编写Servlet,验证用户登录,如果用户名与密码都为“admin”则验证通过,跳转欢迎页面,否则弹出提示信息“用户名或密码错误,请重新输入!”,点击“确定”后跳转至登录页面

java代码:(Test1)

package com.test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(urlPatterns={"/Test1"})
public class test1 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO 自动生成的方法存根
        req.setCharacterEncoding("gbk");
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter out = resp.getWriter();
        String user=req.getParameter("user");
        String pass = req.getParameter("pwd");
        if(user.equals("admin")&&pass.equals("admin")){
            out.println("欢迎登陆");
        }else{
            out.println("<script language='javascript'>alert('用户名或密码错误,请重新输入!')</script>");
            out.println("<script language='javascript'>window.location.href='/Servlet_work/Html1.html'</script>");
        }
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO 自动生成的方法存根
        doGet(req, resp);
    }
}

html代码:(html1)

<!DOCTYPE html>
<html>

    <head>
        <title>Html1.html</title>

        <meta name="keywords" content="keyword1,keyword2,keyword3">
        <meta name="description" content="this is my page">
        <meta name="content-type" content="text/html; charset=utf-8">

        <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
        <style>
            #home {
                width: 300px;
                height: 300px;
                margin: auto;
            }
            .dl1{
                clear: both;
            }
            .dl1 dt{
                float: left;
                
            }
            .dd1 dd{
                float: left;
            }
            h1{
                text-align: center;
            }
            #foot{
                text-align: center;
            }
        </style>
    </head>

    <body>
        <div id="home">
            <h1>用户登陆</h1>
            <form action="Test1" method="post">
                <dl class="dl1">
                    <dt>用户账号:</dt>
                    <dd><input type="text" name="user" /></dd>
                </dl>
                <dl class="dl1">
                    <dt>用户密码:</dt>
                    <dd><input type="passWord" name="pwd" /></dd>
                </dl>
                <div id="foot">
                <input type="submit" value="登陆"/>
                </div>
            </form>
        </div>
    </body>

</html>

运行截图:

备注:

在Servlet中实现页面中弹窗:

PrintWriter out = resp.getWriter();
 out.println("<script language='javascript'>alert('用户名或密码错误,请重新输入!')</script>");

在Servlet中实现页面的跳转:

 out.println("<script language='javascript'>window.location.href='/Servlet_work/Html1.html'</script>");
原文地址:https://www.cnblogs.com/a1045417817/p/7521202.html