Person类
package cn.itcast.domain; import java.util.Date; public class Person { private String name; private Address address; public Person() { } public Person(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } }
Address类:
package cn.itcast.domain; public class Address { private String city; public String getCity() { return city; } public void setCity(String city) { this.city = city; } }
Servlet要么通过域带过来,对象带过来,集合带过来,所以,EL表达式取出元素的几种方式:
<%@page import="java.util.*"%> <%@page import="cn.itcast.domain.*"%> <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <% String data = "abcd"; request.setAttribute("data", data); %> ${data } <%--pageContext.findAttribute("data") page request session application --%> <br /> <% Person p = new Person(); p.setName("aaaa"); request.setAttribute("person", p); %> ${person.name } <%--pageContext.findAttribute("person") page request session application --%> <br /> <% Person p1 = new Person(); Address a = new Address(); a.setCity("成都"); p1.setAddress(a); request.setAttribute("p1", p1); %> ${p1.address.city } <br /> <% List<Person> list = new ArrayList<Person>(); list.add(new Person("aaa")); list.add(new Person("bbb")); list.add(new Person("ccc")); request.setAttribute("list", list); %> ${list[1].name } <br /> <% Map<String, Person> map = new HashMap<String, Person>(); map.put("aa", new Person("aaaaa")); map.put("bb", new Person("bbbbb")); map.put("cc", new Person("ccccc")); map.put("dd", new Person("ddddd")); map.put("11", new Person("eeeee"));//一般不以数字作为关键字,若要这么做那么EL表达式的写法为${map['11'].name} request.setAttribute("map", map); %> <!-- 以关键字去找集合的元素 --> ${map } <!-- 找到集合 --> <br /> ${map.aa } <!-- 用关键字找到对象 --> <br /> ${map.bb.name } <!-- 找到对象的name --> <br /> ${map['11'].name } <!-- 用EL表达式取数据一般是用.号,.号取不出数据时用[] --> <!-- Servlet要么通过域带过来,对象带过来,集合带过来 --> <br />${pageContext.request.contextPath } <!-- 获取当前Web应用的名称 --> <br /><a href="/Web/index.jsp" />点击</a> <!-- 一般不能这样写 --> <a href="${pageContext.request.contextPath }/index.jsp">点击</a> </body> </html>
JSTL标签遍历集合列表:
<%@page import="java.util.*"%> <%@page import="cn.itcast.domain.Person"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>JSTL标签遍历集合列表</title> </head> <body> <% List<Person> list = new ArrayList<Person>(); list.add(new Person("aaa")); list.add(new Person("bbb")); list.add(new Person("ccc")); request.setAttribute("list", list);//保存到request域中 %> <br /> <c:forEach var="person" items="${list }"> ${person.name }<br /> </c:forEach> <% Map<String, Person> map = new HashMap<String, Person>(); map.put("aa", new Person("aaaaa")); map.put("bb", new Person("bbbbb")); map.put("cc", new Person("ccccc")); map.put("dd", new Person("ddddd")); map.put("11", new Person("eeeee"));//一般不以数字作为关键字,若要这么做那么EL表达式的写法为${map['11'].name} request.setAttribute("map", map); %> <c:forEach var="entry" items="${map }"> ${entry.key }:${entry.value.name }<br /> </c:forEach> <!-- 代表用户登录 --> <c:if test="${user!=null }"> 欢迎您:${user.username } </c:if> <c:if test="${user==null }"> 用户名:<input type="text" name="username"><br /> 密 码:<input type="password" name="password"><br /> <input type="submit" value="登录" /> </c:if> </body> </html>
时间: 2024-11-09 01:59:56