项目创建:
IDEA 创建 Servlet 项目详细步骤:https://www.jianshu.com/p/386a79d16e05
导入 mysql 驱动包:
Java MySQL 连接:https://eslsuwen.github.io/2019/06/02/Java-MySQL/
1. 创建测试数据
接下来我们在 MySQL 中创建 usersdb 数据库,并创建 user 数据表,表结构如下:
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CREATE TABLE `user` ( `name` char(20) NOT NULL DEFAULT ‘‘ COMMENT ‘name‘, `password` char(10) NOT NULL DEFAULT ‘‘ COMMENT ‘password‘ ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;
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插入一些数据:
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INSERT INTO `user` VALUES ( ‘admin‘, ‘admin‘ ), ( ‘ guest ‘, ‘ 123456 ‘ ), ( ‘ guest1 ‘, ‘ 123 ‘ );
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2. 创建登录 jsp 文件
在 web 目录下创建 login.jsp :
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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>登录</title> </head> <body> <div class="login" style="text-align:center;"> <fieldset> <legend>用户登录</legend> <br/> <form action="login" method="post" name="login"> 用户名:<input type="text" name="username"/> <br/> <br/> 密 码:<input type="password" name="password"/> <br/> <br/> <input type="submit" value="登录"/> </form> </fieldset> </div>
</body> </html>
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3. 创建登录 servlet 处理登录请求
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package login;
import database.JdbcOp;
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 javax.servlet.http.HttpSession; import java.io.IOException; import java.io.PrintWriter; import java.sql.ResultSet;
@WebServlet("/login") public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 一般都会在doGet()方法中调用doPost()方法,或者在doPost()方法中调用doGet()方法 doPost(request, response); }
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 设置编码格式,可以防止乱码出现 response.setContentType("text/html; charset=utf-8"); response.setCharacterEncoding("utf-8"); request.setCharacterEncoding("utf-8"); // 获取用户提交过来的用户名和密码,是通过表单中input的name属性获取的 String username = request.getParameter("username"); String password = request.getParameter("password"); String isSignUp = request.getParameter("isSignUp"); PrintWriter out = response.getWriter(); System.out.println(username + ": " + password + " isSignUp: " + isSignUp); // 获取输出流,用户显示信息,也可以用转发或者重定向 PrintWriter pw = response.getWriter();
try { JdbcOp jdbc = new JdbcOp(); jdbc.open("usersdb"); ResultSet rs = jdbc.executeQuery("select * from users");
while (rs.next()) { String nm = rs.getString("name"); String pd = rs.getString("password"); System.out.println("username: " + nm + " password: " + pd);
if (nm.equals(username) && pd.equals(password)) { HttpSession session = request.getSession(); //将数据存储到session中 session.setAttribute("isLogin", "true"); session.setAttribute("username", username);
out.print("<script language=‘javascript‘>alert(‘You login successful ! 你已成功登录!out.print‘);window.location.href=‘test.jsp‘;</script>"); out.flush(); out.close(); } } jdbc.close(); } catch (Exception e) { e.printStackTrace(); } pw.write("login fail"); out.print("<script language=‘javascript‘>alert(‘please login first 登陆信息输入有误!‘);window.location.href=‘login.jsp‘;</script>"); out.flush(); out.close(); }
}
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4. 运行项目
输入正确的账号密码:
账号密码验证失败: