day05 数据库增删改查

1 配置文件

#这是一个数据库配置文件
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://192.168.110:3306/db01?&useSSL=false//去掉ssl警告
jdbc.username=root
jdbc.password=123456

2 连接池类

package com.yuxhu.jdbcTask;

import java.io.IOException;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import org.apache.commons.dbcp2.BasicDataSource;

public class DBUtilPool {
    static String driver;
    static String url;
    static String username;
    static String password;
    static BasicDataSource bds;
    //静态加载
    static{
        String accountConfig = "com/yuxhu/config/account.properties";
        Properties pro = new Properties();
        try {
            //加载外面配置文件
            pro.load(DBUtilPool.class.getClassLoader().getResourceAsStream(accountConfig));
            driver = pro.getProperty("jdbc.driver");
            url = pro.getProperty("jdbc.url");
            username = pro.getProperty("jdbc.username");
            password = pro.getProperty("jdbc.password");
            //建立连接池
            bds = new BasicDataSource();
            bds.setDriverClassName(driver);
            bds.setUrl(url);
            bds.setUsername(username);
            bds.setPassword(password);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //获取连接
    public static Connection getConnection(){
        Connection conn = null;
        if(bds == null){
            System.out.println("连接池为空！");
            return null;
        }
        try {
            conn = bds.getConnection();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return conn;
    }
    //关闭连接
    public static void closeConnection(Connection conn){
        if(conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

3 定义接口以及接口实现类

package com.yuxhu.jdbcTask;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public interface FunctionInterface {
    public boolean Login(String username, String password); //登陆
    public boolean Add(String username, String password);//增加用户
    public boolean Delete(String username);//删除用户
    public boolean modify(String option, String username, String newName);//修改用户
    public boolean search(String username);//查找用户
}

class Function implements FunctionInterface{
    Connection conn;
    PreparedStatement ps;
    
    // 登陆
    public boolean Login(String username, String password) {
        // 连接池拿连接
        conn = DBUtilPool.getConnection();
        // 准备好的声明
        ps = null;
        boolean result = false;

        String sql = "select username, password from account where username = ?";

        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1, username);

            // 执行声明
            ResultSet rs = ps.executeQuery();

            // 判断是否有查询那结果
            if (rs.next()) {
                if (!(rs.getString(2).equals(password))) {
                    System.out.println("密码错误,请重新登陆！");
                    result = false;
                }else{
                    System.out.println("登陆成功，请输入你的操作选项：");
                    result = true;
                }
            }else {
                System.out.println("账号错误,请重新登陆！");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        // 关闭
        finally {
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            DBUtilPool.closeConnection(conn);
        }
        return result;
    }
    
    
    // 增加用户
    @Override
    public boolean Add(String username, String password) {
        // 连接池拿连接
        conn = DBUtilPool.getConnection();
        // 准备好的声明
        ps = null;
        boolean result = false;

        String sql = "insert into account (username, password) value ( ? , ? )";

        try {
            ps = conn.prepareStatement(sql);
            ps.setString(1, username);
            ps.setString(2, password);

            try {
                // 执行声明
                int rs = ps.executeUpdate();

                // 判断是否有查询那结果
                if (rs != 0) {
                    result = true;
                    System.out.println("添加用户成功");
                } else {
                    throw new SQLException();
                }

            } catch (SQLException e) {
                System.out.println("用户名已存在，添加失败，请重试");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        // 关闭
        finally {
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            DBUtilPool.closeConnection(conn);
        }
        return result;
    }
    // 删除用户
    @Override
    public boolean Delete(String username) {
        if(username.equals("adm")){
            System.out.println("不能删除管理员！");
            return false;
        }
        // 连接池拿连接
        conn = DBUtilPool.getConnection();
        // 准备好的声明
        ps = null;
        boolean result = false;
        
        try {
            String sql = null;
            if(!(username.equals("all"))){
                sql = "delete from account where username = ?";
                ps = conn.prepareStatement(sql);
                ps.setString(1, username);
            }else if(username.equals("all")){
                sql = "delete from account where username <> ?";
                ps = conn.prepareStatement(sql);
                ps.setString(1, "adm");
            }
            
            try {
                // 执行声明
                int rs = ps.executeUpdate();

                // 判断是否有查询那结果
                if (rs != 0) {
                    result = true;
                    System.out.println("删除用户成功");
                } else {
                    throw new SQLException();
                }

            } catch (SQLException e) {
                System.out.println("用户名不存在，删除失败，请重试");
            }

        } catch (SQLException e) {
            e.printStackTrace();
        }
        // 关闭
        finally {
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            DBUtilPool.closeConnection(conn);
        }
        return result;
    }
    
    // 修改用户
    @Override
    public boolean modify(String option, String username, String newName) {
        // 连接池拿连接
        conn = DBUtilPool.getConnection();
        // 准备好的声明
        ps = null;
        boolean result = false;
        
        //判断用户名是否存在
        String exist = "select username from account where username = ?";
        try {
            ps = conn.prepareStatement(exist);
            ps.setString(1, username);
            ResultSet rs = ps.executeQuery();
            if(!(rs.next())){
                System.out.println("要修改的用户名不存在! 请重试");
                return false;
            }
            ps.close();
        } catch (SQLException e1) {
            e1.printStackTrace();
        }

        String sql = null;
        String msg = null;
        if (option.equals("1")) {
            sql = "update account set username = ? where username = ?";
            msg = "修改用户名成功！";
        }
        if (option.equals("2")) {
            sql = "update account set password = ? where username = ?";
            msg = "修改密码成功！";
        }

        if (sql != null) {
            try {
                ps = conn.prepareStatement(sql);
                ps.setString(1, newName);
                ps.setString(2, username);
                try {
                    // 执行声明
                    int rs = ps.executeUpdate();

                    // 判断是否有查询那结果
                    if (rs != 0) {
                        result = true;
                        System.out.println(msg);
                    }
                } catch (SQLException e) {
                    System.out.println("新用户名重名，修改失败，请重试");
                }

            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        // 关闭
        try {
            ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        DBUtilPool.closeConnection(conn);

        return result;
    }
    //查找用户
    @Override
    public boolean search(String username) {
        boolean result = false;
        conn = DBUtilPool.getConnection();
        String sql = "select username, password from account where username like ?";
        try {
            if(username.equals("all")){
                username = "%";
            }
            ps = conn.prepareStatement(sql);
            ps.setString(1, username + "%");
            ResultSet rs = ps.executeQuery();

            if(!(rs.next())){
                System.out.println("没有找到此用户！请重试！");
                return false;
            }else{
                rs.previous();
                System.out.println("你查看的用户信息如下：");
            }

            while (rs.next()) {
                System.out.println("用户名：" + rs.getString(1) + "\t密码：" + rs.getString(2));
                result = true;
            }

        } catch (SQLException e) {
            e.printStackTrace();
        }
        // 关闭
        try {
            ps.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        DBUtilPool.closeConnection(conn);
        return result;
    }
}

4 测试

package com.yuxhu.jdbcTask;

import java.util.Scanner;

public class LoginRegister {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        Function fun = new Function();
        
        boolean result = false;
        while(!result){
            System.out.println("账号：");
            String username = input.nextLine();
            System.out.println("密码：");
            String password = input.nextLine();
            //1.登陆
            result = fun.Login(username, password);
        }
        
        while(result){
            System.out.println("1.增加用户");
            System.out.println("2.删除用户");
            System.out.println("3.修改用户");
            System.out.println("4.查找用户");
            System.out.println("5.退出系统");
            
            String option = input.next();
            
            //增加用户
            if (option.equals("1")) {
                boolean flag = false;
                while (!flag) {
                    System.out.println("请输入要添加的用户名：(main 返回主菜单)");
                    String username = input.next();
                    if(username.equals("main")){
                        break;
                    }
                    System.out.println("请输入要添加的用户名密码：(main 返回主菜单)");
                    String password = input.next();
                    if(password.equals("main")){
                        break;
                    }
                    flag = fun.Add(username, password);
                }
            }
            
            //删除用户
            if(option.equals("2")){
                boolean flag = false;
                while (!flag) {
                    System.out.println("请输入要删除的用户名：(main 返回主菜单, all 删除全部)");
                    String username = input.next();
                    if(username.equals("main")){
                        break;
                    }
                    flag = fun.Delete(username);
                }
            }
            //修改用户  
            if(option.equals("3")){
                boolean flag = false;
                while (!flag) {
                    System.out.println("请输入你要修改的用户名：(main 返回主菜单)");
                    String username = input.next();
                    if(username.equals("main")){
                        break;
                    }
                    System.out.println("请输入你要修改的选项：1.用户名 2.密码 (main 返回主菜单)");
                    String num = input.next();
                    if(num.equals("main")){
                        break;
                    }
                    if(num.equals("1")){
                        System.out.println("请输入新的用户名：(main 返回主菜单)");
                        String newName = input.next();
                        if(newName.equals("main")){
                            break;
                        }
                        flag = fun.modify(num,username,newName);
                    }
                    if(num.equals("2")){
                        System.out.println("请输入新的密码：(main 返回主菜单)");
                        String password = input.next();
                        if(password.equals("main")){
                            break;
                        }
                        flag = fun.modify(num,username,password);
                    }
                }
            }
            //查找用户
            if(option.equals("4")){
                boolean flag = false;
                while(!flag){
                    System.out.println("请输入你要查看的用户名：(all查看全部)");
                    
                    String username = input.next();
                    flag = fun.search(username);
                }
            }
            
            //退出系统
            if(option.equals("5")){
                System.out.println("已退出系统");
                result = false;
            }
        }
        //关闭Scanner
        input.close();
    }
}