Java 14 EL表达式

 

eljstl.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
    <h1>首页</h1>
<%--指令包含<%@ include file=""%> 翻译时还是-一个index.文件
标签包含翻译时出现多个x和index文件
--%>
    <jsp:include page="x.jsp"/>
    <hr>
    <p>一个jsp：${pageScope.x}</p>
    <p>请求：${requestScope.a}</p>
    <p>会话：${sessionScope.b}</p>
    <p>应用：${applicationScope.c}</p>
<%--结果同下--%> <%--  ${变量}   --%>
    <p>一个jsp:${x}</p>
    <p>请求:${a}</p>
    <p>会话:${b}</p>
    <p>应用:${c}</p>
    <p>取项目名:${pageContext.request.contextPath}</p>
    <a href="${pageContext.request.contextPath}/xxx">跳转</a>
    <p>欢迎:<strong>${user.usr_name}</strong>访问</p><%--点操作符--%> <%-- []操作符：${user["usr_name"]}--%>
</body>
</body>
</html>
<%--
>按照page -→request -→> session - > application （从低到高找）
的作用域顺序依次查找，找到即返回，最终找不到
返回null
--%>

ELJSLTServlet.java

package servlet;

import entity.User;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/ELFSLTServlet")
public class ELFSLTServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("a","1");
        request.getSession().setAttribute("b","2");
        request.getSession().setAttribute("user",new User(1,"张三","zs","123"));
        request.getServletContext().setAttribute("c","3");
        request.getRequestDispatcher("/jiaoxue/eljstl.jsp").forward(request,response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

 

 

posted @ 2023-08-29 11:17  OYそ  阅读(2)  评论(0)  编辑  收藏  举报