【JSTL】--测试EL表达式--drp212~
JstlElServlet:
/**
*
*/
package com.bjpowrnode.jstl;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* @ClassName:JstlElServlet
* @Description:测试EL表达式
* @author wm
* @date 2016年2月14日下午8:45:38
*/
public class JstlElServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//普通字符串
request.setAttribute("hello", "Hello World");
//结构
Group group =new Group();
group.setName("动力节点drp 603班");
User user=new User();
user.setUsername("张三");
user.setAge(23);
user.setGroup( group);
request.setAttribute("user", user);
//Map
Map map=new HashMap();
map.put("k1", "v1");
map.put("k2", "v2");
request.setAttribute("map", map);
//字符串数组
String[] strArray=new String[]{"a","b","c"};
request.setAttribute("str_array", strArray);
//对象数组
User[] users=new User[10];
for (int i=0;i<users.length;i++){
users[i]=new User();
users[i].setUsername("张三"+i);
}
request.setAttribute("users",users);
//List
List userList=new ArrayList();
for(int i =0;i<10;i++){
User usr=new User();
usr.setUsername("李四" +i);
userList.add(usr);
}
request.setAttribute("userList",userList);
//empty
request.setAttribute("v2","" );
request.setAttribute("v3", new ArrayList());
request.setAttribute("v4", "123456");
request.setAttribute("v5", null);
request.getRequestDispatcher("/jstl_el.jsp").forward(request, response);;
}
}
jstl_el.jsp
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<!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=GB18030">
<title>Insert title here</title>
</head>
<body>
<h1>测试EL表达式</h1>
<hr>
<li>普通字符串</li><br>
hello(jsp脚本):<%=request.getAttribute("hello") %></br>
hello(El表达式：语法：$和{}:${hello}<br>
hello(el表达式，el内置对象， pageScope,requestScope,sessionScope,applicationScope )<br>
如果不指定范围，它的搜索范围就是pageScope~applicationScope():${requestScope.hello}<br>
hello(el表达式，从session中取得)：${sessionScope.hello}<br>
<p>
<li>结构,采用。进行导航，或称为存取器</li><br>
姓名：${user.username}<br>
年龄：${user.age }<br>
所属：${user.group.name}<br>
</p>
<p>
<li>Map取值</li><br>
map.k1:${map.k1}<br>
map.k2:${map.k2}<br>
</p>
<p>
<li>字符串数组:采用[]下标</li><br>
strArray[1]:${str_array[1] }<br>
<p>
<li>对象数组：采用[]下标</li>
users[5].username:${users[5].username }<br>
<p>
<li>list,采用[] 下标</li>
userList[6].username:${userList[6].username }<br>
<p>
<li>el表达式对运算符的支持</li>
1+1= ${1+1 }<br>
10/5= ${10/5}<br>
10 div 5=${10 div 5 }<br>
10%3=${10%3 }<br>
10 mod 3=${10 mod 3 }<br>
<!--
==/eq
!=/ne
</lt
>/gt
&&/and
||/or
!/not
//div
%/mod
-->
<p>
<li>测试empty</li><br>
v1:${empty v1 }<br>
v2:${empty v2 }<br>
v3:${empty v3 }<br>
v4:${empty v4 }<br>
v5:${empty v5 }<br>
</body>
</html>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
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_3_0.xsd">
<servlet>
<servlet-name>JstlElServlet</servlet-name>
<servlet-class>com.bjpowrnode.jstl.JstlElServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>JstlElServlet</servlet-name>
<url-pattern>/servlet/JstlElServlet</url-pattern>
</servlet-mapping>
</web-app>
Group.java
/**
*
*/
package com.bjpowrnode.jstl;
/**
* @ClassName:Group
* @Description:TODO
* @author wm
* @date 2016年2月15日上午9:41:01
*/
public class Group {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
User.java
/**
*
*/
package com.bjpowrnode.jstl;
/**
* @ClassName:User
* @Description:TODO
* @author wm
* @date 2016年2月15日上午9:42:15
*/
public class User {
private String username1;
private int age;
private Group group;
public String getUsername() {
return username1;
}
public void setUsername(String username1) {
this.username1 = username1;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Group getGroup() {
return group;
}
public void setGroup(Group group) {
this.group = group;
}
}
感触：学一个东西，要小范围的系统的学，总结一下EL对常用的Map.list.数组的读取，80%学到了就可以了。这样应用级别的入门级别就ok了。
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