03 el

本节讲述el表达式的用法。el表达式的引入是为了减少jsp中的java代码。

1、环境约束

  • idea2018.1.5
  • maven-3.0.5
  • jdk-8u162-windows-x64
  • servlet3.0

2、前提约束

3、操作步骤

  • 在servlet-test/src/main/java文件夹下创建net.wanho.servlet包
  • 在net.wanho.servlet包中创建ELServlet.java
package net.wanho.servlet;

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("/el")
public class ELServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setAttribute("request1", "request");
        req.getSession().setAttribute("session1", "session");
        req.getSession().getServletContext().setAttribute("application1", "application");
        req.getRequestDispatcher("/el.jsp").forward(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}
  • 在servlet-test/src/main/webapp文件夹下创建el.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%=request.getAttribute("request1")%><br/>
<%=request.getSession().getAttribute("session1")%><br/>
<%=request.getSession().getServletContext().getAttribute("application1")%><br/>
===============================================================<br/>
${request1}    or    ${requestScope.request1}<br/>
${session1}    or    ${sessionScope.session1}<br/>
${application1}    or    ${applicationScope.application1}<br/>
</body>
</html>

以上就是el在jsp中的使用。

posted @ 2020-04-01 17:42  张力的程序园  阅读(128)  评论(0)    收藏  举报