<%@ 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);
}
转载于:https://www.cnblogs.com/lastingjava/p/9899032.html
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