<%@ page language="java" pageEncoding="utf-8" import="com.study.vo.*,java.util.*" %>
<html>
<head>
</head>
<body>
<h2>使用普通方法获得作用域对象</h2>
<b><%=request.getParameter("name")%></b><br/>
<b><%=request.getAttribute("str")%></b><br/>
<b><%=((User)request.getAttribute("user")).getAddress().getAddr()%></b><br/>
<b><%=((ArrayList<User>)request.getAttribute("list")).get(0).getAddress().getAddr() %></b><br/>
<b><%=((HashMap<String,User>)request.getAttribute("map")).get("user").getAddress().getAddr()%></b>
<hr/>
<h2>使用EL表达示获得作用域对象(优点：不用导包，阅读方法，代码更少)</h2>
<b>${param.name}</b><br/>
<b>${str}</b><br/>
<b>${user.address.addr}</b><br/>
<b>${list[0].address.addr}</b><br/>
<b>${map.user.address.addr}</b><br/>
<h2>EL表达式获取对象默认顺序</h2>
<%
pageContext.setAttribute("hello","pagecontext");
request.setAttribute("hello","request");
session.setAttribute("hello","session");
application.setAttribute("hello","application");
%>
<b>pageContext-->request-->session-->application</b><br>
<b>${pageScope.hello}</b><br>
<b>${requestScope.hello}</b><br>
<b>${sessionScope.hello}</b><br>
<b>${applicationScope.hello}</b><br>
<h2>EL表达式的算术运算</h2>
<strong>不支持字符串连接</strong><br/>
${1+2}--${1-2}--${1>2}--${1==2?0:0}--${1+"2"}
<h2>判断是否为空</h2>
<b>${empty str}</b>
<b>${empty test}</b>
<h2>获得请求头数据 heard(了解)</h2>
<b>${header }</b><br>
<b>${header["cookie"] }</b><br>
<b>${headerValues["cookie"]}</b>
<h2>获得cookie数据</h2>
<b>${cookie }</b><br>
<b>${cookie.JSESSIONID }</b><br>
<b>${cookie.JSESSIONID.name }</b><br>
<b>${cookie.JSESSIONID.value }</b><br>
</body>
</html>
@Override
public void service(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
request.setAttribute("str","javase");
User u=new User(1, "javase", "javaee", "javame", new Address("china"));
request.setAttribute("user",u);
List<User> list=new ArrayList<User>();
list.add(u);
request.setAttribute("list", list);
Map<String,User> map=new HashMap<String,User>();
map.put("user",u);
request.setAttribute("map",map);
request.getRequestDispatcher("/ELStudy.jsp").forward(request, response);
}
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