Java

一、Java部分：Jstl:<%@ taglib prefix="c" uri="/jsp/jstl/core"%>1、页面分割字段：‘$fn{fn:substring(字段，开始位置，fn：indexof(字段，’分隔符’))}’2、Js中获取style的属性时例如：Background-color 区分大小写backgroundColor3、重定向与转发的区别：重定向（Redirect）：浏览器地址会变，目的任意，转发（forward）：同一个应用的内部组件才能用转发，可以共享request 对象，效率高4、解析xml1.解析xml: byte xmlByte[] 转换成map集合4.1、DOM解析：<?xml version="1.0" encoding="ISO-8859-1"?><bookstore><book category="children"><title lang="en">Harry Potter</title><author>J K. Rowling</author><year>2005</year><price>29.99</price></book><book category="cooking"><title lang="en">Everyday Italian</title><author>Giada De Laurentiis</author><year>2005</year><price>30.00</price></book><book category="web"><title lang="en">Learning XML</title><author>Erik T. Ray</author><year>2003</year><price>39.95</price></book><book category="web"><title lang="en">XQuery Kick Start</title><author>James McGovern</author><author>Per Bothner</author><author>Kurt Cagle</author><author>James Linn</author><author>VaidyanathanNagarajan</author><year>2003</year><price>49.99</price></book></bookstore>新建Java类，解析如下：packagecom.example.xml.dom;importjava.io.File;importjavax.xml.parsers.DocumentBuilder; importjavax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.NodeList;public class DomTest1{public static void main(String[] args) throws Exception{// step 1:获得DOM解析器工厂// 工厂的作用是创建具体的解析器DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();// step 2：获得具体的dom解析器DocumentBuilderdb = dbf.newDocumentBuilder();// step 3:解析一个xml文档，获得Document对象（根节点）// 此文档放在项目目录下即可Document document = db.parse(new File("books.xml"));// 根据标签名访问节点NodeList list = document.getElementsByTagName("book");System.out.println("list length: " + list.getLength());// 遍历每一个节点for (int i = 0; i <list.getLength(); ++i){System.out.println("----------------------");// 获得元素，将节点强制转换为元素Element element = (Element) list.item(i);// 此时element就是一个具体的元素// 获取子元素：子元素title只有一个节点，之后通过getNodeValue方法获取节点的值String content0 = element.getElementsByTagName("title").item(0).getNodeValue();System.out.println(content0);// 此处打印出为null// 因为节点getNodeValue的值永远为null// 解决方法：加上getFirstChild()String content = element.getElementsByTagName("title").item(0).getFirstChild().getNodeValue();System.out.println("title: " + content);// 此处打印出书名// 后面类似处理即可：content = element.getElementsByTagName("author").item(0).getFirstChild().getNodeValue();System.out.println("author: " + content);content = element.getElementsByTagName("year").item(0).getFirstChild().getNodeValue();System.out.println("year: " + content);content = element.getElementsByTagName("price").item(0).getFirstChild().getNodeValue();System.out.println("price: " + content);}}}4.2、sax解析Xml:<?xml version="1.0" encoding="UTF-8"?><emps><emp id="1"><name>zhangsan</name><sex>man</sex></emp><emp id="2"><name>lisi</name><sex>women</sex></emp></emps>Java部分：importjavax.xml.parsers.SAXParser;importjavax.xml.parsers.SAXParserFactory;importorg.xml.sax.Attributes;importorg.xml.sax.helpers.DefaultHandler;public class SAXParserTest extends DefaultHandler{publicSAXParserTest() {super();}public void startElement(String uri,StringlocalName,StringqName,Attributesattr){ if(attr.getLength()>0){for(int i = 0;i<attr.getLength();i++){System.out.println(attr.getQName(i)+" = "+attr.getValue(i));}}}public static void main(String[] args){try{//实例化用于分析的工厂SAXParserFactory factory = SAXParserFactory.newInstance();//实例化分析类SAXParser parser = factory.newSAXParser();SAXParserTest handler = new SAXParserTest();parser.parse("example.xml",handler);}catch(Exception e){System.out.println(e.toString());}}}二、获取元素块名字属性值<?xml version="1.0"?><?xml-stylesheet type="text/xsl"?><property><name>search.response.default.numrows</name><value>10</value><description>The default number of rows to return if none is specified.</description></property><property><name>searcher.response.maxage</name><value>86400</value><description>The maxage of a response in ed in caching headers.</description></property></configuration>Java部分：importjavax.xml.parsers.SAXParser;importjavax.xml.parsers.SAXParserFactory;importorg.xml.sax.Attributes;importorg.xml.sax.helpers.DefaultHandler;importorg.xml.sax.SAXException;importjava.util.Properties;public class SAXParserTest2 extends DefaultHandler{private Properties props; //用于存放名字属性对(key-value)private String currentName; //当前扫描到的键值private StringBuffercurrentValue = new StringBuffer(); //当前名字对应的值private String Name,Value;//键值对public SAXParserTest2(){super();this.props=new Properties();}public void startElement(String uri,StringlocalName,StringqName,Attributesattr){currentValue.delete(0,currentValue.length());this.currentName=qName;}//碰到节点开始和结束之间的字符<element>***</element>public void characters(char[] ch,intstart,int length) throws SAXException{currentValue.append(ch,start,length);}//碰到节点结束</element>public void endElement(String uri,StringlocalName,StringqName){String name=currentName,value=currentValue.toString().trim();if(name!=""&&value!="")System.out.println(name+"="+value);if(name=="name")Name=value;if(name=="value")Value=value;if(qName=="property")props.put(Name,Value);this.currentName="";currentValue.delete(0,currentValue.length());}public String getElementValue(String elementName){//elementValue:对应于elementName的节点的属性值String elementValue=null;elementValue=props.getProperty(elementName);returnelementValue;}public static void main(String[] args) {try{SAXParserFactory factory = SAXParserFactory.newInstance();SAXParser parser = factory.newSAXParser();SAXParserTest2 handler = new SAXParserTest2();parser.parse("nutch-default.xml",handler); System.out.println(handler.getEleme ntValue("searcher.response.maxage "));}catch(Exception e){System.out.println(e.toString());}}}1.2、servletServlet生命周期Servlet运行在Servlet容器中，其生命周期由容器来管理。