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Javaweb实现简易记事簿 jdbc实现Java连接数据库

时间：2024-06-18 14:34:56浏览次数：23  
标签：username jdbc Java request 记事簿 stmt SQLException null public

//注册- [ ] 获取register的数据，从表单传过来

将（账户，密码，用户名）上面的数据写入数据库中，用jdbc（插入）加载数据库驱动，连接数据库，发送SQL

加载数据库有可能失败保险起见抛一个异常

返回判断，如果注册成功则提醒用户注册成功，并且跳转到登录页面进行登录。如果注册失败则提醒用户注册失败，并返回到注册页面。

最后关闭数据库

等等

//登录- [ ] 去数据库里面的user表中查询看能不能找到对应相应的用户，如果找到能不能匹配他相应的密码看一不一样。

接收来自login输入的值：用户名和密码。将用户名与数据库的usercode进行查找（加载数据库驱动，然后连接数据库，然后发送SQL）

将密码取出来与接收到的密码进行匹配，如果两个密码一致，则证明登录成功。如果不一致则说明密码输入错误。

如果找不到则说明用户名错误

然后加入语句来提示。
//相关代码
import jakarta.servlet.;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
import java.time.LocalDate;

//主界面
@WebServlet("/Main")
public class Main implements Servlet{
private ServletConfig config;

@Override
public void init(ServletConfig config) throws ServletException{
    this.config = config;
}

@Override
public ServletConfig getServletConfig(){
    return config;
}

@Override
public void service(ServletRequest request, ServletResponse response)
        throws ServletException, IOException{
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;UTF-8");

    Connection conn = null;
    Statement stmt = null;
    ResultSet rsId = null, rsEvent = null;

    try{
        DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
        stmt = conn.createStatement();

        HttpSession session = ((HttpServletRequest)request).getSession(false);

        if(session == null || session.getAttribute("username") == null){
            RequestDispatcher dispatcher = request.getRequestDispatcher("/LogOutMain.html");
            dispatcher.forward(request, response);
        }
        else{
            PrintWriter out = response.getWriter();
            String username = (String)session.getAttribute("username");

            boolean hasEvent = false;
            rsId = stmt.executeQuery("select userid from users where username = '" + username + "'");
            rsId.next();
            int userid = rsId.getInt(1);
            rsEvent = stmt.executeQuery("select date from e" + userid + " order by date");
            if(rsEvent.next()){
                Date eventDate = rsEvent.getDate(1);
                Date now = Date.valueOf(LocalDate.now());
                if(now.equals(eventDate)) hasEvent = true;
            }

            out.print("""
                <html lang="zh-CN">
                    <head>
                        <meta charset="utf-8"/>
                        <title>日历</title>
                        <style>
                            .right-align{
                              text-align: right;
                            }
                          </style>
                    </head>
                    <body>
                        <div class="right-align">
                            <strong>你好 <a href="/crm/UserInfo">""" + username + """
                        </a><strong>
                        </div>
                        <br><br><br><br><br><br><br><br>
                        <script type="text/javascript">
                            var date = new Date();
                            var year = date.getFullYear();
                            var month = date.getMonth();
                            var day = date.getDate();
                            var dayOfWeek = date.getDay();
                            var arr = ["日", "一", "二", "三", "四", "五", "六"];
                            document.write("<h1><center>" + year + "年" + (month + 1) + "月" + day + "日</center></h1><br><center><h2>星期" + arr[dayOfWeek] + "</h2></center>");
                        </script>
                                    
                        <br><br><br><br><br><br><br><br>
                        <center>
                            <a href="/crm/LogOut">退出登录</a>&nbsp;&nbsp;&nbsp;
                            <a href="/crm/Close">账号注销</a>&nbsp;&nbsp;&nbsp;
                            <a href="/crm/Events">查看事件""" + (hasEvent ? "（今日有待办）" : "<br>") + """
                        </a>
                        </center>
                    </body>
                </html>
                """);
        }
    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsId != null)
            try{
                rsId.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsEvent != null)
            try{
                rsEvent.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "Main";
}

@Override
public void destroy(){

}

}
{
private ServletConfig config;

@Override
public void init(ServletConfig config) throws ServletException{
    this.config = config;
}

@Override
public ServletConfig getServletConfig(){
    return config;
}

@Override
public void service(ServletRequest request, ServletResponse response)
        throws ServletException, IOException{
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;UTF-8");

    Connection conn = null;
    Statement stmt = null;
    ResultSet rsId = null, rsEvent = null;

    try{
        DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
        stmt = conn.createStatement();

        HttpSession session = ((HttpServletRequest)request).getSession(false);

        String year = request.getParameter("year");
        String month = request.getParameter("month");
        String date = request.getParameter("date");
        String event = request.getParameter("event");

        String username = (String)session.getAttribute("username");
        rsId = stmt.executeQuery("select userid from users where username = '" + username + "'");
        rsId.next();
        int userid = rsId.getInt(1);

        if(year == null || year.isEmpty() || month == null || month.isEmpty() || date == null || date.isEmpty()
            || event == null || event.isEmpty()){
            RequestDispatcher dispatcher = request.getRequestDispatcher("/UserAct/NullEvent.html");
            dispatcher.forward(request, response);
        }
        else{
            rsEvent = stmt.executeQuery("select * from e" + userid + " where date = '" + year + "-" + month + "-" + date + "' and info = '" + event + "'");
            if(rsEvent.next()){
                RequestDispatcher dispatcher = request.getRequestDispatcher("/UserAct/SameEvent.html");
                dispatcher.forward(request, response);
            }
            else{
                stmt.executeUpdate("insert into e" + userid + " values('" + year + "-" + month + "-" + date + "', '" + event + "')");
                stmt.executeUpdate("update users set eventCnt = eventCnt + 1 where username = '" + username + "'");
            }

            ((HttpServletResponse)response).sendRedirect("/crm/Events");
        }

    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsId != null)
            try{
                rsId.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsEvent != null)
            try{
                rsEvent.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "UserAct.AddEvent";
}

@Override
public void destroy(){

}

}
package UserAct;

import jakarta.servlet.;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.;
import java.io.;
import java.sql.;

//登出
try{
DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
stmt = conn.createStatement();

        rs = stmt.executeQuery("select userid from users where username = '" + username + "'");
        rs.next();
        int userid = rs.getInt(1);

        stmt.executeUpdate("delete from users where username = '" + username + "'");
        stmt.execute("drop table e" + userid);

        session.invalidate();
        PrintWriter out = response.getWriter();
        out.print("""               
                <html>
                    <head>
                        <meta charset="utf-8"/>
                        <title>注销成功</title>
                    </head>
                    <body>
                        <h1>账号已注销！</h1>
                        <a href="/crm/Main">回到主页面</a>
                    </body>
                </html>
        """);

    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rs != null)
            try{
                rs.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "UserAct.Close";
}

@Override
public void destroy(){

}

package UserAct;

import jakarta.servlet.;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.;
import java.io.;
import java.sql.;

//登出
@WebServlet("/UserAct.DeleteEvent")
public class DeleteEvent implements Servlet{
private ServletConfig config;

@Override
public void init(ServletConfig config) throws ServletException{
    this.config = config;
}

@Override
public ServletConfig getServletConfig(){
    return config;
}

@Override
public void service(ServletRequest request, ServletResponse response)
        throws ServletException, IOException{
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;UTF-8");

    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null, rsId = null, rsEvent = null;;

    try{
        DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
        stmt = conn.createStatement();

        HttpSession session = ((HttpServletRequest)request).getSession(false);
        String username = (String)session.getAttribute("username");

        String req = request.getParameter("delete");
        int line = 0;
        if(req == null || req.isEmpty()){
            RequestDispatcher dispatcher = request.getRequestDispatcher("/UserAct/NullDelete.html");
            dispatcher.forward(request, response);
        }
        else{
            line = Integer.parseInt(req);

            rs = stmt.executeQuery("select eventCnt from users where username = '" + username + "'");
            rs.next();
            int eventCnt = rs.getInt(1);

            if(line > eventCnt){
                RequestDispatcher dispatcher = request.getRequestDispatcher("/UserAct/SegmentationFault.html");
                dispatcher.forward(request, response);
            }
            else{
                rsId = stmt.executeQuery("select userid from users where username = '" + username + "'");
                rsId.next();
                int userid = rsId.getInt(1);

                rsEvent = stmt.executeQuery("select * from e" + userid + " order by date");
                while(line -- > 0) rsEvent.next();
                String event = rsEvent.getString("info");
                stmt.executeUpdate("delete from e" + userid + " where info = '" + event + "'");
                stmt.executeUpdate("update users set eventCnt = eventCnt - 1 where username = '" + username + "'");

                ((HttpServletResponse)response).sendRedirect("/crm/Events");
            }
        }

    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rs != null)
            try{
                rs.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsEvent != null)
            try{
                rsEvent.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsId != null)
            try{
                rsId.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "UserAct.DeleteEvent";
}

@Override
public void destroy(){

}

}
package UserAct;

import jakarta.servlet.;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.;
import java.io.;
import java.sql.;
import java.time.LocalDate;

//登出
@WebServlet("/UserAct.Events")
public class Events implements Servlet{
private ServletConfig config;

@Override
public void init(ServletConfig config) throws ServletException{
    this.config = config;
}

@Override
public ServletConfig getServletConfig(){
    return config;
}

@Override
public void service(ServletRequest request, ServletResponse response)
        throws ServletException, IOException{
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;UTF-8");

    Connection conn = null;
    Statement stmt = null;
    ResultSet rsId = null, rsEvent = null;

    try{
        DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
        stmt = conn.createStatement();

        HttpSession session = ((HttpServletRequest)request).getSession(false);
        String username = (String)session.getAttribute("username");

        rsId = stmt.executeQuery("select userid from users where username = '" + username + "'");
        rsId.next();
        int userid = rsId.getInt(1);
        rsEvent = stmt.executeQuery("select * from e" + userid + " order by date");

        int eventCnt = 0;
        String result = "";
        Date now = Date.valueOf(LocalDate.now());
        Date lastDate = null;
        while(rsEvent.next()){
            Date eventDate = rsEvent.getDate("date");
            if(eventDate.compareTo(now) < 0){
                int cnt = stmt.executeUpdate("delete from e" + userid + " where date = '" + eventDate + "'");
                stmt.executeUpdate("update users set eventCnt = eventCnt - " + cnt + " where username = '" + username + "'");
            }
            else if(!eventDate.equals(lastDate)){
                lastDate = eventDate;
                if(eventDate.equals(now))
                    result += "<h2>今日</h2>";
                else result += "<h2>" + eventDate + "</h2>";
            }

            eventCnt ++;
            result += "<strong>" + eventCnt + "</strong>&nbsp;&nbsp;&nbsp;" + rsEvent.getString("info") + "<br>";
        }

        PrintWriter out = response.getWriter();
        out.print("""
                <html>
                    <head>
                        <meta charset="utf-8"/>
                        <title>事件簿</title>
                    </head>
                    <body>
                        <form action="DeleteEvent" method="post">
                            <label for="username">删除事件（输入事件编号）</label> <br>
                            <input type="text" name="delete"/> <br><br>
                            <input type="submit" value="删除"/> *过期事件会自动删除，添加过期事件是无效添加<hr>
                        </form>
                        <form action="AddEvent" method="post">
                            <label for="username">添加事件</label> <br>
                            
                            <label for="username">日期</label>&nbsp;&nbsp;
                            <input type="text" name="year"/>年&nbsp;
                            <input type="text" name="month"/>月&nbsp;
                            <input type="text" name="date"/>日 <br><br>
                            
                            <textarea rows="10" cols="40" name="event" placeholder="在此输入具体内容"></textarea> <br><br>
                            
                            <input type="submit" value="添加"/><hr>
                        </form>
                        <a href="Main">返回主界面</a> <br><br>
                        <h1>事件簿</h1>""" + result + """
                    </body>
                </html>
        """);

    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsEvent != null)
            try{
                rsEvent.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rsId != null)
            try{
                rsId.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "UserAct.Events";
}

@Override
public void destroy(){

}

}
package UserAct;

import jakarta.servlet.;
import jakarta.servlet.annotation.WebServlet;
import java.io.;
import jakarta.servlet.http.;
import java.sql.;

//用户信息
@WebServlet("/UserAct.UserInfo")
public class UserInfo implements Servlet{
private ServletConfig config;

@Override
public void init(ServletConfig config) throws ServletException{
    this.config = config;
}

@Override
public ServletConfig getServletConfig(){
    return config;
}

@Override
public void service(ServletRequest request, ServletResponse response)
        throws ServletException, IOException{
    request.setCharacterEncoding("UTF-8");
    response.setContentType("text/html;UTF-8");

    HttpSession session = ((HttpServletRequest)request).getSession(false);
    String username = (String)session.getAttribute("username");
    int userid = 0, eventCnt = 0;

    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;

    try{
        DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver());
        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/HTTPServer", "root", "lcy333668");
        stmt = conn.createStatement();

        PrintWriter out = response.getWriter();

        rs = stmt.executeQuery("select userid, eventCnt from users where username = '" + username + "'");
        rs.next();
        userid = rs.getInt(1);
        eventCnt = rs.getInt(2);

        out.print("""
                <html lang="zh-CN">
                    <head>
                        <meta charset="utf-8"/>
                        <title>用户信息</title>
                    </head>
                    <body>
                        <h1>""" + username + """
                        </h1> <hr>
                        <h2>用户id</h2>""" + userid + """
                        <br>
                        <h2>用户事件数量</h2>""" + eventCnt + """
                        <br><br>
                        <a href="#" onclick="window.history.back(); return false">返回</a>
                    </body>
                </html>
        """);

    }catch(SQLException e){
        e.printStackTrace();
    }finally{
        if(conn != null)
            try{
                conn.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(stmt != null)
            try{
                stmt.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
        if(rs != null)
            try{
                rs.close();
            }catch(SQLException e){
                e.printStackTrace();
            }
    }
}

@Override
public String getServletInfo(){
    return "UserAct.UserInfo";
}

@Override
public void destroy(){

}

}

标签：username,jdbc,Java,request,记事簿,stmt,SQLException,null,public
From： https://www.cnblogs.com/qgmz/p/18254267

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