程序代码：

package com.xxx.jdbcdemo.dao;

import java.awt.List;
import java.beans.Statement;
import java.sql.Connection;
import java.sql.Date;
import java.sql.ResultSet;
import java.text.SimpleDateFormat;
import java.util.ArrayList;

import javax.xml.crypto.Data;

import com.xxx.jdbcdemo.db.DBCConnection;
import com.xxx.jdbcdemo.javabean.User;

public class UserDaoImpl   {
//定义一个数据库连接的对象
    private DBCConnection dbConnection;

    //创建数据库连接的对象
    public UserDaoImpl(){
        dbConnection=new DBCConnection();
            }
    //插入数据
    public void insertUser(User user) throws Exception{
        Connection conn=dbConnection.getConnection();
        //得到执行sql语句的对象
        java.sql.Statement sta=conn.createStatement();
        //将日期时间格式化
        String registerTime=new SimpleDateFormat("yyyy-MM-"
                + "ddhh:mm:ss").format(user.getRegisterTime());
        //拼接sql语句
        String  insertSql="insert into "
                + "user(username,password,registerTime)";
        //开始执行sql语句
        int temp=sta.executeUpdate(insertSql);
        //关闭执行sql语句
        sta.close();
        dbConnection.closeConnection(conn);
        if(temp>0){
            System.out.println("插入数据成功");
        }else{
            System.out.println("插入数据失败");
        }
        
}
    //修改数据
    public void updataUserByID(User user) throws Exception{
        Connection conn=dbConnection.getConnection();
        //得到执行sql语句的对象
        java.sql.Statement sta=conn.createStatement();
        //拼接sql语句
        String updateSql="update user set username='"
            +user.getUsername()+"'password='"+user.getPassword()
            +"'age="+user.getAge()+"where id"+user.getId();
        //开始执行sql语句
        int temp=sta.executeUpdate(updateSql);        
        //关闭执行sql语句的对象
        sta.close();
        //关闭执行sql语句的对象
        sta.close();
        dbConnection.closeConnection(conn);
        if(temp>0){
            System.out.println("修改数据成功");
        }else{
            System.out.println("修改数据失败");
        }
    }
    public void deleteUserByID(int id)throws Exception{
        //打开数据库
        Connection conn=dbConnection.getConnection();
        //得到执行sql语句的对象
        java.sql.Statement sta=conn.createStatement();
        //拼接sql语句
        String deleteSql="delete from user where id="+id;
        //开始执行sql语句
        int temp=sta.executeUpdate(deleteSql);
        sta.close();
        dbConnection.closeConnection(conn);
        if(temp>0){
            System.out.println("删除数据成功");
        }else{
            System.out.println("删除数据失败");
        }
    }
    //查询一条数据
    public User selectUserByID(int id)throws Exception{
        //打开数据库连接
        Connection conn=dbConnection.getConnection();
        java.sql.Statement sta=conn.createStatement();
        //拼接sql语句
        String selectSql="select*from user where id="+id;
        //开始执行sql语句，返回一个结果集
        ResultSet res=sta.executeQuery(selectSql);
        //遍历结果集
        //如果有数据就获取数据
        User user=null;
        if(res.next()){
            int uid=res.getInt(1);
            String name=res.getString(2);
            String pass=res.getString(3);
            int age=res.getInt(4);
            Date date=res.getDate(5);
            //封装成一个user对象
            user=new User();
            user.setId(uid);
            user.setUsername(name);
            user.setPassword(pass);
            user.setAge(age);
            user.setRegisterTime(new java.util.Date(date.getTime()));
            }
        //关闭结果集
        res.close();
        //关闭执行sql的对象
        sta.close();
        //关闭数据路链接
        dbConnection.closeConnection(conn);
        return user;
    }
    public java.util.List<User> selectAllUsers() throws Exception{
        java.util.List<User> userlist=new ArrayList<User>();
        Connection conn=dbConnection.getConnection();
        java.sql.Statement sta=conn.createStatement();
        String selectSql="select *from user";
        ResultSet res=sta.executeQuery(selectSql);
        while(res.next()){
            User user=new User();
            user.setId(res.getInt("id"));
            user.setUsername(res.getString("username"));
            user.setPassword(res.getString("password"));
            user.setAge(res.getInt("age"));
            user.setRegisterTime(res.getDate("registerTime"));
            userlist.add(user);
            
        }
        res.close();
        sta.close();
        dbConnection.closeConnection(conn);
        return userlist;
    }
}

package com.xxx.jdbcdemo.javabean;

import  java.util.Date;

import javax.xml.crypto.Data;

public class User implements Serializable {
    private static final long serialiVersionUID=1L;
    private int id;
    private String username;
    private String password;
    private int age;
    private Date registerTime;
    
    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 getPassword(){
        return password;
    }
    public void setPassword(String password){
        this.password=password;
    }
    public int getAge(){
        return age;
    }
    public void setAge(int age){
        this.age=age;
    }
    public void setRegisterTime(Date registerTime){
        this.registerTime=registerTime;
    }
    public Date getRegisterTime() {
        // TODO 自动生成的方法存根
        return registerTime;
    }
    
    


}
[code]
package com.xxx.jdbcdemo.db;

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

public class DBCConnection {
    //数据库驱动名称
public static final String DRIVER_NAME=
"com.mysql.jdbc.Driver";
//数据库链接地址
public static final String URL="jdba:mysql://localhost:3306/test";
//登陆数据库用户名
public static final String USERNAME="root";
public static final String PASSWORD="123456";

//静态块
static{
    try{
        //加载数据库驱动类
        Class.forName(DRIVER_NAME);
        }catch(ClassNotFoundException e){
            throw new ExceptionInInitializerError(e);
        }
}
//获取数据库连接
public Connection getConnection(){
    Connection conn=null;
    try{
        //建立连接
        conn=DriverManager.getConnection(URL,USERNAME,PASSWORD);
        if(conn!=null){
            System.out.println("连接成功！");
        }else{
            System.out.println("连接失败！");
        }
    }catch(Exception e){
        e.printStackTrace();
    }
    return conn;
    
}
//关闭数据库链接
public void closeConnection(Connection conn){
    try{
        if(conn!=null){
            //关闭数据库
            //使用connection对象调用close
            conn.close();
            conn=null;
        }
        }catch(SQLException e){
            e.printStackTrace();
    }
}
}