【JavaWeb】Html、Servlet、JDBC实现页面登录

---

任务概述

任意一个项目或 APP，必不可少的就是登录模块，用户登录成功或失败，跳转到不同结果页面，现在接到组长分配的任务，需要给项目添加一个登录模块，要求贴切真实网站需求，页面有表单验证，后台连接数据库真实判断，跳转到不同页面给用户提示

---

具体需求

编写登录界面并进行表单验证

通过servlet将数据从客服端发送到服务器

通过java代码操作数据库，判断用户名和密码是否正确

---

涉及知识点

1、sql语言及基本操作

2、JDBC（Java数据库连接）

3、自定义工具类以及properties配置文件的使用

4、JDBC连接池

5、Servlet工作原理与生命周期

6、Servlet请求与响应

---

任务过程

1. 创建数据库，保存用户名和密码

2. 创建登录页面，要求用户输入用户名和密码

3. 创建 servlet接收用户提交的用户名和密码，接收后将数据传递到数据库进行验证

4. 根据验证结果，跳转到不同的结果页面（成功跳转到 success.html、失败
   跳转到 false.html）

---

思路及代码实现

一、 工具包

创建一个utils包，新建类DBUtils，新建配置文件db.properties

properties配置文件

使用ResourceBundle访问本地资源，从里面读取我们需要的值

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT
username=root
password=123456

DBUtils.java

JDBC工具类，封装了操作sql的方法，因此方法都推荐静态static

• 变量定义

	//定义需要的工具类对象（变量定义）
    protected static Connection connection = null;
    protected static PreparedStatement pps = null;//后续都是用预状态通道来实现
    protected static ResultSet rs = null;//结果集
    protected static int count = 0;//受影响的行数
    //登录的用户名和密码
    private static String username;
    private static String password;
    private static String url;
    private static String driverName;
    //Druid连接池
    private static DruidDataSource druidDataSource = new DruidDataSource();

• 加载驱动

	//加载驱动
    static {
    
    
        //Druid
        ResourceBundle bundle = ResourceBundle.getBundle("db");//参数只写属性文件名，不需要写后缀
        //加载属性文件
        driverName = bundle.getString("driver");
        url = bundle.getString("url");
        username = bundle.getString("username");
        password = bundle.getString("password");

        druidDataSource.setUsername(username);
        druidDataSource.setPassword(password);
        druidDataSource.setUrl(url);
        druidDataSource.setDriverClassName(driverName);
    }

• 获得链接

    protected static Connection getConnection() {
    
    
        try {
    
    
            connection = druidDataSource.getConnection();
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return connection;
    }

• 得到预状态通道并绑定参数

	//得到预状态通道
    protected static PreparedStatement getPps(String sql) {
    
    
        try {
    
    
            getConnection();
            pps = connection.prepareStatement(sql);
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return pps;
    }
    
    //绑定参数，给占位符赋值，list中保存的是给占位符所赋的值
    private static void setParams(List list) {
    
    
        try {
    
    
            if (list != null && list.size() > 0) {
    
    //集合中有内容
                for (int i = 0; i < list.size(); i++) {
    
    
                    pps.setObject(i + 1, list.get(i));//赋值，位置从1开始所以为i+1
                }
            }
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
    }

• 增删改

    protected static int update(String sql, List list) {
    
    
        try {
    
    
            getPps(sql);//得到预状态通道
            setParams(list);//绑定参数
            count = pps.executeUpdate();//pps.executeUpdate()执行sql语句，返回受影响的行数
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return count;//返回受影响的行数
    }

• 数据查询

	protected static ResultSet query(String sql, List list) {
    
    
        try {
    
    
            getPps(sql);//得到预状态通道
            setParams(list);//绑定参数
            rs = pps.executeQuery();//pps.executeUpdate()执行sql语句，返回结果集
            return rs;//返回结果集
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return null;
    }

• 关闭资源

    protected static void closeAll() {
    
    
        try {
    
    
            if (rs != null) {
    
    
                rs.close();
            }
            if (pps != null) {
    
    
                pps.close();
            }
            if (connection != null) {
    
    
                connection.close();
            }
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
    }

---

二、 创建数据库

创建数据库demo，建立表user，保存用户名和密码

---

三、 对象

创建一个pojo包，新建类User

User类对应的数据表user，因此类属性名 = 表字段名

User.java

• 定义属性并用setter和getter设置和获取值

    private String username;
    private String userpassword;
    
    public String getUsername() {
    
    
        return username;
    }

    public void setUsername(String username) {
    
    
        this.username = username;
    }

    public String getUserpassword() {
    
    
        return userpassword;
    }

    public void setUserpassword(String userpassword) {
    
    
        this.userpassword = userpassword;
    }

• 定义无参和全参构造方法

    public User() {
    
    
    }

    public User(String username, String userpassword) {
    
    
        this.username = username;
        this.userpassword = userpassword;
    }

• override toString()方法

    @Override
    public String toString() {
    
    
        return "User{" +
                "username='" + username + '\'' +
                ", userpassword='" + userpassword + '\'' +
                '}';
    }

---

四、 创建登录页面

Login.html

要求用户输入用户名和密码

• 浏览器页面主要显示

<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div class="form">
                    <h2>用户登录</h2><br />
                    <form action="test" method="post"><!--使用post发送数据给服务器-->
                        <div>
                            <input id="name" class="inputStyle" name="username" type="text" placeholder="用户名" onblur="validateName()"/>
                        </div>
                        <span id="nameMsg"></span>
                        <div>
                            <input  class="inputStyle" name="userpassword" type="password" placeholder="密码"/>
                        </div>
                        <div>
                            <input class="buttomStyle" type="submit" value="登录" />
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </section>
</body>

• 表单验证

    <script>
        function validateName(){
      
      
            var name = document.getElementById("name").value;
            var msg = document.getElementById("nameMsg");
            var reg = /^[\u4E00-\u9FA5]{2,4}$/;
            var res = reg.test(name);
            if(name == null || name == ""){
      
      
                msg.innerHTML = "用户名不能为空";
                msg.style.color = "red";
                return false;
            }else if(res == false){
      
      
                msg.innerHTML = "用户名格式错误";
                msg.style.color = "red";
                return false;
            }
            return true;
        }
    </script>

• 使用外部样式

    <link rel="stylesheet" href="MyCSS.css">

---

MyCSSss.css

css样式参考文章

• 登录界面总体位置

/**
 * 显示水平居中
 */
section {
    
    
    position: relative;
    overflow: hidden;
    display: flex;   /*垂直居中对齐*/
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    /* linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片 */
    background: linear-gradient(to bottom, #f1f4f9, #dff1ff);
}

.box {
    
    
    position: relative;
}

• 背景颜色

/* 背景颜色 */
.color {
    
    
    /* 绝对定位 */
    position: absolute;
    /* 使用filter(滤镜) 属性，给图像设置高斯模糊*/
    filter: blur(200px);
}

/* :nth-child(n) 选择器匹配父元素中的第 n 个子元素 */
.color:nth-child(1) {
    
    
    top: -350px;
    width: 600px;
    height: 600px;
    background:#FFC0CB;
}

.color:nth-child(2) {
    
    
    bottom: -150px;
    left: 100px;
    width: 500px;
    height: 500px;
    background: #FFFFE0;
}

.color:nth-child(3) {
    
    
    bottom: 50px;
    right: 100px;
    width: 500px;
    height: 500px;
    background:#DDA0DD;
}
.color:nth-child(4) {
    
    
    bottom: 50px;
    right: 100px;
    width: 500px;
    height: 500px;
    background:#FFFFFF;
}

• 登录框样式

/* 登录框样式 */
.container {
    
    
    position: relative;
    width: 400px;
    min-height: 400px;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    justify-content: center;
    align-items: center;
    backdrop-filter: blur(5px);
    box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-right: 1px solid rgba(255, 255, 255, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

• 输入框样式

/* 输入框样式 */
.inputStyle{
    
    
    width: 100%;
    padding: 10px 20px;
    margin-top: 20px;
    background: rgba(255, 255, 255, 0.2);
    outline: none;
    border: none;
    border-radius: 30px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-right: 1px solid rgba(255, 255, 255, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    font-size: 16px;
    letter-spacing: 1px;
    color: #000;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

• 登录按钮样式

/* 登录按钮样式 */
.buttomStyle{
    
    
    width: 100%;
    padding: 10px 20px;
    max-width: 100px;
    margin-top: 30px;
    margin-left: 10px;
    margin-bottom: 20px;
    border-radius: 30px;
    font-size: 16px;
    letter-spacing: 1px;
    background: #fff;
    color: #666;
    font-weight: 600;
    cursor: pointer;
}

---

五、客户端数据发送给服务器

Web.xml

• 在Web.xml文件中添加如下内容

    <servlet>
        <servlet-name>a1</servlet-name><!--名称-->
        <servlet-class>
            servlet.UserServlet  
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>a1</servlet-name><!--映射的名称-->
        <url-pattern>/test</url-pattern><!--<form action="test" method="post">-->
    </servlet-mapping>

---

六、 接收客户端数据

UserServlet .java

创建一个servlet包，新建 UserServlet类，继承HttpServlet，接收客户端输入的用户名和密码

• override doPost方法接受数据

	 @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
    
	    req.setCharacterEncoding("utf-8");
        //取值
        String username = req.getParameter("username");
        System.out.println("用户输入的用户名："+username);
        String userpassword = req.getParameter("userpassword");
        System.out.println("用户输入的密码："+userpassword);
        if(dao.checkLogin(username,userpassword)){
    
    
            System.out.println("登陆成功");
            resp.sendRedirect("/Success.html");
            //req.getRequestDispatcher("/Success.html").forward(req,resp);
        }else{
    
    
            System.out.println("登录失败");
            resp.sendRedirect("/Fail.html");
            //req.getRequestDispatcher("/fail.html").forward(req,resp);
        }
    }

---

七、 数据处理

主要负责数据处理的模块

创建一个dao包，新建 Dao类，继承DBUtils类，使用 JDBC 完成相应数据库操作

Dao.java

    public boolean checkLogin(String username,String password){
    
    
        System.out.println("进入check in");
        String sql = "select* from user where username = ? and userpassword = ?";
        ArrayList param = new ArrayList();
        param.add(username);
        param.add(password);
        ResultSet query = query(sql, param);
        try {
    
    
            if(!query.next()){
    
    
                System.out.println("dao:false");
                return false;
            }else{
    
    
                User user = new User();
                user.setUsername(query.getString("username"));
                user.setUserpassword(query.getString("userpassword"));
                System.out.println("dao:true");
                return true;
            }
        } catch (SQLException throwables) {
    
    
            System.out.println(throwables.getMessage());
            return false;
        }finally {
    
    
            closeAll();
        }
    }

---

八、 登录结果页面

Success.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>登陆成功</title>
    <script type="text/javascript" src="js/jquery-1.11.1.js"></script>
    <script type="text/javascript" src="js/bootstrap.js"></script>
    <link rel="stylesheet" href="css/bootstrap.css" />
    <link rel="stylesheet" href="MyCSS.css">
</head>
<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div>
                    <h2 style="color:#FF69B4">登陆成功</h2>
                </div>
                <div class="progress progress-striped active">
                    <div class="progress-bar progress-bar-info" role="progressbar" aria-valuenow="40"
                         aria-valuemin="0" aria-valuemax="100" style="width: 60%;">
                    </div>
                </div>
            </div>
        </div>
    </section>

</body>
</html>

---

Fail.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>登录失败</title>
    <script type="text/javascript" src="js/jquery-1.11.1.js"></script>
    <script type="text/javascript" src="js/bootstrap.js"></script>
    <link rel="stylesheet" href="css/bootstrap.css" />
    <link rel="stylesheet" href="MyCSS.css">
</head>
<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div>
                    <h2 style="color:#DC143C">用户名or密码错误，登录失败！</h2>
                </div>
                <div class="progress progress-striped active">
                    <div class="progress-bar progress-bar-info" role="progressbar" aria-valuenow="40"
                         aria-valuemin="0" aria-valuemax="100" style="width: 60%;">
                    </div>
                </div>
            </div>
        </div>
    </section>

</body>
</html>

---

完整代码如下

一、 工具包

properties配置文件

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=GMT
username=root
password=123456

DBUtils.java

public class DBUtils {
    
    
    //1.定义需要的工具类对象（变量定义）
    protected static Connection connection = null;
    protected static PreparedStatement pps = null;//后续都是用预状态通道来实现
    protected static ResultSet rs = null;//结果集
    protected static int count = 0;//受影响的行数

    //登录的用户名和密码
    private static String username;
    private static String password;
    private static String url;
    private static String driverName;
    //Druid
    private static DruidDataSource druidDataSource = new DruidDataSource();

    //2.加载驱动
    static {
    
    
        //Druid
        ResourceBundle bundle = ResourceBundle.getBundle("db");//参数只写属性文件名，不需要写后缀
        //加载属性文件
        driverName = bundle.getString("driver");
        url = bundle.getString("url");
        username = bundle.getString("username");
        password = bundle.getString("password");

        druidDataSource.setUsername(username);
        druidDataSource.setPassword(password);
        druidDataSource.setUrl(url);
        druidDataSource.setDriverClassName(driverName);

    }


    //3.获得连接
    protected static Connection getConnection() {
    
    
        try {
    
    
            connection = druidDataSource.getConnection();
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return connection;
    }


    //4.得到预状态通道
    protected static PreparedStatement getPps(String sql) {
    
    
        try {
    
    
            getConnection();//insert into users values(?,?,?,?,)
            pps = connection.prepareStatement(sql);
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return pps;
    }


    //5.绑定参数，给占位符赋值，list中保存的是给占位符所赋的值
    private static void setParams(List list) {
    
    
        try {
    
    
            if (list != null && list.size() > 0) {
    
    //集合中有内容
                for (int i = 0; i < list.size(); i++) {
    
    
                    pps.setObject(i + 1, list.get(i));//赋值，位置从1开始所以为i+1
                }
            }
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
    }


    //6.增删改
    protected static int update(String sql, List list) {
    
    
        try {
    
    
            getPps(sql);//得到预状态通道
            setParams(list);//绑定参数
            count = pps.executeUpdate();//pps.executeUpdate()执行sql语句，返回受影响的行数
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return count;//返回受影响的行数
    }


    //7.查询
    protected static ResultSet query(String sql, List list) {
    
    
        try {
    
    
            getPps(sql);//得到预状态通道
            setParams(list);//绑定参数
            rs = pps.executeQuery();//pps.executeUpdate()执行sql语句，返回结果集
            return rs;//返回结果集
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
        return null;
    }


    //8.关闭资源
    protected static void closeAll() {
    
    
        try {
    
    
            if (rs != null) {
    
    
                rs.close();
            }
            if (pps != null) {
    
    
                pps.close();
            }
            if (connection != null) {
    
    
                connection.close();
            }
        } catch (SQLException e) {
    
    
            e.printStackTrace();
        }
    }


}

---

二、 对象

User.java

public class User {
    
    
    private String username;
    private String userpassword;

    public User() {
    
    
    }

    public User(String username, String userpassword) {
    
    
        this.username = username;
        this.userpassword = userpassword;
    }

    public String getUsername() {
    
    
        return username;
    }

    public void setUsername(String username) {
    
    
        this.username = username;
    }

    public String getUserpassword() {
    
    
        return userpassword;
    }

    public void setUserpassword(String userpassword) {
    
    
        this.userpassword = userpassword;
    }

    @Override
    public String toString() {
    
    
        return "User{" +
                "username='" + username + '\'' +
                ", userpassword='" + userpassword + '\'' +
                '}';
    }
}

---

三、 创建登录页面

Login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户登录</title>
    <link rel="stylesheet" href="MyCSS.css">
    <script>
        function validateName(){
      
      
            var name = document.getElementById("name").value;
            var msg = document.getElementById("nameMsg");
            var reg = /^[\u4E00-\u9FA5]{2,4}$/;
            var res = reg.test(name);
            if(name == null || name == ""){
      
      
                msg.innerHTML = "用户名不能为空";
                msg.style.color = "red";
                return false;
            }else if(res == false){
      
      
                msg.innerHTML = "用户名格式错误";
                msg.style.color = "red";
                return false;
            }
            return true;
        }
    </script>
</head>
<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div class="form">
                    <h2>用户登录</h2><br />
                    <form action="test" method="post">
                        <div>
                            <input id="name" class="inputStyle" name="username" type="text" placeholder="用户名" onblur="validateName()"/>
                        </div>
                        <span id="nameMsg"></span>
                        <div>
                            <input  class="inputStyle" name="userpassword" type="password" placeholder="密码"/>
                        </div>
                        <div>
                            <input class="buttomStyle" type="submit" value="登录" />
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </section>
</body>
</html>

MyCss.css

/**
 * 显示水平居中
 */
section {
    
    
    position: relative;
    overflow: hidden;
    display: flex;   /*垂直居中对齐*/
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    /* linear-gradient() 函数用于创建一个表示两种或多种颜色线性渐变的图片 */
    background: linear-gradient(to bottom, #f1f4f9, #dff1ff);
}

/* 背景颜色 */

.color {
    
    
    /* 绝对定位 */
    position: absolute;
    /* 使用filter(滤镜) 属性，给图像设置高斯模糊*/
    filter: blur(200px);
}

/* :nth-child(n) 选择器匹配父元素中的第 n 个子元素 */

.color:nth-child(1) {
    
    
    top: -350px;
    width: 600px;
    height: 600px;
    background:#FFC0CB;
}

.color:nth-child(2) {
    
    
    bottom: -150px;
    left: 100px;
    width: 500px;
    height: 500px;
    background: #FFFFE0;
}

.color:nth-child(3) {
    
    
    bottom: 50px;
    right: 100px;
    width: 500px;
    height: 500px;
    background:#DDA0DD;
}
.color:nth-child(4) {
    
    
    bottom: 50px;
    right: 100px;
    width: 500px;
    height: 500px;
    background:#FFFFFF;
}
.box {
    
    
    position: relative;
}

/* 登录框样式 */
.container {
    
    
    position: relative;
    width: 400px;
    min-height: 400px;
    background: rgba(255, 255, 255, 0.1);
    display: flex;
    justify-content: center;
    align-items: center;
    backdrop-filter: blur(5px);
    box-shadow: 0 25px 45px rgba(0, 0, 0, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-right: 1px solid rgba(255, 255, 255, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}



/* 输入框样式 */
.inputStyle{
    
    
    width: 100%;
    padding: 10px 20px;
    margin-top: 20px;
    background: rgba(255, 255, 255, 0.2);
    outline: none;
    border: none;
    border-radius: 30px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-right: 1px solid rgba(255, 255, 255, 0.2);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    font-size: 16px;
    letter-spacing: 1px;
    color: #000;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

/* 登录按钮样式 */
.buttomStyle{
    
    
    width: 100%;
    padding: 10px 20px;
    max-width: 100px;
    margin-top: 30px;
    margin-left: 10px;
    margin-bottom: 20px;
    border-radius: 30px;
    font-size: 16px;
    letter-spacing: 1px;
    background: #fff;
    color: #666;
    font-weight: 600;
    cursor: pointer;
}

---

四、客户端数据发送给服务器

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">

    <servlet>
        <servlet-name>a1</servlet-name>
        <servlet-class>
            com.company.project.t010601.servlet.UserServlet
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>a1</servlet-name>
        <url-pattern>/test</url-pattern>
    </servlet-mapping>

</web-app>

---

五、 接收客户端数据

UserServlet .java

public class UserServlet extends HttpServlet {
    
    
    Dao dao = new Dao();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    
    
        //HttpSession session = req.getSession();

        req.setCharacterEncoding("utf-8");
        //取值
        String username = req.getParameter("username");
        System.out.println("用户输入的用户名："+username);
        String userpassword = req.getParameter("userpassword");
        System.out.println("用户输入的密码："+userpassword);
        if(dao.checkLogin(username,userpassword)){
    
    
            System.out.println("登陆成功");
            resp.sendRedirect("/Success.html");
            //req.getRequestDispatcher("/Success.html").forward(req,resp);
        }else{
    
    
            System.out.println("登录失败");
            resp.sendRedirect("/Fail.html");
            //req.getRequestDispatcher("/fail.html").forward(req,resp);
        }
    }
}

---

六、 数据处理

Dao.java

public class Dao extends DBUtil {
    
    
    public boolean checkLogin(String username,String password){
    
    
        System.out.println("进入check in");
        String sql = "select* from user where username = ? and userpassword = ?";
        ArrayList param = new ArrayList();
        param.add(username);
        param.add(password);
        ResultSet query = query(sql, param);
        try {
    
    
            if(!query.next()){
    
    
                System.out.println("dao:false");
                return false;
            }else{
    
    
                User user = new User();
                user.setUsername(query.getString("username"));
                user.setUserpassword(query.getString("userpassword"));
                System.out.println("dao:true");
                return true;
            }
        } catch (SQLException throwables) {
    
    
            System.out.println(throwables.getMessage());
            return false;
        }finally {
    
    
            closeAll();
        }
    }
}

---

七、 登录结果页面

Success.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>登陆成功</title>
    <script type="text/javascript" src="js/jquery-1.11.1.js"></script>
    <script type="text/javascript" src="js/bootstrap.js"></script>
    <link rel="stylesheet" href="css/bootstrap.css" />
    <link rel="stylesheet" href="MyCSS.css">
</head>
<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div>
                    <h2 style="color:#FF69B4">登陆成功</h2>
                </div>
                <div class="progress progress-striped active">
                    <div class="progress-bar progress-bar-info" role="progressbar" aria-valuenow="40"
                         aria-valuemin="0" aria-valuemax="100" style="width: 60%;">
                    </div>
                </div>
            </div>
        </div>
    </section>

</body>
</html>

Fail.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>登录失败</title>
    <script type="text/javascript" src="js/jquery-1.11.1.js"></script>
    <script type="text/javascript" src="js/bootstrap.js"></script>
    <link rel="stylesheet" href="css/bootstrap.css" />
    <link rel="stylesheet" href="MyCSS.css">
</head>
<body>
    <section>
        <div class="box">
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="color"></div>
            <div class="container">
                <div>
                    <h2 style="color:#DC143C">用户名or密码错误，登录失败！</h2>
                </div>
                <div class="progress progress-striped active">
                    <div class="progress-bar progress-bar-info" role="progressbar" aria-valuenow="40"
                         aria-valuemin="0" aria-valuemax="100" style="width: 60%;">
                    </div>
                </div>
            </div>
        </div>
    </section>

</body>
</html>

---