数据库连接简易用户增，删，改，查（DAO模式实现）

简易用户增，删，改，查（DAO模式实现）：

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简单介绍：

• Conn.java：连接数据库
• UserDao.java(数据层)：放增，删，改，查的方法
• User.java：JavaBean定义，封装用户属性的类，注意命名要与表中变量名一致
• view.jsp：初始界面，进行选择
• Register.jsp：添加注册页面
• DoRegister.jsp：执行添加操作
• SelectUser.jsp：用来显示全部用户及查找，还可用于选择删除和修改操作
• DeleteUser.jsp：删除用户
• UpdateUser.jsp：修改用户
• DoUpdateUser.jsp：执行修改用户操作
  话不多说上代码：
• Conn.java

package com.JavaBean_zyd.conn;
import java.sql.*;
public class Conn {
   public Connection getConn() {
   	Connection conn=null;
   	//return conn;
   	try {
   		Class.forName("com.mysql.jdbc.Driver");
   		conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/testaa?characterEncoding=utf-8", "root", "123456");
   	} catch (Exception e) {
   		// TODO Auto-generated catch block
   		e.printStackTrace();
   	} 
   	return conn;
   }
}

• UserDao.java(数据层)

package com.JavaBean_zyd.dao;

import com.JavaBean_zyd.conn.*;
import com.JavaBean_zyd.user.*;
//import com.mysql.jdbc.Connection;
import java.sql.*;
import java.util.*;

//数据层Dao

public class UserDao {
  //添加用户方法
  public int InsertUser(User user) {
  	int rs=0;
  	try {
  	   Conn dbc=new Conn();
  	   Connection conn=dbc.getConn();
  	   String sql_insert="INSERT INTO user(username,password,type) VALUES (?,?,?) ";
  	   PreparedStatement pst = conn.prepareStatement(sql_insert);
         pst.setString(1,user.getUsername());
  	   pst.setString(2, user.getPassword());
  	   pst.setString(3,user.getType());
  	   rs=pst.executeUpdate();
  	   //rs.close();
  	   pst.close();
  	   conn.close();
  	}catch(Exception e){
  		e.printStackTrace();
  	}
  	return rs;
  }	
  //查询的方法
  public List<User> SelectUser() {
  	List<User> list = new ArrayList<User>();
  	ResultSet rs = null;
  	try {
  	   Conn dbc=new Conn();
  	   Connection conn=dbc.getConn();
  	   String sql_select="select * from user ";
  	   PreparedStatement pst = conn.prepareStatement(sql_select);
  	   rs=pst.executeQuery();
  	   while(rs.next()) {
  		   User user = new User();
  		   user.setId(rs.getString("id"));
  		   user.setUsername(rs.getString("username"));
  		   user.setPassword(rs.getString("password"));
  		   user.setType(rs.getString("type"));
  		   list.add(user);
  	   }
  	   rs.close();
  	   pst.close();
  	   conn.close();
  
  	}catch(Exception e){
  		e.printStackTrace();
  	}
  	return list;
  }

  	//删除用户方法
  	public int DeleteUser(User user) {
  		int rs=0;
  		try {
  		   Conn dbc=new Conn();
  		   Connection conn=dbc.getConn();
  		   String sql_delete="delete from user where id = ?";
  		   PreparedStatement pst = conn.prepareStatement(sql_delete);
  	       pst.setString(1,user.getId());
  		   rs=pst.executeUpdate();
  		   //rs.close();
  		   pst.close();
  		   conn.close();
  		}catch(Exception e){
  			e.printStackTrace();
  		}
  		return rs;
  	}
  	
  	//查找id方法
  	public User SelectUserId(User user){
  		ResultSet rs=null;
  		User usera=new User();
  		try{
  			Conn dbc=new Conn();
  			Connection conn=dbc.getConn();
  			String sql_select_id="select * from user where id=?";
  			PreparedStatement pst=conn.prepareStatement(sql_select_id);
  			pst.setString(1, user.getId());
  			rs=pst.executeQuery();
  			if(rs.next()){
  				usera.setId(rs.getString("id"));
  				usera.setUsername(rs.getString("username"));
  				usera.setPassword(rs.getString("password"));
  				usera.setType(rs.getString("type"));	
  			}
  			rs.close();
  			pst.close();
  			conn.close();
  			}
  			catch(Exception e){
  				e.printStackTrace();					
  			}		
  		return usera;
  	}		
  	//修改更新user类
  	public int UpdateUser(User user){
  		
  		int rs=0;
  		try{
  		Conn dbc=new Conn();
  		Connection conn=dbc.getConn();
  		String sql_insert="update user set username=?,password=? where id=?";
  		PreparedStatement pst=conn.prepareStatement(sql_insert);
  		pst.setString(1, user.getUsername());
  		pst.setString(2, user.getPassword());
  		pst.setString(3, user.getId());
  		rs=pst.executeUpdate();
  		}
  		catch(Exception e){
  			e.printStackTrace();				
  		}
  		return rs;
  	}
  
  	//登录方法（根据姓名与密码）
  	public User LoginUser(User user){
  		User usera=new User();
  		ResultSet rs=null;
  		try{
  			Conn dbc=new Conn();
  			Connection conn=dbc.getConn();
  			String sql_select="select * from user where username=? and password=?";
  			PreparedStatement pst=conn.prepareStatement(sql_select);
  			pst.setString(1, user.getUsername());
  			pst.setString(2, user.getPassword());
  			rs=pst.executeQuery();
  			if(rs.next()){
  				
  				usera.setId(rs.getString("id"));
  				usera.setUsername(rs.getString("username"));
  				usera.setPassword(rs.getString("password"));
  				usera.setType(rs.getString("type"));						
  			}
  			}
  			catch(Exception e){
  				e.printStackTrace();		
  			}		
  		return usera;
  	}
}

• User.java

package com.JavaBean_zyd.user;

public class User {
   private String id;
   public String getId() {
   	return id;
   }
   public void setId(String id) {
   	this.id = id;
   }
   public String getUsername() {
   	return username;
   }
   public void setUsername(String username) {
   	this.username = username;
   }
   public String getPassword() {
   	return password;
   }
   public void setPassword(String password) {
   	this.password = password;
   }
   public String getType() {
   	return type;
   }
   public void setType(String type) {
   	this.type = type;
   }
   private String username;
   private String password;
   private String type;	
}
 

• view.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
   pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>选择界面</title>
</head>
<body>
   <center>
 <h3>javaBean选择界面（增删改查）</h3>
 <hr>
   <table border="1">
    <tr>
   		<td><a href="Register.jsp">**添加用户**</a></td>
   	</tr>
   	<tr>
   		<td><a href=" SelectUser1.jsp">**删除用户**</a></td>
   	</tr>
   	<tr>
   		<td><a href="SelectUser1.jsp">**修改用户**</a></td>
   	</tr>
   	<tr>
   		<td><a href="SelectUser1.jsp">**显示用户**</a></td>
   	</tr>
   </table>  
 </center>   
</body>
</html>

• Register.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录界面（数据库）</title>
<script language="javascript">
function check(){
	var password=form.password.value;
	if(password==""){
		alert("密码不能为空！！！");
		form.password.focus();
		return;
	}
}
</script>
</head>
<body>
<center>
  <h1>添加用户</h1>
  <hr>
  <%--<form action="DoRegl.jsp" method="post" name="form" onsubmit="return check()"> --%>
    <form action="DoRegister.jsp" method="post" name="form" onsubmit="return check()">
    <table border="1">
     <tr>
    <td>用户名：</td>
    <td><input type="text" name="username" value=""></td></tr>
    <tr>
    <td>密码：</td>
    <td><input type="password" name="password" value=""></td></tr>
     <tr>
     <td>类型：</td>
     <td><select name="type">
        <option value="Admin">Admin</option>
        <option value="User">User</option>
        </select></td>
  </tr>
    <tr>
    <td><input type="submit" value="登录"/>
    <input type="reset" value="重置"/></td>   
    </tr>
    </table>
   </form>
  </center> 
</body>
</html>

• DoRegister.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="com.JavaBean_zyd.dao.*,java.util.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>添加业务层</title>
</head>
<body>
   <%request.setCharacterEncoding("utf-8"); %>
   <jsp:useBean id="user" class="com.JavaBean_zyd.user.User"/>
   <jsp:setProperty property="*" name="user"/> 
   <%=user.getUsername() %>  添加成功！     <%--测试输出 --%>
   <%
     UserDao userinsert = new UserDao();
     int rs = userinsert.InsertUser(user);
     if(rs!=0){
    	 out.println("成功添加"+rs+"条记录！！！");
    	 //response.sendRedirect("SelectUser1.jsp");
     }
     /*else{
    	 response.sendRedirect("Register.jsp");
     }*/
     
   %>
  <br>
	<a href="view.jsp"><font size="3">返回选择界面</font></a>
</body>
</html>

• SelectUser.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="com.JavaBean_zyd.user.*,com.JavaBean_zyd.dao.*,java.util.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>查找业务层</title>
</head>
<body>

 

<%
  UserDao userselect = new UserDao();
  List<User> listall = new ArrayList<User>();
  listall = userselect.SelectUser();//参数应该写什么
  Iterator<User> iter = listall.iterator();
  
%>
  <table border="1">  
 
  <tr><td>用户名</td><td>密码</td><td>类型</td></tr>
  <%
   while(iter.hasNext()){
	   User user = iter.next();
	   %>
	   <tr>
	       <td><%=user.getUsername() %></td> 
	       <td><%=user.getPassword() %></td>
	       <td><%=user.getType() %></td>
	       <td><a href="DeleteUser.jsp?id=<%=user.getId()%>">删除操作</a></td>
	       <td><a href="UpdateUser.jsp?id=<%=user.getId()%>">修改操作</a></td>
	      
	   </tr><%
	   
     }%>
  </table>
	       <br><a href="view.jsp"><font size="3">返回首页</font></a>
</body>
</html>

• DeleteUser.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="com.JavaBean_zyd.user.*,com.JavaBean_zyd.dao.*,java.util.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>查找业务层</title>
</head>
<body>

 

<%
  UserDao userselect = new UserDao();
  List<User> listall = new ArrayList<User>();
  listall = userselect.SelectUser();//参数应该写什么
  Iterator<User> iter = listall.iterator();
  
%>
  <table border="1">  
 
  <tr><td>用户名</td><td>密码</td><td>类型</td></tr>
  <%
   while(iter.hasNext()){
	   User user = iter.next();
	   %>
	   <tr>
	       <td><%=user.getUsername() %></td> 
	       <td><%=user.getPassword() %></td>
	       <td><%=user.getType() %></td>
	       <td><a href="DeleteUser.jsp?id=<%=user.getId()%>">删除操作</a></td>
	       <td><a href="UpdateUser.jsp?id=<%=user.getId()%>">修改操作</a></td>
	      
	   </tr><%
	   
     }%>
  </table>
	       <br><a href="view.jsp"><font size="3">返回首页</font></a>
</body>
</html>

• UpdateUser.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"  import="com.JavaBean_zyd.user.*,com.JavaBean_zyd.dao.*,java.util.*,java.sql.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
   <% 
   UserDao userselectid=new UserDao();
   User user=new User();
   user.setId(request.getParameter("id"));
   User usera=new User();
   usera=userselectid.SelectUserId(user);
   
   %>
   <form action="DoUpdateUser.jsp?id=<%=usera.getId()%>" method="post">
               用户名：<input type="text" name="username" value="<%=usera.getUsername()%>">
               密码：<input type="text" name="password" value="<%=usera.getPassword()%>">
               用户类型：<input type="text" name="type" value="<%=usera.getType()%>">
       <input type="submit" value="修改">
  </form>
</body>
</html>

• DoUpdateUser.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"   import="com.JavaBean_zyd.user.*,com.JavaBean_zyd.dao.*,java.util.*,java.sql.*"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
   <% 
   request.setCharacterEncoding("utf-8");
   String id=request.getParameter("id"); 
   %>
   <jsp:useBean id="usera" class="com.JavaBean_zyd.user.User"></jsp:useBean>
   <jsp:setProperty property="*" name="usera"></jsp:setProperty>
 
  <%
  usera.setId(request.getParameter("id"));  
  UserDao userupdate=new UserDao();
  int rs=userupdate.UpdateUser(usera);
  if(rs!=0){
    response.sendRedirect("SelectUser1.jsp");
    }
    else{
    out.println("更新失败");
    }
   %>
</body>
</html>

！！！截图！！！