Java模拟银行转账(操作事务)

向右看齐 2022-05-29 23:24 302阅读 0赞

第一步：建立一张银行账户表 叫 BankAccount 并建立一个序列

id         number    pk         //用户id
    ano        varchar2(30)  uk     //用户卡号
    apassword  varchar2(30)         //用户密码
    aname      varchar2(30)         //用户名
    amoney     number               //余额

//创建银行用户表
    drop table bank_account;
    create table    bank_account(
         id    number  constraint   bank_account_id_pk   primary key,
         ano  varchar(30) constraint bank_account_ano_uk  unique,
         apassword  varchar(30), 
         aname   varchar(30),
         amoney  number
    );
    drop sequence bank_account_id_seq;
    create sequence    bank_account_id_seq;
    6.2 写一个java程序  用来开户   只要输入 账号                  密码     开户人的姓名   余额 
    开户信息如下                           6225880111887788     123456   zhangsan       99999999  
                                          6225880111887799     123456   lisi    9

第二步：创建Bean包，编写实体类

public class BankAccount {
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getAno() {
            return ano;
        }
        public void setAno(String ano) {
            this.ano = ano;
        }
        public String getAname() {
            return aname;
        }
        public void setAname(String aname) {
            this.aname = aname;
        }
        public String getApassword() {
            return apassword;
        }
        public void setApassword(String apassword) {
            this.apassword = apassword;
        }
        public String getAmoney() {
            return amoney;
        }
        public void setAmoney(String amoney) {
            this.amoney = amoney;
        }
        @Override
        public String toString() {
            return "BankAccount [id=" + id + ", ano=" + ano + ", aname=" + aname + ", apassword=" + apassword + ", amoney="
                    + amoney + "]";
        }
        public BankAccount(String ano, String aname, String apassword, String amoney) {
            super();
            this.ano = ano;
            this.aname = aname;
            this.apassword = apassword;
            this.amoney = amoney;
        }
        public BankAccount(int id, String ano, String aname, String apassword, String amoney) {
            super();
            this.id = id;
            this.ano = ano;
            this.aname = aname;
            this.apassword = apassword;
            this.amoney = amoney;
        }
        public BankAccount() {
            super();
            // TODO Auto-generated constructor stub
        }
        private int id;
        private String ano;
        private String aname;
        private String apassword;
        private String amoney;
    }

第三步：创建账号，编写开户程序

import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.SQLException;
    import java.util.Scanner;
    import com.xdl.util.JdbcUtil2;
    
    public class CreateBankAccount {
        public static void main(String[] args) {
             Scanner  sc = new Scanner(System.in);
             System.out.println("请输入开户的卡号:");
             String  ano = sc.nextLine();
             System.out.println("请输入开户的名字:");
             String  aname = sc.nextLine();
             System.out.println("请输入开户的密码:");
             String  apassword = sc.nextLine();
             System.out.println("请输入开户的钱数:");
             String  smoney = sc.nextLine();
             //double  amoney = Double.parseDouble(smoney);
             // 把输入的数据 包装成对象  
             BankAccount  ba = new BankAccount(ano, aname, apassword, smoney);
             Connection  conn = null;
             PreparedStatement  ps = null;
             conn = JdbcUtil2.getConnection();
             String  sql="insert into bank_account values(bank_account_id_seq.nextval,?,?,?,?)";
             try {
                ps = conn.prepareStatement(sql);
                ps.setString(1, ba.getAno());
                ps.setString(2, ba.getApassword());
                ps.setString(3, ba.getAname());
                ps.setDouble(4, Double.parseDouble(ba.getAmoney()));
                int rows = ps.executeUpdate();
                if(rows == 1) {
                    System.out.println("开户成功");
                }else{
                    System.out.println("开户失败");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }finally{
                JdbcUtil2.releaseResource(conn, ps, null);
            }
        }
    }

第四步：编写转账程序

1、先登录，登录成功才可以执行转账程序

2、转账逻辑时，链接会自动进行数据的提交，这样万一转入的账户不成功，则无法回退之前的操作，为了解决 操作语句 需要同时成功或同事失败 则需要关闭连接的自动提交

禁止自动提交 conn.setAutoCommit(false);  
语句都成功 就提交 conn.commit() ；否则进行回滚 conn.rollback();

import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.Scanner;
    import com.xdl.util.JdbcUtil2;
    
    public class BankAccountTransfer {
        public static void main(String[] args) {
            Scanner sc = new Scanner(System.in);
            System.out.println("请输入登录的卡号:");
            String  ano  = sc.nextLine();
            System.out.println("请输入登录的密码:");
            String  apassword = sc.nextLine();
            Connection  conn = null;
            PreparedStatement ps = null;
            /* 定义两个转账的  PreparedStatement */
            PreparedStatement from = null;
            PreparedStatement to = null;
            ResultSet  rs = null;
            BankAccount  ba = null;
            conn = JdbcUtil2.getConnection();
            String  sql="select * from bank_account where ano=? and apassword=?";
            try {
                ps=conn.prepareStatement(sql);
                ps.setString(1, ano);
                ps.setString(2, apassword);
                rs = ps.executeQuery();
                if(rs.next()){
                    ba = new BankAccount(rs.getInt("id"),
                       rs.getString("ano"), rs.getString("aname"), rs.getString("apassword"),
                       rs.getString("amoney"));
                }
                if(ba!=null){
                    System.out.println("登录成功");
                    // 从当前账户中扣除输入的金额
                    System.out.println("请输入转账的金额:");
                    String  smoney=sc.nextLine();
                    double  money = Double.parseDouble(smoney);
                    sql="update  bank_account set amoney=amoney-? where ano=?";
                    // 禁止自动提交  
                    conn.setAutoCommit(false);
                    from = conn.prepareStatement(sql);
                    from.setDouble(1, money);
                    from.setString(2, ba.getAno());
                    int  fromf=from.executeUpdate();
                    // 提示用户输入转入的账号  和  账户名
                    System.out.println("请输入收款的账号:");
                    String  toano = sc.nextLine();
                    System.out.println("请输入收款人姓名:");
                    String  toaname= sc.nextLine();
                    sql="update  bank_account set amoney=amoney+? where ano=? and aname=?";
                    to=conn.prepareStatement(sql);
                    to.setDouble(1, money);
                    to.setString(2, toano);
                    to.setString(3, toaname);
                    int tof = to.executeUpdate();
                    if(fromf==1 && tof==1){
                        System.out.println("转账成功");
                        conn.commit(); //提交
                    }else{
                        System.out.println("转账失败");
                        conn.rollback(); //回滚
                    }
                }else{
                    System.out.println("登录失败");
                }
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                try {
                    conn.rollback();
                } catch (SQLException e1) {
                    e1.printStackTrace();
                }
                e.printStackTrace();
            }finally{
                JdbcUtil2.releaseResource(conn, ps, rs);
                JdbcUtil2.releaseResource(conn, from, null);
                JdbcUtil2.releaseResource(conn, to, null);
            }
        }
    }