JavaWeb_(SSH)使用Servlet实现用户的登陆

Posted 2021-02-11 Cynical丶Gary

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了JavaWeb_(SSH)使用Servlet实现用户的登陆相关的知识，希望对你有一定的参考价值。

　　JavaWeb_(Struts2框架)使用Struts框架实现用户的登陆　　传送门

　　JavaWeb_(Struts2框架)Servlet与Struts区别　　传送门

　　mysql数据库中存在Gary用户，密码为123；第一次登陆时输入错误的密码1234后页面重定向，并输出错误的提示信息，第二次登陆时输入正确的密码，页面跳转到index.jsp中

　　c3p0-config.xml链接本地数据库

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>

    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///strutstest</property>
        <property name="user">root</property>
        <property name="password">123456</property>
        <property name="initialPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>


    <named-config name="oracel">
        <property name="driverClass">oracle.jdbc.driver.OracleDriver</property>
        <property name="jdbcUrl">jdbc:oracle:thin:@//192.168.40.128/orcl</property>
        <property name="user">scott</property>
        <property name="password">scott</property>
    </named-config>


</c3p0-config>

c3p0-config.xml

package com.Gary.web;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.sql.SQLException;

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 org.apache.commons.beanutils.BeanUtils;

import com.Gary.domain.User;
import com.Gary.service.UserService;

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        User user = new User();
        //封装user对象
        try {
            BeanUtils.populate(user, request.getParameterMap());
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        UserService userService = new UserService();
        //传递数据，判断数据库是否有user
        boolean success = false;
        try {
            success = userService.findUser(user);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        if(success) {
            //存在用户，登陆成功重定向到index.html
            response.sendRedirect(request.getContextPath()+"/index.html");
        }else {
            request.setAttribute("error", "用户名或密码错误！！");
            //不存在,转发到login.jsp
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);
    }

}

LoginServlet.java

package com.Gary.web;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.sql.SQLException;

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 org.apache.commons.beanutils.BeanUtils;

import com.Gary.domain.User;
import com.Gary.service.UserService;

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        User user = new User();
        //封装user对象
        try {
            BeanUtils.populate(user, request.getParameterMap());
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        UserService userService = new UserService();
        //传递数据，判断数据库是否有user
        boolean success = false;
        try {
            success = userService.findUser(user);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        if(success) {
            //存在用户，登陆成功重定向到index.html
            response.sendRedirect(request.getContextPath()+"/index.html");
        }else {
            request.setAttribute("error", "用户名或密码错误！！");
            //不存在,转发到login.jsp
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        doGet(request, response);
    }

}

UserService.java

package com.Gary.domain;

public class User {

    private String username;
    private String password;
    
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
    
    
}

User.java

package com.Gary.dao;

import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;

import com.Gary.domain.User;
import com.yl.lain.utils.C3p0DataSourceUtils;

public class UserDao {

    public User findUser(User user) throws SQLException {
        
        QueryRunner runner = new QueryRunner(C3p0DataSourceUtils.getDataSource());
        String sql = "select * from user where username = ? and password = ?";
        return runner.query(sql, new BeanHandler<User>(User.class),user.getUsername(),user.getPassword());
        
    }

}

UserDao.java

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>

<head>
<meta charset="UTF-8">

<link rel="stylesheet" href="css/head.css" />
<link rel="stylesheet" type="text/css" href="css/login.css" />
</head>

<body>
    <div class="dvhead">
        <div class="dvlogo">
            <a href="index.html">你问我答</a>
        </div>
        <div class="dvsearch">10秒钟注册账号，找到你的同学</div>
        <div class="dvreg">
            已有账号，立即&nbsp;<a href="login.html">登录</a>
        </div>
    </div>
    <section class="sec">
        <form action="${pageContext.request.contextPath }/login" method="post">
            <div class="register-box">
                <label for="username" class="username_label"> 用 户 名 <input maxlength="20" name="username" type="text" placeholder="您的用户名和登录名" />
                </label>
                <div class="tips"></div>
            </div>
            <div class="register-box">
                <label for="username" class="other_label"> 设 置 密 码 <input maxlength="20" type="password" name="password" placeholder="建议至少使用两种字符组合" />
                </label>
                <div class="tips"></div>
            </div>
            <div class="arguement">
                <input type="checkbox" id="xieyi" /> 阅读并同意 <a href="javascript:void(0)">《你问我答用户注册协议》</a> <a href="register.html">没有账号,立即注册</a>
                <div class="tips" style="color: red">${error }</div>
            </div>
            <div class="submit_btn">
                <button type="submit" id="submit_btn">立 即 登录</button>
            </div>
        </form>
    </section>
    <script src="js/index.js" type="text/javascript" charset="utf-8"></script>
</body>

　　项目结构

　　数据库中用户数据

实现过程

　　通过c3p0-config.xml链接本地数据库

        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///strutstest</property>
        <property name="user">root</property>
        <property name="password">123456</property>

　　web层接受由login.jsp页面的表单/login请求

        <form action="${pageContext.request.contextPath }/login" method="post">
            <div class="register-box">
                <label for="username" class="username_label"> 用 户 名 <input maxlength="20" name="username" type="text" placeholder="您的用户名和登录名" />
                </label>
                <div class="tips"></div>
            </div>
            <div class="register-box">
                <label for="username" class="other_label"> 设 置 密 码 <input maxlength="20" type="password" name="password" placeholder="建议至少使用两种字符组合" />
                </label>
                <div class="tips"></div>
            </div>
            <div class="arguement">
                <input type="checkbox" id="xieyi" /> 阅读并同意 <a href="javascript:void(0)">《你问我答用户注册协议》</a> <a href="register.html">没有账号,立即注册</a>
                <div class="tips" style="color: red">${error }</div>
            </div>
            <div class="submit_btn">
                <button type="submit" id="submit_btn">立 即 登录</button>
            </div>
        </form>

　　在domain层中创建用户User实体

    private String username;
    private String password;

package com.Gary.domain;

public class User {

    private String username;
    private String password;
    
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
    
    
}

User.java

　　web层LoginServlet.java处理用户登陆逻辑,由servlet层去调用dao层返回数据库中查询用户信息

    public User findUser(User user) throws SQLException {
        
        QueryRunner runner = new QueryRunner(C3p0DataSourceUtils.getDataSource());
        String sql = "select * from user where username = ? and password = ?";
        return runner.query(sql, new BeanHandler<User>(User.class),user.getUsername(),user.getPassword());
        
    }

　　dao层得到用户信息后传递给servlet层，servlet层获得user对象后传递给web层

　　web层中判断是否有用户信息，如果有，那么用户登陆成功后将页面重定向到index.html，否则跳转到login.jsp并显示错误的提示信息(将error封装到request域中在login.jsp中使用${error}标签将信息提示出来)　　

　　web层接受到login的dopost请求后调用doGet请求的逻辑处理

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        User user = new User();
        //封装user对象
        try {
            BeanUtils.populate(user, request.getParameterMap());
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        UserService userService = new UserService();
        //传递数据，判断数据库是否有user
        boolean success = false;
        try {
            success = userService.findUser(user);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        if(success) {
            //存在用户，登陆成功重定向到index.html
            response.sendRedirect(request.getContextPath()+"/index.html");
        }else {
            request.setAttribute("error", "用户名或密码错误！！");
            //不存在,转发到login.jsp
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

以上是关于JavaWeb_(SSH)使用Servlet实现用户的登陆的主要内容，如果未能解决你的问题，请参考以下文章

JavaWeb_Servlet篇_01

JavaWeb03_Servlet

JavaWeb_Servlet篇_01

JavaWeb_(Spring框架)用户登陆Spring整合到Servlet中