最简单的jsp+servlet的增删改查代码

package ceet.ac.cn.dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;import ceet.ac.cn.model.Admin;public class AdminDao {    public List<Admin> getAllAdmin(){  //查询所有信息        List<Admin> list = new ArrayList<Admin>();  //创建集合        Connection conn = DbHelper.getConnection();        String sql  = "select * from admin";  //SQL查询语句        try {            PreparedStatement pst = conn.prepareStatement(sql);            ResultSet rst = pst.executeQuery();            while (rst.next()) {                Admin admin = new Admin();                admin.setId(rst.getInt("id"));  //得到ID                admin.setUsername(rst.getString("username"));                admin.setUserpwd(rst.getString("userpwd"));                list.add(admin);            }            rst.close();  //关闭            pst.close();  //关闭        } catch (SQLException e) {            e.printStackTrace();  //抛出异常        }        return list;  //返回一个集合    }        public boolean addAdmin(Admin admin){  //添加信息        String sql = "INSERT INTO `admin`(`id`,`username`,`userpwd`) VALUES (?,?,?)";  //添加的SQL语句        Connection conn = DbHelper.getConnection();        try {            PreparedStatement pst = conn.prepareStatement(sql);            pst.setInt(1, admin.getId());            pst.setString(2, admin.getUsername());            pst.setString(3, admin.getUserpwd());            int count = pst.executeUpdate();            pst.close();            return count>0?true:false;  //是否添加的判断        } catch (SQLException e) {            e.printStackTrace();        }        return false;    }        public boolean updateAdmin(Admin admin){  //修改        String sql = "UPDATE `admin` SET `username`=?,`userpwd`=? WHERE `id` = ?";  //修改的SQL语句，根据ID修改        Connection conn = DbHelper.getConnection();        try {            PreparedStatement pst = conn.prepareStatement(sql);            pst.setString(1, admin.getUsername());            pst.setString(2, admin.getUserpwd());            pst.setInt(3, admin.getId());  //根据的ID            int count = pst.executeUpdate();            pst.close();  //关闭            return count>0?true:false;  //是否修改的判断        } catch (SQLException e) {            e.printStackTrace();        }        return false;    }        public boolean deleteAdmin(int id){  //删除        String sql = "delete from admin where id = ?";  //删除的SQL语句，根据ID删除        Connection conn = DbHelper.getConnection();        try {            PreparedStatement pst = conn.prepareStatement(sql);            pst.setInt(1, id);            int count = pst.executeUpdate();            pst.close();            return count>0?true:false;  //是否删除的判断        } catch (SQLException e) {            e.printStackTrace();        }        return false;    }        public Admin selectAdminById(int id){  //根据ID进行查询        Connection conn = DbHelper.getConnection();        String sql  = "select * from admin where id = "+id;        Admin admin = null;        try {            PreparedStatement pst = conn.prepareStatement(sql);            ResultSet rst = pst.executeQuery();            while (rst.next()) {                admin = new Admin();                admin.setId(rst.getInt("id"));                admin.setUsername(rst.getString("username"));                admin.setUserpwd(rst.getString("userpwd"));            }            rst.close();            pst.close();        } catch (SQLException e) {            e.printStackTrace();        }        return admin;  //返回    }

package ceet.ac.cn.dao;import java.sql.Connection;import java.sql.DriverManager;/** * 连接数据库 * @author 画船听雨眠 * */public class DbHelper {    private static String url = "jdbc:mysql://localhost:3306/admin";  //数据库地址    private static String userName = "root";  //数据库用户名    private static String passWord = "359129127";  //数据库密码    private static Connection conn = null;        private DbHelper(){            }        public static Connection getConnection(){        if(null == conn){            try {                Class.forName("com.mysql.jdbc.Driver");                conn = DriverManager.getConnection(url, userName, passWord);            } catch (Exception e) {                e.printStackTrace();            }        }        return conn;    }        public static void main(String[] args) {  //测试数据库是否连通        System.err.println(getConnection());    }}

package ceet.ac.cn.model;import java.io.Serializable;public class Admin implements Serializable{  //数据封装类        private static final long serialVersionUID = 1L;        private int id;    private String username;    private String userpwd;        public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getUserpwd() {        return userpwd;    }    public void setUserpwd(String userpwd) {        this.userpwd = userpwd;    }    }

package ceet.ac.cn.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import ceet.ac.cn.dao.AdminDao;import ceet.ac.cn.model.Admin;public class AddServlet extends HttpServlet{  //添加数据    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        this.doPost(req, resp);    }    protected void doPost(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        String username = req.getParameter("username");        String userpwd = req.getParameter("userpwd");        Admin admin = new Admin();        admin.setUsername(new String(username.getBytes("ISO-8859-1"),"UTF-8"));  //转值，中文需要转换为utf-8        admin.setUserpwd(new String(userpwd.getBytes("ISO-8859-1"),"UTF-8"));        AdminDao dao = new AdminDao();        dao.addAdmin(admin);        req.getRequestDispatcher("ShowServlet").forward(req, resp);    }    }

package ceet.ac.cn.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import ceet.ac.cn.dao.AdminDao;public class DeleteServlet extends HttpServlet{  //删除数据    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        this.doPost(req, resp);    }    protected void doPost(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        String idStr = req.getParameter("id");  //删除数据的ID，根据ID删除        if(idStr != null && !idStr.equals("")){            int id = Integer.valueOf(idStr);            AdminDao dao = new AdminDao();            dao.deleteAdmin(id);        }        req.getRequestDispatcher("ShowServlet").forward(req, resp);    }        }

package ceet.ac.cn.servlet;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import ceet.ac.cn.dao.AdminDao;import ceet.ac.cn.model.Admin;public class ShowServlet  extends HttpServlet{  //显示全部数据    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        this.doPost(req, resp);    }    protected void doPost(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {        AdminDao dao = new AdminDao();        List<Admin> list = dao.getAllAdmin();        req.setAttribute("list", list);        req.getRequestDispatcher("index.jsp").forward(req, resp);    }    }

package ceet.ac.cn.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import ceet.ac.cn.dao.AdminDao;import ceet.ac.cn.model.Admin;public class UpdateServlet extends HttpServlet{  //修改    private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {  //查询到选中ID的值所对应的数据        String idStr = req.getParameter("id");        if(idStr != null && !idStr.equals("")){            int id = Integer.valueOf(idStr);            AdminDao dao = new AdminDao();            Admin admin = dao.selectAdminById(id);            req.setAttribute("admin", admin);        }        req.getRequestDispatcher("update.jsp").forward(req, resp);            }    protected void doPost(HttpServletRequest req, HttpServletResponse resp)            throws ServletException, IOException {  //根据此ID对数据的值进行修改        String username = req.getParameter("username");        String userpwd = req.getParameter("userpwd");        String idStr = req.getParameter("id");        Admin admin = new Admin();        admin.setId(Integer.valueOf(idStr));        admin.setUsername(new String(username.getBytes("ISO-8859-1"),"UTF-8"));        admin.setUserpwd(new String(userpwd.getBytes("ISO-8859-1"),"UTF-8"));        AdminDao dao = new AdminDao();        dao.updateAdmin(admin);        req.getRequestDispatcher("ShowServlet").forward(req, resp);    }        }

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>        <title>添加</title>    <link rel="stylesheet" href="css/index.css" type="text/css" />  </head>  <body>  <form action="AddServlet" method="post">    <table border="1" class="t1">        <tr>            <td colspan="2"><h1>添加管理员</h1></td>        </tr>        <tr>            <td>管理员帐号:</td>            <td><input  type="text" name="username"/></td>        </tr>        <tr>            <td>管理员密码:</td>            <td><input  type="password" name="userpwd"/></td>        </tr>        <tr>            <td colspan="2">                <input  type="submit" value="提交"/>                <input  type="reset" value="清空"/>            </td>        </tr>    </table>   </form>  </body></html>

<%@ page language="java" contentType="text/html; charset=utf-8"    pageEncoding="utf-8"%><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><!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>显示</title>    <style type="text/css">            table {                border: 1px solid pink;                margin: 0 auto;            }                        td{                width: 150px;                border: 1px solid pink;                text-align: center;            }    </style></head><body>    <table>        <tr>            <td>编号</td>            <td>帐号</td>            <td>密码</td>            <td>操作</td>        </tr>        <c:forEach items="${list}" var="item">            <tr>                <td>${item.id }</td>                <td>${item.username }</td>                <td>${item.userpwd }</td>                <td><a href="DeleteServlet?id=${item.id }">删除</a>|<a href="UpdateServlet?id=${item.id }">修改</a></td>            </tr>        </c:forEach>        <tr>            <td colspan="6" style="text-align: left;"><a href="add.jsp">添加管理员</a></td>        </tr>    </table></body></html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>        <title>修改</title>    <link rel="stylesheet" href="css/index.css" type="text/css" />  </head>    <body>    <form action="UpdateServlet" method="post">    <table border="1" class="t1">        <tr>            <td colspan="2"><h1>修改管理员信息</h1></td>        </tr>        <tr>            <td>编号:</td>            <td><input  type="text" name="id" value="${admin.id}" readonly="readonly"/></td>        </tr>                <tr>            <td>管理员帐号:</td>            <td><input  type="text" name="username" value="${admin.username}"/></td>        </tr>        <tr>            <td>管理员密码:</td>            <td><input  type="text" name="userpwd" value="${admin.userpwd}"/></td>        </tr>        <tr>            <td colspan="2">                <input  type="submit" value="提交"/>                <input  type="button" value="返回" onclick="history.go(-1)"/>            </td>        </tr>    </table>   </form>  </body></html>

@CHARSET "UTF-8";        table.t1 {            margin-top:10px;            margin-left:20px;            margin-right:20px;            margin-bottom:5px;            #background-color: #FFF;            #background:#EEF4F9;            #border: none;            border: 1;            #color:#003755;            border-collapse:collapse;            font: 14px  "宋体";            text-align: center;        }        table.t1 th{                background:#7CB8E2;                color:#fff;                padding:6px 4px;                text-align:center;        }        table.t1 td{                background:#C7DDEE none repeat-x scroll center left;                color:#000;                padding:4px 2px;        }        table.t1 a{                text-decoration:none;                height:1em;        }        table.t1 a:link, table.t1  a:visited{                color:#3366CC;        }        table.t1  a:hover{                color:#B50000;                text-decoration:underline;        }


                                             
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