1、config对象的使用
1）xml 文件（web.xml）
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <welcome-file-list> <welcome-file>/showConfig.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>showConfig</servlet-name> <!-- jsp文件的路径--> <jsp-file>/showConfig.jsp</jsp-file> <!-- 初始参数列表--> <init-param> <!-- 参数以名称-值的方式存储--> <param-name>param1</param-name> <param-value>1</param-value> </init-param> </servlet> <servlet-mapping> <!-- 定义servlet的访问路径--> <servlet-name>showConfig</servlet-name> <url-pattern>/showConfig.jsp</url-pattern> </servlet-mapping> </web-app>
2）jsp 文件（showConfig.jsp）
<%-- Created by IntelliJ IDEA. User: Administrator Date: 2019/9/24 Time: 19:28 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>展示config中的初始参数</title> </head> <body> <%--根据名称获取初始参数的值--%> <%="param1's value = " + config.getInitParameter("param1")%><br /> <%--获取servlet的名称--%> <%="servlet name: " + config.getServletName()%> </body> </html>
2、session对象的使用
1）jsp 文件（index.jsp、setSession.jsp 和 welcome.jsp）
①index.jsp
<%-- Created by IntelliJ IDEA. User: Administrator Date: 2019/9/24 Time: 19:41 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>提交用户信息</title> </head> <body> <form action="setSession.jsp" method="post"> 用户名：<input type="text" name="username" /> 密码：<input type="password" name="userpwd"/> <input type="submit" value="提交"/> </form> </body> </html>
②setSession.jsp
<%-- Created by IntelliJ IDEA. User: Administrator Date: 2019/9/24 Time: 19:44 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>设置session属性的界面</title> </head> <body> <% String username = request.getParameter("username"); String userpwd = request.getParameter("userpwd"); if (username != null && userpwd != null) { if (userpwd.equals("admin")) { session.setAttribute("username", username); response.sendRedirect("welcome.jsp"); } else { response.sendRedirect("index.jsp"); } } else { response.sendRedirect("index.jsp"); } %> </body> </html>
③welcome.jsp
<%-- Created by IntelliJ IDEA. User: Administrator Date: 2019/9/24 Time: 19:47 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>欢迎登陆</title> </head> <body> <% out.print("欢迎 " + session.getAttribute("username")); out.print(" 登陆！"); %> </body> </html>