EL表达式（二）运算符
运算符"."和"[]": "."能做的"[]"也能做，"[]"能做的"."不一定能做。java不识别的用"[]"
算数运算符：+,-,*,/或div,%或mod
关系运算符：==或eq,!=或ne,<或lt,>或gt,<=或le,>=或ge
逻辑运算符： &&或and , ||或or , !或not
其他运算符： empty 当判断的对象为null或空字符串否返回true，集合对象部位null，但无元素是返回true , ?: 三元运算符(${a?b:c})
EL表达式不支持字符串链接
1. Java
1 package cn.gs.ly.mvc.domain; 2 3 import java.util.Date; 4 5 public class Person { 6 private String name; 7 private String gender; 8 private boolean married; 9 private Date birthday; 10 private Address address = new Address(); 11 12 public Person() { 13 14 } 15 16 public Person(String name, String gender, boolean married) { 17 super(); 18 this.name = name; 19 this.gender = gender; 20 this.married = married; 21 } 22 23 24 public Address getAddress() { 25 return address; 26 } 27 28 public void setAddres(Address address) { 29 this.address = address; 30 } 31 32 public String getName() { 33 return name; 34 } 35 public void setName(String name) { 36 this.name = name; 37 } 38 public String getGender() { 39 return gender; 40 } 41 public void setGender(String gender) { 42 this.gender = gender; 43 } 44 public boolean isMarried() { 45 return married; 46 } 47 public void setMarried(boolean married) { 48 this.married = married; 49 } 50 public Date getBirthday() { 51 return birthday; 52 } 53 public void setBirthday(Date birthday) { 54 this.birthday = birthday; 55 } 56 57 }
2. jsp
1 <%@page import="java.util.HashMap"%> 2 <%@page import="java.util.Map"%> 3 <%@page import="java.util.ArrayList"%> 4 <%@page import="java.util.List"%> 5 <%@page import="cn.gs.ly.mvc.domain.Person"%> 6 <%@ page language="java" contentType="text/html" pageEncoding="UTF-8"%> 7 <!DOCTYPE html> 8 <html> 9 <head> 10 <title>Insert title here</title> 11 </head> 12 <body> 13 <% 14 pageContext.setAttribute("num1", "100"); 15 pageContext.setAttribute("num2", "20"); 16 %> 17 加法:${num1+num2 }<hr/> 18 减法:${num1-num2 }<hr/> 19 乘法:${num1*num2 }<hr/> 20 除法:${num1/num2 }或${num1 div num2 }<hr/> 21 取模:${num1%num2 }或${num1 mod num2 }<hr/> 22 23 等于:${num1==num2 }或${num1 eq num2 }<hr/> 24 不等于:${num1!=num2 }或${num1 ne num2 }<hr/> 25 大于:${num1>num2 }或${num1 gt num2 }<hr/> 26 小于:${num1<num2 }或${num1 lt num2 }<hr/> 27 大于等于:${num1>=num2 }或${num1 ge num2 }<hr/> 28 小于等于:${num1<=num2 }或${num1 le num2 }<hr/> 29 30 实例化前:${empty p}<hr/> 31 实例化前:${empty ""}<hr/> 32 <jsp:useBean id="p" class="cn.gs.ly.mvc.domain.Person"></jsp:useBean> 33 实例化后:${empty p}<hr/> 34 实例化后:${empty ""}<hr/> 35 实例化后:${empty " "}<hr/> 36 37 <% 38 List list = new ArrayList(); 39 list.add("a"); 40 41 pageContext.setAttribute("list", list); 42 43 session.setAttribute("user", "liuchao"); 44 pageContext.setAttribute("gender", "0");// 0男1女 45 %> 46 list集合:${empty list }<hr/> 47 user:${empty sessionScope.user?"请登录":"欢迎" }${user }<hr/> 48 性别:${gender==0?"男":"女" }<hr/> 49 50 </body> 51 </html>
3. 运行结果
