Service开发流程（转账业务）

快来打我* 2024-03-23 17:46 102阅读 0赞

## Service开发流程（转账业务） ##

#### 一、业务需求和逻辑 ####

（1）业务需求：

*  一个账户向另一个账户转账

（2）业务逻辑：

1.  首先在数据库中查询转账账号是否存在
2.  然后在数据库中查询转账账号密码是否存在
3.  再验证转账账号的余额是否足够转账
4.  再验证收款账号是否存在
5.  执行转账操作，转账账号余额减少，收款账号余额增加（减少的金额与增加的金额相等）

#### 二、业务实现步骤 ####

提前准备：创建lib目录，将mysql架包文件配好

创建包列表：

![在这里插入图片描述][1e44af57cbb94683bf0a864798a3c43b.png_pic_center]

##### 1、创建表account #####

CREATE TABLE IF NOT EXISTS `account`(
    `cardNo` VARCHAR(20) PRIMARY KEY COMMENT '卡号',
    `password` VARCHAR(20) NOT NULL COMMENT '密码',
    `name` VARCHAR(20) NOT NULL COMMENT '名称',
    `balance` DOUBLE NOT NULL COMMENT '账户余额'
    );

##### 2、向account表中插入数据 #####

INSERT INTO account VALUES('6001','123456','zhangsan',10000);
    INSERT INTO account VALUES('6002','123456','lisi',5000);

##### 3、封装实体类Account #####

package com.bdqn.entity;
    
    
    /*entity实体类Account类
     */
    
    public class Account {
        
        /** 账号 */
        private String cardNo;
        /** 密码 */
        private String password;
        /** 用户名 */
        private String name;
        /** 账户余额 */
        private double balance;
    
        // 无参构造方法
        public Account() {
        
            super();
        }
    
        // 有参构造方法
        public Account(String cardNo, String password, String name, double balance) {
        
            super();
            this.cardNo = cardNo;
            this.password = password;
            this.name = name;
            this.balance = balance;
        }
    
        // getXxx()/setXxx()方法
        public String getCardNo() {
        
            return cardNo;
        }
    
        public void setCardNo(String cardNo) {
        
            this.cardNo = cardNo;
        }
    
        public String getPassword() {
        
            return password;
        }
    
        public void setPassword(String password) {
        
            this.password = password;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public double getBalance() {
        
            return balance;
        }
    
        public void setBalance(double balance) {
        
            this.balance = balance;
        }
    
        // 重写Object类中的toString()方法
        @Override
        public String toString() {
        
            return "cardNo=" + cardNo + ", password=" + password + ", name=" + name
                    + ", balance=" + balance;
        }
    
    
    }

##### 4、 编写AccountDao接口 #####

这里呢，我们采用通过接口去定义抽象方法，目的是为了防止在实际的开发过程中呢，大家因为方法名不同导致合作效率低。

package com.bdqn.AccountDaoImpl;
    
    import com.bdqn.entity.Account;
    
    import java.util.List;
    
    public interface AccountDao {
        
        //增
        int insert(Account account);
        //删
        int delete(String cardNo);
        //改
        int update(Account account);
        //查单个
        Account select(String cardNo);
        //查所有
        List<Account> selectAll();
    }

##### 5.编写AccountDaoImpl类（Dao层代码） #####

package com.bdqn.AccountDaoImpl;
    
    import com.bdqn.entity.Account;
    import com.bdqn.utils.DBUtils;
    
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.ArrayList;
    import java.util.List;
    
    public class AccountDaoImpl implements AccountDao {
        
        @Override
        public int insert(Account account) {
        
            Connection connection = null;
            PreparedStatement preparedStatement = null;
    
            //准备SQL语句
            String sql = "INSERT INTO `account` (cardNo,password,`name`,balance) VALUES (?,?,?,?);";
            connection = DBUtils.getConnection();
            try {
        
                preparedStatement = connection.prepareStatement(sql);
                //绑定参数赋值
                preparedStatement.setString(1,account.getCardNo());
                preparedStatement.setString(2,account.getPassword());
                preparedStatement.setString(3,account.getName());
                preparedStatement.setDouble(4,account.getBalance());
    
                //执行SQL语句
                int result = preparedStatement.executeUpdate();
    
                return result;
            } catch (SQLException e) {
        
                throw new RuntimeException(e);
            }finally {
        
                DBUtils.closeAll(connection,preparedStatement,null);
            }
    
        }
    
        @Override
        public int delete(String cardNo) {
        
            Connection connection = null;
            PreparedStatement preparedStatement = null;
    
            //准备SQL语句
            String sql = "DELETE *FROM WHERE cardNo=?;";
            connection = DBUtils.getConnection();
            try {
        
                preparedStatement = connection.prepareStatement(sql);
                //绑定参数赋值
                preparedStatement.setString(1,cardNo);
                //执行sql语句
                int result =preparedStatement.executeUpdate();
    
                return result;
            } catch (SQLException e) {
        
                throw new RuntimeException(e);
            }finally {
        
                DBUtils.closeAll(connection,preparedStatement,null);
            }
        }
    
        @Override
        public int update(Account account) {
        
            Connection connection = null;
            PreparedStatement preparedStatement = null;
            //准备SQL语句
            String sql = "UPDATE `account` SET password=?,`name`=?,balance=? WHERE cardNo=?;";
            connection = DBUtils.getConnection();
            try {
        
                preparedStatement = connection.prepareStatement(sql);
                //绑定参数赋值
                preparedStatement.setString(1,account.getPassword());
                preparedStatement.setString(2,account.getName());
                preparedStatement.setDouble(3,account.getBalance());
                preparedStatement.setString(4,account.getCardNo());
    
                //执行sql语句
                int result = preparedStatement.executeUpdate();
                return result;
            } catch (SQLException e) {
        
                throw new RuntimeException(e);
            }finally {
        
                DBUtils.closeAll(connection,preparedStatement,null);
            }
    
        }
    
        @Override
        public Account select(String cardNo) {
        
            Account account = null;
            Connection connection = null;
            PreparedStatement preparedStatement = null;
            ResultSet resultSet = null;
            //准备sql语句
            String sql = "SELECT *FROM `account` WHERE cardNo=?;";
            connection = DBUtils.getConnection();
            try {
        
                preparedStatement = connection.prepareStatement(sql);
                //绑定参数赋值
                preparedStatement.setString(1,cardNo);
    
                //执行SQL语句
                resultSet = preparedStatement.executeQuery();
    
                if(resultSet.next()){
        
                    String cardNo1= resultSet.getString("cardNo");
                    String password = resultSet.getString("password");
                    String name = resultSet.getString("name");
                    Double balance = resultSet.getDouble("balance");
                    account = new Account(cardNo1,password,name,balance);
                }
                return account;
            } catch (SQLException e) {
        
                throw new RuntimeException(e);
            }finally {
        
                DBUtils.closeAll(connection,preparedStatement,null);
            }
    
        }
    
        @Override
        public List<Account> selectAll() {
        
            Connection connection = null;
            PreparedStatement preparedStatement = null;
            ResultSet resultSet =null;
            Account account = null;
            List<Account> list = new ArrayList<Account>();
            //准备SQL语句
            String sql = "SELECT *FROM `account` WHERE cardNo=?;";
            connection = DBUtils.getConnection();
            try {
        
                preparedStatement = connection.prepareStatement(sql);
              //执行SQL语句
                resultSet = preparedStatement.executeQuery();
    
                while (resultSet.next()){
        
                    String cardNo = resultSet.getString("cardNo");
                    String password= resultSet.getString("password");
                    String name = resultSet.getString("name");
                    Double balance = resultSet.getDouble("balance");
                    account = new Account(cardNo,password,name,balance);
                    list.add(account);
                }
                return list;
            } catch (SQLException e) {
        
                throw new RuntimeException(e);
            }finally {
        
                DBUtils.closeAll(connection,preparedStatement,null);
            }
    
        }
    }

##### 6.编写AccountService接口代码： #####

package com.bdqn.service;
    
    public interface AccountService {
        
        void transfer(String fromNo, String password, String toNo, double money);
    }

##### 7.编写AccountServiceImpl类（业务层代码） #####

package com.bdqn.service;
    
    import com.bdqn.AccountDaoImpl.AccountDaoImpl;
    import com.bdqn.entity.Account;
    
    public class AccountServiceImpl implements AccountService {
        
        /**
         * 转账业务
         *
         * @param fromNo   转账人账号
         * @param password 转账人账号密码
         * @param toNo     收款人账号
         * @param money    转账金额
         */
        @Override
        public void transfer(String fromNo, String password, String toNo, double money) {
        
            AccountDaoImpl accountDaoImpl = new AccountDaoImpl();
    
            try {
        
                // 1.验证fromNo账号是否存在
                Account fromAccount = accountDaoImpl.select(fromNo);
                if (fromAccount == null) {
        
    
                    throw new RuntimeException("卡号不存在！");
                }
    
                //2.验证password密码是否正确
                if (!fromAccount.getPassword().equals(password)) {
        
    
                    throw new RuntimeException("密码错误！");
                }
                //3.验证余额是否充足
                if (fromAccount.getBalance() < money) {
        
    
                    throw new RuntimeException("抱歉,您的余额不足！");
                }
                //4.验证收款人卡号是否存在
                Account toAccount = accountDaoImpl.select(toNo);
                if (toAccount == null) {
        
                    throw new RuntimeException("对方卡号不存在！");
                }
                //5.减少fromNo账号的余额
                fromAccount.setBalance(fromAccount.getBalance() - money);
                accountDaoImpl.update(fromAccount);
    
                // 6.增加toNo账号的余额
                toAccount.setBalance(toAccount.getBalance() + money);
                accountDaoImpl.update(toAccount);
                System.out.println("转账成功");
            } catch (Exception e) {
        
                System.out.println("转账失败");
                e.printStackTrace();
            }
        }
    }

##### 8.编写AccountTest，测试转账业务 #####

package com.bdqn.Test;
    
    import com.bdqn.service.AccountServiceImpl;
    
    public class AccountTest {
        public static void main(String[] args) {
            AccountServiceImpl accountServiceImpl = new AccountServiceImpl();
            accountServiceImpl.transfer("6001","123456","6002",2000);
        }
    }

##### 9.工具类（DBUtils） #####

目的：为了简便代码量，DBUtils工具类中定义了2个方法：

作用：1.getConnection()方法是为了获取SQL连接

2.closeAll()方法是为了释放缓存资源

package com.bdqn.utils;
    
    import java.sql.*;
    
    public class DBUtils {
        static {
    
            //注册驱动
            try {
                Class.forName("com.mysql.cj.jdbc.Driver");
            } catch (ClassNotFoundException e) {
                throw new RuntimeException(e);
            }
        }
    
        //获取连接
        public static Connection getConnection(){
            Connection connection = null;
            try {
                connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/jdbcdatabase","root","123456");
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
            return connection;
        }
    
        //释放资源
        public static void closeAll(Connection connection, Statement statement, ResultSet resultSet){
            if (resultSet!=null){
                try {
                    resultSet.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            if (statement!=null){
                try {
                    statement.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            if (connection!=null){
                try {
                    connection.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            }
        }
    }

[1e44af57cbb94683bf0a864798a3c43b.png_pic_center]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/14/84e9e91ff1994527bbceea406d05bf67.png