最简单的jsp+servlet的增删改查代码

时间：2022-12-19 18:11:45
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;

        }

最简单的jsp+servlet的增删改查代码。写的很清楚，就这样了。

实现原理： 
每行数据后面加一个编辑和删除按钮，按钮提交到后台并且带有此行数据的主要参数。 
点击编辑按钮，通过servlet操作jsp将此行的每一列替换为一个文本框并把已有的值带进去，后面一个提交按钮通过submit提交数据并将文本框重新变为表格的单元格。 
新增，就像编辑一样，添加一行，全部是文本框。。。

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