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
a5f8
, 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;
}