Go语言视频零基础入门到精通

javalearner · 发表于 2014-10-28 23:56:02

JSP EL
 部分




 一、
 JSP EL
 的运算符









 类型




 定义






 算术型




 + - * / div % mod






 逻辑型




 and && or || not !






 关系型




 == eq != ne > gt < lt >= ge <= le






 条件型




 a?b:c






 空




 empty








二、
 JSP EL
 的基本用法









 类型




 实例




 基本调用方法






 javaBeans




 ${user.username}



 ${user["username"]}



 ${user["username"]}




 user.getUsername()






 数组




 ${sport[1]}



 ${sport["1"]}



 ${sport["1"]}




 sport[1]






 List




 ${phone[2]}



 ${phone["2"]}



 ${phone["2"]}




 phone.get(2)






 Map




 ${phone.home}



 ${phone["home"]}



 ${phone["home"]}




 phone.get("home")








三、
 JSP EL
 的内容对象




 pageContext 当前页面上下文件对象
pageScope page对象
requestScope request对象
sessionScope session对象
applicationScope application对象
param 得到页面传来的参数
paramValues 得到页面传来的多个参数，返回一个数组
header 获取头信息
headerValues 获取头信息的值
cookie 获取cookie对象的值
initParam 获取设定初始的参数值








 例：



 <%=session.getAttribute("phone")%>

 等价于${sessionScope.phone}






四、如何设置
 JSP
 不使用
 JSP EL



 1
 、当前页面不要用
 JSP EL









 <%@page isELIgnored="true" %>




 2
 、整个
 web
 应用都不使用
 EL
 ，修改
 web.xml
 文件






 <
 web-app...
 >




 <
 jsp-config
 >




 <
 jsp-property-group
 >




 <
 url-pattern
 >*.jsp
 </
 url-pattern
 >




 <
 el-ignored
 >true
 </
 el-ignored
 >




 </
 jsp-property-group
 >




 </
 jsp-config
 >




 </
 web-app...
 >




五、实例




 1
 、基本运算符的实例



 <%@ page language="java" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
 <title>My JSP "elExample1.jsp" starting page</title>
 <meta http-equiv="pragma" content="no-cache">
 <meta http-equiv="cache-control" content="no-cache">
 <meta http-equiv="expires" content="0">
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
 <meta http-equiv="description" content="This is my page">
 
</head>
<body>
 
 ${10+10 } 
 ${10-10 } 
 ${10*10 } 
 ${10/10 } 
 ${10 div 10 } 
 ${10%10 } 
 ${10 mod 10 } 
 
 ${10+10 } 
 "$"{10+10 } 

 
 ${100>200 } 
 ${100 gt 200 } 
 ${100<200 } 
 ${100 lt 200 } 
 ${100>=200 } 
 ${100 ge 200 } 
 ${100<=200 } 
 ${100 le 200 } 
 ${100==200 } 
 ${100 eq 200 } 
 ${100 !=200 } 
 ${100 ne 200 } 
 
 ${"e" eq "h" } 
 ${"hit" > "him" } 

 
 ${(10>2) && (34>25) } 
 ${(10>2) and (34>25) } 
 ${(10>2) || (34>25) } 
 ${(10>2) or (34>25) } 
 ${!(10>2)} 
 ${not(10>2)} 

 
 <%
 pageContext.setAttribute("username",null);
 pageContext.setAttribute("password","");
 pageContext.setAttribute("city","北京");
 pageContext.setAttribute("date",new java.util.Date());
 %>
 
 ${empty username } 
 
 ${empty password } 
 
 ${empty city } 
 
 ${empty date } 

</body>
</html>








 2、用JSP EL读取JavaBean中的值



 <%@ page language="java" pageEncoding="UTF-8"%>
<%@ page import="java.util.*,com.meixin.beans.*"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
 <title>My JSP "elExample1.jsp" starting page</title>
 <meta http-equiv="pragma" content="no-cache">
 <meta http-equiv="cache-control" content="no-cache">
 <meta http-equiv="expires" content="0">
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
 <meta http-equiv="description" content="This is my page">
 
</head>
<body>

<jsp:useBean id="user" class="com.meixin.beans.User"></jsp:useBean>
<jsp:setProperty name="user" property="username" value="meixin"/>
<%
 //建立Profile对象，设置邮件地址
 Profile p = new Profile();
 p.setEmail("wnight88@sina.com");

 //将不同的电话存入Map中，并设置在p对象的属性中
 Map<String,String> phone = new HashMap<String,String>();
 phone.put("office","8383838");
 p.setPhone(phone);

 //建立地址对象，设置城市名
 Address address = new Address();
 address.setCity("北京");
 Address[] addresses = {address};
 p.setAddress(addresses);
 user.setProfile(p);
 %>
 
 
 ${user.username } 
 ${user["username"] } 
 ${user["username"] } 
 
 ${user.profile.phone.office } 
 ${user["rofile"]["phone"]["office"] } 
 
 ${user.profile.address[0].city } 
</body>
</html>









 以下为对象的JavaBean的内容



 1)Profile类




 package com.meixin.beans;
import java.util.Date;
import java.util.Map;
public class Profile
{
private String email;
private Date birthday;
private Address[] address;
private Map<String, String> phone;
public String getEmail()
{
 return email;
}
public void setEmail(String email)
{
 this.email = email;
}
public Date getBirthday()
{
 return birthday;
}
public void setBirthday(Date birthday)
{
 this.birthday = birthday;
}
public Address[] getAddress()
{
 return address;
}
public void setAddress(Address[] address)
{
 this.address = address;
}
public Map<String, String> getPhone()
{
 return phone;
}
public void setPhone(Map<String, String> phone)
{
 this.phone = phone;
}
}







 2)User类



 package com.meixin.beans;
public class User
{
private Long userID;
private String userName;
private String password;
private Profile profile;

public Long getUserID()
{
 return userID;
}
public void setUserID(Long userID)
{
 this.userID = userID;
}
public String getUserName()
{
 return userName;
}
public void setUserName(String userName)
{
 this.userName = userName;
}
public String getPassword()
{
 return password;
}
public void setPassword(String password)
{
 this.password = password;
}
public Profile getProfile()
{
 return profile;
}
public void setProfile(Profile profile)
{
 this.profile = profile;
}

}




 3)Address类



 package com.meixin.beans;
public class Address
{
private String city;
public String getCity()
{
 return city;
}
public void setCity(String city)
{
 this.city = city;
}
}




 3、实例：输出页面不同范围内属性的值
















 <%@ page language="java" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>

 <title>My JSP "elExample1.jsp" starting page</title>

 <meta http-equiv="pragma" content="no-cache">
 <meta http-equiv="cache-control" content="no-cache">
 <meta http-equiv="expires" content="0">
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
 <meta http-equiv="description" content="This is my page">
 

</head>

<body>
 <%
 pageContext.setAttribute("username","meixin");
 request.setAttribute("username","meixinRequest");
 session.setAttribute("username","meixinSession");
 application.setAttribute("username","meixinApplication");
 %>
 
 ${pageScope.username } 
 ${pageScope["username"] } 
 
 ${sessionScope.username } 
 
 ${requestScope.username } 
 
 ${applicationScope.username } 
 
 ${username } 

</body>
</html>





4、实例：param用于获取上一页面传递的参数值




 
${param.username} 
${param.password} 

















 5、实例：cookie用于获取cookie参数的值



 <%
 response.addCookie(new Cookie("username","meixin"));
%>

${cookie.user.value }











 6、实例：initParam用于获取web.xml中初始的参数值


 1)web.xml文件












 <?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaEE"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

<context-param>
 <param-name>repeat</param-name>
 <param-value>100</param-value>
</context-param>
 <welcome-file-list>
 <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>








 2)JSP EL代码




 ${initParam.repeat}

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