch (ParserConfigurationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

运行结果：

SAX

自定义解析器来对文件进行提取

@H_404_14@自己定义的一个文件解析器，重写了默认的方法 import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class MySAXHandle extends DefaultHandler{ @Override public void characters(char[] ch,int start,int length) throws SAXException { // TODO Auto-generated method stub super.characters(ch,start,length); System.out.println("标签内容 is "+new String(ch,length)); } @Override public void endDocument() throws SAXException { // TODO Auto-generated method stub super.endDocument(); System.out.println("文档结束"); } @Override public void endElement(String uri,String localName,String qName) throws SAXException { // TODO Auto-generated method stub super.endElement(uri,localName,qName); System.out.println("标签结束"); } @Override public void startDocument() throws SAXException { // TODO Auto-generated method stub super.startDocument(); System.out.println("文档开始 "); } @Override public void startElement(String uri,String qName,Attributes attributes) throws SAXException { // TODO Auto-generated method stub super.startElement(uri,qName,attributes); System.out.println("标签开始 name is "+qName); } }

对文件进行解析提取

@H_404_14@import java.io.File; import java.io.IOException; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.SAXException; public class FileSax { public static void main(String[] args) { File file=new File("d:\\44.txt"); SAXParserFactory factory=SAXParserFactory.newInstance(); try { SAXParser parser =factory.newSAXParser(); MySAXHandle handle=new MySAXHandle(); parser.parse(file,handle); } catch (ParserConfigurationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SAXException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }

运行结果为：

1. xml中 dom 树形结构一次性读到内存中，特点是简单快，但是只适用于小文件
2. sax 事件驱动 如果文件很大，不会全部读到内存中