Web实现数据库链接的登录注册修改密码功能

/**
 * Copyright (C), 2017-2017
 * FileName: User
 * Author:   ichimoku
 * Date:     2017/12/5 14:31
 * version:  7.9.0
 * <Author>          <Date>          <version>
 * 作者姓名          修改时间         版本号
 */
public class User {

    //登陆查询  -----  括号内接收从网页传来的用户输入的参数
    public static Boolean CheckUser(String username,String password) {
        int count = 0;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println("加载驱动失败");
        }
        // 2.建立连接
        try {
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/数据库名", "用户名", "密码");
            /*System.out.println("建立连接成功！");*/

            String sql = "SELECT id FROM account WHERE name=? AND password=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,username);
            ps.setString(2,password);
            rs=ps.executeQuery();

            while (rs.next()){
                count++;
            }
            
        } catch (SQLException e) {
            System.out.println("建立连接失败");
        } finally {
            // 3.关闭连接
            try {
                if (null != conn) {
                    conn.close();
                }
                if (null != ps) {
                    ps.close();
                }
                /*System.out.println("关闭连接成功!");*/
            } catch (SQLException e) {
                System.out.println("程序错误");
            }
        }
        return count>0 ? true:false;
    }


    //新增用户   -----  括号内接收从网页传来的用户输入的参数
    public static void  AddUser(String username,String password) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println("加载驱动失败");
        }
        // 2.建立连接
        try {
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/数据库名", "用户名", "密码");
            /*System.out.println("建立连接成功！");*/

            String sql = "INSERT INTO account SET (name,password) VALUE (?,?)";
            ps=conn.prepareStatement(sql);
            ps.setString(1,username);
            ps.setString(2,password);
            rs=ps.executeQuery();
        } catch (SQLException e) {
            System.out.println("建立连接失败");
        } finally {
            // 3.关闭连接
            try {
                if (null != conn) {
                    conn.close();
                }
                if (null != ps) {
                    ps.close();
                }
                System.out.println("关闭连接成功!！！");
            } catch (SQLException e) {
                System.out.println("程序错误");
            }
        }
    }


    //修改密码  ---  括号内接收从网页传来的用户输入的参数
    public static void  UpdateUser(String newpassword,String username,String password) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        // 1.加载驱动
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println("加载驱动失败");
        }
        // 2.建立连接
        try {
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/数据库名", "用户名", "密码");
            /*System.out.println("建立连接成功！");*/

            String sql = "UPDATE account SET password=? WHERE name=? AND password=?";
            ps=conn.prepareStatement(sql);
            ps.setString(1,newpassword);
            ps.setString(2,username);
            ps.setString(3,password);
            rs=ps.executeQuery();

        } catch (SQLException e) {
            System.out.println("建立连接失败");
        } finally {
            // 3.关闭连接
            try {
                if (null != conn) {
                    conn.close();
                }
                if (null != ps) {
                    ps.close();
                }
                System.out.println("关闭连接成功!");
            } catch (SQLException e) {
                System.out.println("程序错误");
            }
        }
    }
}

/**
 * Copyright (C), 2017-2017
 * FileName: Check
 * Author:   ichimoku
 * Date:     2017/12/5 14:40
 * version:  7.9.0
 * <Author>          <Date>          <version>
 * 作者姓名          修改时间         版本号
 */

@WebServlet(name="CheckUser",urlPatterns="/servlet/CheckUser")
public class CheckUser extends HttpServlet{
    private static final long serialVersionUID = 1L;

    public CheckUser(){
        super();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //从网页获取输入的用户名和密码
        String username = new String(req.getParameter("username").getBytes("iso-8859-1"), "utf-8");
        String password = req.getParameter("password");

        //在控制台打印从网页获取到的用户名
        System.out.println(username);

        //判断用户名和密码是否为空
        if (username!=null && password!=null){
            boolean flag= User.CheckUser(username,password);
            //通过flag返回值 为true就会执行if，false就会执行else
            if (flag){
                req.getRequestDispatcher("/pages/user/login_success.html").forward(req, resp);
            }else{
                //req.getRequestDispatcher("/pages/user//Welcome.jsp").forward(req, resp);
            }
        }else{
            System.out.println("用户的输入为空");
        }
    }
}

/**
 * Copyright (C), 2017-2017
 * FileName: Add
 * Author:   ichimoku
 * Date:     2017/12/5 16:01
 * version:  7.9.0
 * <Author>          <Date>          <version>
 * 作者姓名          修改时间         版本号
 */
@WebServlet(name="AddUser",urlPatterns="/servlet/AddUser")
public class AddUser extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public AddUser(){
        super();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //从网页获取输入的用户名和密码
        String username = new String(req.getParameter("username").getBytes("iso-8859-1"), "utf-8");
        String password = req.getParameter("password");

        //在控制台打印从网页获取到的用户名
        System.out.println(username);

        //判断用户名和密码是否为空
        if (username!=null && password!=null){
            boolean flag=User.CheckUser(username,password);
            //通过flag返回值 为true就会执行if，false就会执行else，因为我们要新增用户，如果返回ture就说明
            //这个账号已经有人使用，所以我们要提示注册失败，如果返回false,说明数据库里没有这个账号，可以注册
            //在else里运行AddUser的方法，成功数据库在数据库里新增注册数据！
            if (flag){
                //req.getRequestDispatcher("/pages/user//Welcome.jsp").forward(req, resp);
            }else{
                //req.getRequestDispatcher("/pages/user//Welcome.jsp").forward(req, resp);
                User.AddUser(username,password);
                req.getRequestDispatcher("/pages/user/login_success.html").forward(req, resp);
            }
        }else{
            System.out.println("用户的输入为空");
        }
    }
}

/**
 * Copyright (C), 2017-2017
 * FileName: Update
 * Author:   ichimoku
 * Date:     2017/12/5 16:05
 * version:  7.9.0
 * <Author>          <Date>          <version>
 * 作者姓名          修改时间         版本号
 */

@WebServlet(name="UpdateUser",urlPatterns="/servlet/UpdateUser")
public class UpdateUser extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public UpdateUser(){
        super();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //从网页获取输入的用户名和密码
        String username = new String(req.getParameter("username").getBytes("iso-8859-1"), "utf-8");
        String password = req.getParameter("password");
        String newpassword = req.getParameter("newpassword");

        //在控制台打印从网页获取到的用户名
        System.out.println(username);

        //判断用户名和密码是否为空
        if (username!=null && password!=null){
            boolean flag=User.CheckUser(username,password);
            //通过flag返回值 为true就会执行if，false就会执行else，因为我们要修改密码，所以当返回true，说明用户输入的账号密码
            // 和数据库匹配成功！所以我们在if下面执行UpdateUser方法，修改数据库数值！
            if (flag){
                User.UpdateUser(newpassword,username,password);
                req.getRequestDispatcher("/pages/user/login_success.html").forward(req, resp);
            }else{
                //req.getRequestDispatcher("/pages/user//Welcome.jsp").forward(req, resp);
            }
        }else {
            System.out.println("用户的输入为空");
        }
    }
}