request负责封装客户端请求，response封装的是服务器的响应重定向采用response.sendRedirect(url)实现，重定向行为发生于浏览器，地址栏地址改变转发采用request.getRequestDispatcher(url).forward(request, response)实现，转发行为发生于服务器，地址栏地址不改变<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body><form action="controller.jsp" method="post"><table><tr><td>用户名</td><td><input type="text" name="userName"></td></tr><tr><td>密码</td><td><input type="password" name="Password"></td></tr><tr><td><input type="submit" value="提交"></td></tr></table></form></body></html> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body><%String userName = request.getParameter("userName");String passWord = request.getParameter("Password");if(userName.equals("sa") && passWord.equals("123")){//1.通过响应告诉浏览器该请求这样一个地址//2.浏览器访问指定url 302代表告诉浏览器该重定向一个URL了response.sendRedirect("welcome.jsp?userName="+userName); //方法2：转发采用RequestDispatcher rd =request.getRequestDispatcher("welcome.jsp");rd.forward(request, response);}else{out.print("用户名或密码不正确！！！");}%></body></html> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><%//浏览器发起了两次请求 导致第一次请求 失败//1.当第一次请求失败的时候，把数据进行保存 使用数据作为参数来发起第二次请求//2.只发出一次请求 完成页面跳转%><body>您好<%=request.getParameter("userName") %>！欢迎访问！！！</body></html>
运行效果：
利用链接形式传参：
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body><a rel="external nofollow" href="result.jsp?color=黄色">黄色</a><a rel="external nofollow" href="result.jsp?color=白色">白色</a><a rel="external nofollow" href="result.jsp?color=红色">红色</a><a rel="external nofollow" href="result.jsp?color=黑色">黑色</a><a rel="external nofollow" href="result.jsp?color=蓝色">蓝色</a><a rel="external nofollow" href="result.jsp?color=紫色">紫色</a></body></html> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta charset="UTF-8"><title>Insert title here</title></head><body>您所选择的是<%=request.getParameter("color") %></body></html>