jsp+servlet+jdbc实现对数据库简单的增删改查

入职以来（来京六整月），一直在学习JavaWeb的知识，分享下最近几个月（断断续续）用jsp+servlet+jdbc实现的一个demo，这个demo借鉴了网上很多前辈的经验，希望自己能够不断进步。

效果图如下：

1、首先介绍下开发所需要工具，以及相应的开发环境：
eclipse+tomcat+mysql+jdk；

2、创建数据库userdemo，然后创建userdemo及userinfo表

3、接下来在eclipse中搭建web工程，相应目录如下图所示，并导入相应的包（需要mysql连接jdbc的jar包，以及jstl的jar包）

4、对应jsp页面的代码
（1）登陆界面logon.jsp：

<%@ page import="java.sql.*" language="java" import="java.util.*" pageEncoding="utf-8" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>   
<!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=ISO-8859-1">
<title>用户登陆界面</title>

<style type="text/css">
body {
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-size: 100% 100%;
    color: #000;
    font-family: "微软雅黑";
    font-size: 1.6em;
}
#div1 {
    text-align: center;
    width: 200px;
    height: 200px;
}
#span {
    font-size: 9px;
}
</style>

<script>
function myFunction(){
	var x = document.getElementById("psw").value;
	if(x==""||isNaN(x)){
		 alert("密码不能为空!");
		 return;
	}
	var y = document.getElementById("usn").value;
	if(y==""){
		alert("用户名不能为空!");
		return;
	}
	document.getElementById("form1").submit();
}
</script>
</head>

<body>

<div id="div1">
	<form id="form1" action="logon" method="post">
		<p>
			<label for="username">用户名</label>
			<input id="usn" type="text" name="username">
		</p>
		<p>
			<label for="password">密码</label>
			<input id="psw" type="password" name="password">
		</p>
		<input type="button" onclick="myFunction()" value="登陆" >
	</form>
</div>

</body>
</html>

（2）主界面home.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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=ISO-8859-1">
	<title>人员信息</title>
</head>
	<!-- frame对应的导航框架 -->
	<frameset rows="93%,*" >	
		<frameset cols="20%, *" noresize="noresize" >
			<frame src="left.jsp" frameborder="1" name="leftFrame" />
			<frame src="userlistright" frameborder="1" name="rightFrame" />
		</frameset>
	<frame src="footer.jsp" frameborder="1" name="footerFrame"/>
	</frameset>
</html>

（3）左侧部分left.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>

<!-- head部分 -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>人员信息</title>
	<style type="text/css">
		a:link,a:visited {
			text-decoration: none;  /*超链接无下划线*/
		}
		a:hover{
			text-decoration:underline;  /*鼠标放上去有下划线*/
		}
		li{
			list-style: none; /*去除li前面的小黑点*/
		}
	</style>
</head>
<!--js:对应跳转部分 -->
<script type="text/javascript">
	function add(){
		window.parent.rightFrame.location.href='addright.jsp'
	}
	function userList(){
		window.parent.rightFrame.location.href='userlistright' 
	}
</script>
<body>
	<div> 
		<h3 style="margin-center">人员信息</h3>
		<ul>
			<li>
				<a href="#" onclick="add()">新增</a>
			</li>
			<li>
				<a href="#" onclick="userList()">人员列表</a> 
			</li>
		</ul>
	</div>
</body>
</html>

(4)右侧部分(人员列表)userlistright

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ page import="dao.UserInfoDaoMrg" %>
<%@ page import="entity.UserInfo" %>
<%@ page import="java.util.*" %>
<%@ page import="bean.Page" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- head部分 -->
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	<title>人员列表</title>	
	<style type="text/css">
		a:link,a:visited {
			text-decoration: none;  /*超链接无下划线*/
		}
		a:hover{
			text-decoration:underline;  /*鼠标放上去有下划线*/
		}
		td{ 
			text-align:center;
		}		
				
	</style>
</head>

<!--js:对应跳转部分 -->
<script>
	function refreshList(){
		window.parent.rightFrame.location.href='userlistright' //servlet
	}
	
	function add(){
		window.parent.rightFrame.location.href='addright.jsp' //
	}
	
	function delFun(){
		window.parent.rightFrame.location.href='userlistright' //
	}	
	
	function editFun(){
		window.parent.rightFrame.location.href='addright.jsp' //
	}	
	
</script>
<body>
	<div style="margin-top:10px; margin-bottom:10px;"> 
		<button id="refreshbutton" style="width:80px;height:40px;margin-left:10px" type="button" onclick="refreshList()">刷新界面</button>
		<button id="addbutton" style="width:80px;height:40px;" type="button" onclick="add()">新增</button>
	</div>
	
	<div>
		<table id="user_list"  border="1"  cellspacing="0" cellpadding="0" style="border:1px solid gray; border-radius:4px">
			<thead>
				<tr>
			     	<th style="width:100px;text-align:center">工号</th>
					<th style="width:80px;text-align:center">姓名</th>
					<th style="width:120px;text-align:center">技术水平</th>
					<th style="width:120px;text-align:center">所在部门</th>
					<th style="width:160px;text-align:center">角色</th>
					<th style="width:180px;text-align:center">操作</th>
				</tr>		
			</thead>
		
			<tbody>
				<%
					List<UserInfo> list = (List<UserInfo>)request.getAttribute("list");					
					for(UserInfo user : list){
				%>
				<tr>
				    <td style="width:100px;text-align:center"><%=user.getJobNumber()%></td>
					<td style="width:80px;text-align:center"><%=user.getName()%></td>
					<td style="width:120px;text-align:center"><%=user.getLevel()%></td>
					<td style="width:120px;text-align:center"><%=user.getDepartment()%></td>
					<td style="width:160px;text-align:center"><%=user.getRole()%></td>
					<td><a href="deleteUserServlet?id=<%=user.getId()%>" onclick="return confirm('是否确认删除<%=user.getName()%>信息?')">删除</a>  
					<a href="selectUserServlet?id=<%=user.getId()%>">修改</a></td>
				</tr>	
				<%
					}
				%>
				
			</tbody>		
		</table>
	</div>
	
	<div style="width:800px">	    
		<c:choose>
			<c:when test="${page.pageNum<=1}">
				<a href="userlistright?pageNum = 1 ">前一页</a>
			</c:when>
			<c:otherwise>
				<a href="userlistright?pageNum=${page.pageNum-1}">前一页</a>
			</c:otherwise>
		</c:choose>
	
    	<c:forEach var="i" begin="1" end="${page.pageTotal}" step="1">
			<a href="userlistright?pageNum=${i}">${i}</a>
		</c:forEach>
		
		<c:choose>
			<c:when test="${page.pageNum >= page.pageTotal}%>">
				<a href="userlistright?pageNum=${page.pageTotal}">后一页</a>
			</c:when>
			<c:otherwise>
				<a href="userlistright?pageNum=${page.pageNum + 1}">后一页</a>
			</c:otherwise>
		</c:choose>		
		<span style="margin-left:10px">一共${page.pageTotal}页</span>
	</div>
</body>
</html>

(5)footer.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<div class="footer">
	<div class="container_1"> 
		<p>
			Designed by <a href="http://www.baidu.com" target="_blank">百度</a>		
		</p>
	</div>
</div>

(6)增加人员界面addright.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!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>新增</title>
</head>
<script>
	function confirmFun(){		
		var x1 = document.getElementById("name").value;
		var x2 = document.getElementById("jobNumber").value;
		var x3 = document.getElementById("level").value;
		var x4 = document.getElementById("department").value;
		var x5 = document.getElementById("role").value;
		if(x1==""||isNaN(x1)||x2==""||isNaN(x2)||x3==""||isNaN(x3)||x4==""||isNaN(x4)
				||x5==""||isNaN(x5)){
			 alert("添加信息不完整");
			 return;
		}		
		document.getElementById("form").submit();
	}
	
	function resetFun(){
		var spans = document.getElementsByTagName("input");
		for(var j=0;j<spans.length;j++){  
			var span = spans[j]; // input标签的数组
			document.getElementById(span.id).value ="";//
			console.info(span.id);
		}
	}
</script>

<body>
 <h3>新增页面</h3>
    <form  id="form" action="addright" method="post">    
             工号：<input id="jobNumber" name="jobNumber"><br>
	    姓名：<input id="name" name="name"><br>
	    技术水平：<input id="level" name="level"><br>
	    所在部门：<input id="department" name="department"><br>
	   角色：<input id="role" name="role"><br>
     <input type="button" value="确定" onclick="confirmFun()"> <input type="reset" value="重置" onclick="resetFun()">
    </form>
</body>

</html>

(7)编辑人员信息界面updateuser.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="entity.UserInfo" %>
<%@ page import="dao.UserInfoDaoMrg" %>

<!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>修改</title>
</head>
<script>
	function confirmFun(){
		var x1 = document.getElementById("name").value;
		var x2 = document.getElementById("jobNumber").value;
		var x3 = document.getElementById("level").value;
		var x4 = document.getElementById("department").value;
		var x5 = document.getElementById("role").value;

		if(x1==""||isNaN(x1)||x2==""||isNaN(x2)||x3==""||isNaN(x3)||x4==""||isNaN(x4)
				||x5==""||isNaN(x5)){
			 alert("添加信息不完整");
			 return;
		}		
		document.getElementById("updform").submit();
	}
	
	function resetFun(){
		var spans = document.getElementsByTagName("input");
		for(var i=0;j<spans.length;i++){  
			var span = spans[i]; // input标签的数组
			document.getElementById(span.id).value ="";//
			console.info(span.id);
		}
	}
</script>
<body>
 <h3>修改页面</h3>
	<%
	UserInfo user = (UserInfo)request.getAttribute("user");	
	%>
    <form id="updform" action="updateuser" method="post">
               <input type="hidden" name="id" value="<%=user.getId()%>">
	               工号：<input name="jobNumber" value="<%=user.getJobNumber()%>"><br>
		    姓名：<input name="name" value="<%=user.getName()%>"> <br>
		    技术水平：<input name="level" value="<%=user.getLevel()%>"><br>
		    所在部门：<input name="department" value="<%=user.getDepartment()%>"><br>
		   角色：<input name="role" value="<%=user.getRole()%>"><br>
	    <input type="submit" value="确定"  onclick="confirmFun()">  <input type="reset" value="重置"  onclick="resetFun()">
    </form>
</body>
</html>

5、配置web.xml文件的信息如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>webexample</display-name>
  <welcome-file-list>
    <welcome-file>/logon.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
    <servlet-name>s1</servlet-name>
    <servlet-class>servlet.ActionServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>s1</servlet-name>
    <url-pattern>/logon</url-pattern>
  </servlet-mapping>
  
  <servlet>
    <servlet-name>s2</servlet-name>
    <jsp-file>/home.jsp</jsp-file>
  </servlet>
  <servlet-mapping>
    <servlet-name>s2</servlet-name>
    <url-pattern>/home</url-pattern>
  </servlet-mapping>
    
  <servlet>
    <servlet-name>s3</servlet-name>
    <servlet-class>servlet.UserListServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>s3</servlet-name>
    <url-pattern>/userlistright</url-pattern>
  </servlet-mapping>
  
  <servlet>
    <servlet-name>s4</servlet-name>
    <servlet-class>servlet.AddUserServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>s4</servlet-name>
    <url-pattern>/addright</url-pattern>
  </servlet-mapping>
  
    <servlet>
    <servlet-name>s5</servlet-name>
    <servlet-class>servlet.UpdateUserServlet</servlet-class>
  </servlet>
   <servlet-mapping>
    <servlet-name>s5</servlet-name>
    <url-pattern>/updateuser</url-pattern>
  </servlet-mapping>
   
   <servlet>
    <servlet-name>s6</servlet-name>
    <servlet-class>servlet.DeleteUserServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>s6</servlet-name>
    <url-pattern>/deleteUserServlet</url-pattern>
  </servlet-mapping>
  
   <servlet>
    <servlet-name>s7</servlet-name>
    <servlet-class>servlet.SelectUserServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>s7</servlet-name>
    <url-pattern>/selectUserServlet</url-pattern>
  </servlet-mapping>
  
</web-app>

6、对应的Java代码如下：
（1）util包下的DBUtil.java

package util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import org.junit.Test;

/**
 *  JDBC工具类：
 *  提供了获得连接，关闭连接的相关的方法
 * @author Administrator
 *
 */
public class DBUtil {	
	static Connection conn = null;			 
	static Statement stmt = null;

	//建立连接
	public static Connection getConnection() throws Exception{	
	    try {		
	    	Class.forName("com.mysql.jdbc.Driver");		
		    System.out.println("成功加载驱动程序");
		    conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/userdemo", "root", "root");
			System.out.println("数据库连接成功");
		} catch (Exception e) {
			System.out.println("未连接成功");
			e.printStackTrace();
		}
		return conn;
	}
}

（2）entity包下的User.java、UserInfo.java

（2.1） User.java类

package entity;

/**
 * 实体类
 * @author Administrator
 * 对应登陆界面
 */

public class User {
	private int id;
    private String username;
    private String pwd;
    private String name;
    private String gender;

	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 getPwd() {
		return pwd;
	}
	
	public void setPwd(String pwd) {
		this.pwd = pwd;
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public String getGender() {
		return gender;
	}
	
	public void setGender(String gender) {
		this.gender = gender;
	}
    
	@Override
	public String toString() {
		return "User [id=" + id + ", username=" + username + ", pwd=" + pwd
				+ ", name=" + name + ", gender=" + gender + "]";
	}
}

（2.2）UserInfo.java类

package entity;

/**
 * @author
 * 人员信息的实体类
 * 对应人员信息界面
 */
public class UserInfo {
	private Integer id;
    private String jobNumber;
    private String name;
    private String level;
    private String department;
    private String role;

	//初始化
    public UserInfo(Integer id ,String jobNumber,String name, String level, String department, String role) {
    	this.id = id;
    	this.jobNumber = jobNumber;
    	this.name = name;
		this.level = level;
		this.department = department;
		this.role = role;
	}
    
	//初始化
    public UserInfo(String jobNumber,String name, String level, String department, String role) {
		this.jobNumber = jobNumber;
    	this.name = name;
		this.level = level;
		this.department = department;
		this.role = role;
	}
    
    public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}
	public String getJobNumber() {
		return jobNumber;
	}
	public void setJobNumber(String jobNumber) {
		this.jobNumber = jobNumber;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}	
	public String getLevel() {
		return level;
	}
	public void setLevel(String level) {
		this.level = level;
	}
	public String getDepartment() {
		return department;
	}
	public void setDepartment(String department) {
		this.department = department;
	}
	public String getRole() {
		return role;
	}
	public void setRole(String role) {
		this.role = role;
	}
	
	@Override
	public String toString() {
		return "UserInfo [id=" + id + ", jobNumber=" + jobNumber + ", name="
				+ name + ", level=" + level + ", department=" + department
				+ ", role=" + role + "]";
	}
}

（3）dao包下的UserDao.java、UserInfoDaoMrg.java

（3.1） UserDao.java类

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import util.DBUtil;
import entity.User;

/**
 * @author
 * 对应登陆界面
 */
public class UserDao {

	public User findByUsername(String username){
		User user = null;       
		Connection conn = null;
		
		//获取连接    	
        try {
        	conn = DBUtil.getConnection();
        	//预处理语句
        	PreparedStatement prep = conn.prepareStatement("select * from userdemo where username=?");//username
			prep.setString(1, username);//查询sql语句中第一个“？”的位置			
			//遍历数据库
			ResultSet rst = prep.executeQuery();//rst.next()指针游标，输出之后其值会发生变化	
			if(rst.next()){
				System.out.println(rst.getInt("id"));
				user = new User();
				user.setId(rst.getInt("id"));//id
				user.setUsername(username);//username
				user.setPwd(rst.getString("pwd"));//pwd
				user.setName(rst.getString("name"));//name
				user.setGender(rst.getString("gender"));//gender
			}			
		} catch (Exception e) {			
			e.printStackTrace();//抛出异常
			System.out.println("查询失败");
//			DBUtil.close(conn);
		}
		return user;	
	}
}

（3.2）UserInfoDaoMrg.java 类

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.*;

import bean.Page;
import util.DBUtil;
import entity.User;
import entity.UserInfo;

/**
 * @author
 * 负责访问数据库
 */
public class UserInfoDaoMrg {
	
	List<UserInfo> userList = new ArrayList<>();  	
	UserInfo user = null;   
	
	//查找所有员工
	public List<UserInfo> getUserInfo(){		
        try {
        	//获取连接
        	Connection conn = DBUtil.getConnection();
        	//预处理语句
        	PreparedStatement prep = conn.prepareStatement("select * from userinfo");
			//遍历数据库
			ResultSet rst = prep.executeQuery();
			while(rst.next()){
				int id = rst.getInt("id");
				System.out.println("-----" + id);
				String jobNumber = rst.getString("jobNumber");
				String name = rst.getString("name");
				String technicalLevel = rst.getString("level");
				String department = rst.getString("department");
				String role = rst.getString("role");
				user = new UserInfo(id, jobNumber, name, technicalLevel, department, role);				
				userList.add(user);
			}			
			prep.close();
			conn.close();			
		} catch (Exception e) {	
			e.printStackTrace();//抛出异常  
			System.out.println("查询失败");
		}
        return userList;	
	}
	
	//添加
	 public void addUserInfo(String jobNumber, String name, String technicalLevel, String department, String role) {
		 try {
        	//获取连接
        	Connection conn = DBUtil.getConnection();
        	//预处理语句
        	String sql = "insert into userinfo (jobNumber,name,level,department,role) values (?, ?, ?, ?, ?)";
        	PreparedStatement prep = conn.prepareStatement(sql);
        	prep.setString(1, jobNumber);
        	prep.setString(2, name);
        	prep.setString(3, technicalLevel);
        	prep.setString(4, department);
        	prep.setString(5, role);
        	prep.executeUpdate();
        	prep.close();
        	conn.close();
		} catch (Exception e) {	
			e.printStackTrace();//抛出异常 （检查出现的问题)
			System.out.println("增加失败");
		}
	 }
	 
	 
	//加载员工信息，用于更新界面
	public UserInfo selectUserInfo(int id){
		UserInfo user = null;
		Connection con = null;
		PreparedStatement prep = null;
		ResultSet rst = null;
		try {
			con=DBUtil.getConnection();
			String sql = "select * from userinfo where id =?";
			prep = con.prepareStatement(sql);
			prep.setInt(1, id);
			rst = prep.executeQuery();
			while(rst.next()){
				String jobNumber = rst.getString("jobNumber");
				String name = rst.getString("name");
				String technicalLevel = rst.getString("level");
				String department = rst.getString("department");
				String role = rst.getString("role");
				user = new UserInfo(id, jobNumber, name, technicalLevel, department, role);				
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return user;
	}	
 	
	//更新数据库
	 public void updateUserInfo(Integer id, String jobNumber, String name, String level,String department, String role) {
		 try {
	        //获取连接
			Connection conn = DBUtil.getConnection();
			String sql = "update userinfo set jobnumber= ?, name = ?, level= ?, department= ?, role= ? where id= ?";
			//预处理语句
			PreparedStatement prep = conn.prepareStatement(sql);
        	prep.setString(1, jobNumber);
			prep.setString(2, name);
        	prep.setString(3, level);
        	prep.setString(4, department);
        	prep.setString(5, role);
        	prep.setInt(6, id);
     
        	//更新数据库
        	prep.executeUpdate();        	
        	prep.close();
        	conn.close();
        	
		} catch (Exception e) {	
			e.printStackTrace();//抛出异常
			System.out.println("更新失败");
		} 
	}
		 
	//删除数据库
	 public void deleteUserInfo(Integer id) {
		 try {
	        //获取连接
			Connection conn = DBUtil.getConnection();
			//预处理语句
			PreparedStatement prep = conn.prepareStatement("delete from userinfo where id=?");
			prep.setInt(1, id);
			prep.executeUpdate();
			prep.close();
        	conn.close();
		} catch (Exception e) {	
			e.printStackTrace();//抛出异常  //by tongshi
			System.out.println("删除失败");
		}
	}
	 
	//分页查找
	public List<UserInfo> findByPageNum(Page page){
		int begin = (page.getPageNum()-1)*page.getPageSize();//分页算法：确定起始页第一条记录，pageSize = 6  PageNum： 页码数	
		 System.out.println(page.getPageNum());
		 System.out.println(page.getPageSize());
		 System.out.println(page.getPageTotal());
		try {
			//获取连接
	    	Connection conn = DBUtil.getConnection();
	    	//预处理语句
	    	String sql = "select * from userinfo limit ?,?";
	    	PreparedStatement prep = conn.prepareStatement(sql);
			prep.setInt(1, begin); 
			prep.setInt(2, page.getPageSize());
			
			//遍历数据库
			ResultSet rst = prep.executeQuery();
			while(rst.next()){
				int id = rst.getInt("id");
				String jobNumber = rst.getString("jobNumber");
				String name = rst.getString("name");
				String technicalLevel = rst.getString("level");
				String department = rst.getString("department");
				String role = rst.getString("role");
				user = new UserInfo(id, jobNumber, name, technicalLevel, department, role);	
				userList.add(user);
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return userList;
	}
	
	//获取总记录数量
	public int getRecordsNum(){
		Connection con = null;
		PreparedStatement ps=null;
		ResultSet rs = null;
		int recordsNum = 0;
		try {
			con = DBUtil.getConnection();
			String sql = "select count(*) count from userinfo"; //获得表中记录数
			ps = con.prepareStatement(sql);
			rs = ps.executeQuery();
			while(rs.next()){
				recordsNum = rs.getInt("count");
			}
		} catch (Exception e) {
			
			e.printStackTrace();
		}
		return recordsNum;
	}
}

（4）bean包下的Page.java

package bean;

import dao.UserInfoDaoMrg;

public class Page {	   
	private int pageNum;//页码数		
	private int pageSize = 6;//每页显示数量,默认为3
	private int pageTotal;//总页数
	private int recordsNum;//总记录数

	UserInfoDaoMrg userDaoInfo = new UserInfoDaoMrg();
		
	public int getPageNum() {
		return pageNum;
	}
 
	public void setPageNum(int pageNum) {
		this.pageNum = pageNum;
	}
 
	public int getPageSize() {
		return pageSize;
	}
 
	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}
 
	public int getRecordsNum() {
		return recordsNum;
	}
 
	public void setRecordsNum(int recordsNum) {
		this.recordsNum = recordsNum;
	}
 
	public void setPageTotal(int pageTotal) {
		this.pageTotal = pageTotal;
	}
 
	public int getPageTotal(){
		recordsNum = userDaoInfo.getRecordsNum();
		int mod = recordsNum % pageSize;
		if(mod == 0){
			pageTotal=recordsNum/pageSize;
		}else{
			pageTotal=recordsNum/pageSize+1;
		}
		return pageTotal;
	}	     
}

（5）servlet包下的ActionServlet.java、AddUserServlet.java、DeleteUserServlet.java、SelectUserServlet.java、UpdateUserServlet.java、UserListServlet.java

（5.1）ActionServlet.java类：

package servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import dao.UserDao;
import entity.User;

public class ActionServlet extends HttpServlet {
	private static final long serialVersionUID = 3624434001049002202L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
		
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        
        PrintWriter out = response.getWriter();//输出在控制台
        
        //分享请求资源路径
        String uri = request.getRequestURI();
        String action = uri.substring(uri.lastIndexOf("/"));//截取子字符串
        System.out.println("URI为：" + action);
        
        if("/logon".equals(action)){
            //读取用户名和密码
            String userName = request.getParameter("username");//username为jsp中字段，即是：接收到前台传来的数据
            String password = request.getParameter("password");//password为jsp中字段
            
            //根据用户名和密码查询数据库中是否有这个用户
            UserDao ud = new UserDao();
            try {
                User user = ud.findByUsername(userName);
                if(user != null && password.equals(user.getPwd())){                	
                	//创建Session对象保存User对象
                    HttpSession session = request.getSession();
                    session.setAttribute("user", userName);

                    //登陆成功跳转指定页面
                    request.getRequestDispatcher("home").forward(request,response);
                }else{
                    out.print("用户名或者密码为空");
                    request.getRequestDispatcher("/webdexample").forward(request,response);
                }
            } catch (Exception e) {
                e.printStackTrace();
                throw new ServletException(e);
            }
        }
        out.close();
    }
	
	 protected void doPost(HttpServletRequest request, HttpServletResponse response)
			  throws ServletException, IOException {
	        doGet(request, response);
	 }
}

（5.2）AddUserServlet.java类

package 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 com.sun.xml.internal.bind.v2.model.core.ID;

import dao.UserInfoDaoMrg;
import entity.UserInfo;

/**
 * @author
 * 对应“增加”部分的按钮
 */
public class AddUserServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {		
		 request.setCharacterEncoding("utf-8");
	     response.setContentType("text/html;charset=utf-8");	
	     
	     //获得form表单属性
	     String jobNumber = request.getParameter("jobNumber");
	     String name = request.getParameter("name");
	     String level = request.getParameter("level");
	     String department = request.getParameter("department");
	     String role = request.getParameter("role");
	     
	     //servlet
	     request.setAttribute("jobNumber", jobNumber);
	     request.setAttribute("name", name);
	     request.setAttribute("technicalLevel", level);
	     request.setAttribute("department", department);
	     request.setAttribute("role", role);
	     
	     //更新数据库 
	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
		 ud.addUserInfo(jobNumber, name, level, department, role);   
	     request.getRequestDispatcher("userlistright").forward(request,response);// 对应servlet
	}
	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

（5.3）DeleteUserServlet.java类

package 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 util.DBUtil;
import dao.UserInfoDaoMrg;
import entity.UserInfo;

public class DeleteUserServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {		
		 request.setCharacterEncoding("utf-8");
	     response.setContentType("text/html;charset=utf-8");//response解决乱码问题	     
	     System.out.println("进入deleteservlet");
	     int id = Integer.parseInt(request.getParameter("id"));//从table（前端）中得到的id
	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
	     ud.deleteUserInfo(id);	 
		 request.getRequestDispatcher("userlistright").forward(request,response);
	}
	    	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

（5.4）SelectUserServlet.java类

package 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 dao.UserInfoDaoMrg;
import entity.UserInfo;

public class SelectUserServlet extends HttpServlet{
	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
		
		 request.setCharacterEncoding("utf-8");
	     response.setContentType("text/html;charset=utf-8");
	     
	     int id = Integer.parseInt(request.getParameter("id"));//从table（前端）中得到的id
	     System.out.println("-----------" + id);
	     
	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
		 UserInfo user = ud.selectUserInfo(id);
		 request.setAttribute("user", user);
	     request.getRequestDispatcher("updateuser.jsp").forward(request,response);	
	}
	
	 protected void doPost(HttpServletRequest request, HttpServletResponse response)
			  throws ServletException, IOException {
	        doGet(request, response);
	 }
}

（5.5）UpdateUserServlet.java类

package 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 com.sun.xml.internal.bind.v2.model.core.ID;

import dao.UserInfoDaoMrg;
import entity.UserInfo;

public class UpdateUserServlet extends HttpServlet{
	
	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {		
		 request.setCharacterEncoding("utf-8");
	     response.setContentType("text/html;charset=utf-8");
	     
	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
	     Integer id = Integer.parseInt(request.getParameter("id"));
	     String name = request.getParameter("name");
	     String jobNumber = request.getParameter("jobNumber");
	     String technicalLevel = request.getParameter("level");
	     String department = request.getParameter("department");
	     String role = request.getParameter("role"); 
	     
	     //更新数据库
	     ud.updateUserInfo(id, jobNumber, name, technicalLevel, department, role);   
	     request.getRequestDispatcher("userlistright").forward(request,response);
	}
	
	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
}

（5.6） UserListServlet.java类

package 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 bean.Page;
import dao.UserInfoDaoMrg;
import entity.UserInfo;

public class UserListServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
		
		 request.setCharacterEncoding("utf-8");
	     response.setContentType("text/html;charset=utf-8");
	     	     
	     //分页显示对应的代码
	     Page page = new Page();
	     String pageNum = request.getParameter("pageNum");
	     if(pageNum == null){
			page.setPageNum(1);
		 }else{
			page.setPageNum(Integer.parseInt(pageNum));
		 }	
	     
	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
	     
		 List<UserInfo> listUser = ud.findByPageNum(page);
		 request.setAttribute("list", listUser);//对应列表
		 request.setAttribute("page", page);//对应分页
	     request.getRequestDispatcher("userlistright.jsp").forward(request,response); //"userlistright.jsp" by workmate	
	     
//	     //不分页显示对应的代码
//	     UserInfoDaoMrg ud = new UserInfoDaoMrg();
//		 List<UserInfo> userList = ud.getUserInfo();		 
//		 request.setAttribute("list", userList);
//	     request.getRequestDispatcher("userlistright.jsp").forward(request,response); //"userlistright.jsp" by workmate		
	}
	
	 protected void doPost(HttpServletRequest request, HttpServletResponse response)
			  throws ServletException, IOException {
	        doGet(request, response);
	 }
}

jsp+servlet+jdbc实现对数据库简单的增删改查

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