java+mybatis实现一个简单的银行系统，实现存取款与账户查询

先创建数据库和表，使用的是MySQL数据库。

create database mybatis;
use mybatis;
CREATE TABLE `accountdo` (
  `id` varchar(255) NOT NULL COMMENT '账户',
  `name` varchar(255) DEFAULT NULL COMMENT '用户姓名',
  `sex` varchar(255) DEFAULT NULL COMMENT '性别',
  `tele` varchar(255) DEFAULT NULL COMMENT '电话',
  `address` varchar(255) DEFAULT NULL COMMENT '住址',
  `balance` double DEFAULT NULL COMMENT '账户余额',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

新建一个Java项目，项目下新建一个lib文件夹，放入mysql-connector-java和mybatis的jar包，build path一下。

src目录下创建一个conf.xml和一个db.properties，

db.properties的内容如下：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis
name=root
password=root

password填写自己的密码。

编写一个mybatis工具类，代码如下：

package utils;

import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtil {

    /**
     * 获取SqlSessionFactory
     * @return SqlSessionFactory
     */
    public static SqlSessionFactory getSqlSessionFactory() {
        String resource = "conf.xml";
        InputStream is = MyBatisUtil.class.getClassLoader().getResourceAsStream(resource);
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        return factory;
    }

    /**
     * 获取SqlSession
     * @return SqlSession
     */
    public static SqlSession getSqlSession() {
        return getSqlSessionFactory().openSession();
    }

    /**
     * 获取SqlSession
     * @param isAutoCommit
     *         true 表示创建的SqlSession对象在执行完SQL之后会自动提交事务
     *         false 表示创建的SqlSession对象在执行完SQL之后不会自动提交事务，这时就需要我们手动调用sqlSession.commit()提交事务
     * @return SqlSession
     */
    public static SqlSession getSqlSession(boolean isAutoCommit) {
        return getSqlSessionFactory().openSession(isAutoCommit);
    }
}

编写账户实体类，将setId方法改为private，代码如下：

package bank.d;

/**
 * 账户实体类
 *
 * @author xmj
 *
 */
public class AccountDO {

    private String id;// 账户的号码
    private String name;// 账户姓名
    private String sex;// 性别
    private String tele;// 电话
    private String address;// 地址
    private double balance = 0;// 账户的余额，默认为0

    public String getId() {
        return id;
    }

    @SuppressWarnings("unused")
    private void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getTele() {
        return tele;
    }

    public void setTele(String tele) {
        this.tele = tele;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public double getBalance() {
        return balance;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    @Override
    public String toString() {
        return "\n账号：" + id + " \n姓名：" + name + "\n余额：" + balance;
    }

}

定义sql映射的接口，代码如下：

package bank.i;

import java.util.List;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import bank.d.AccountDO;

public interface IAccountMapper {

    // 使用@Insert注解指明add方法要执行的SQL
    @Insert("insert into AccountDO(id, name,sex,tele,address,balance) values(concat('BANK',DATE_FORMAT(now(),'%Y%m%d%H%i%s'),floor(1000+rand()*8999)), #{name}, #{sex}, #{tele}, #{address}, #{balance})")
    public int add(AccountDO user);

    // 使用@Delete注解指明deleteById方法要执行的SQL
    @Delete("delete from AccountDO where id=#{id}")
    public int deleteById(String id);

    // 使用@Update注解指明update方法要执行的SQL
    @Update("update AccountDO set name=#{name},sex=#{sex} ,tele=#{tele},address=#{address},balance=#{balance} where id=#{id}")
    public int update(AccountDO user);

    // 使用@Select注解指明getById方法要执行的SQL
    @Select("select * from AccountDO where id=#{id}")
    public AccountDO getById(String id);

    // 使用@Select注解指明getAll方法要执行的SQL
    @Select("select * from AccountDO")
    public List<AccountDO> getAll();

}

在conf.xml文件中注册这个映射接口，代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

    <!-- 引用db.properties配置文件 -->
    <properties resource="db.properties" />

    <!-- development : 开发模式 work : 工作模式 -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息 -->
            <dataSource type="POOLED">
                <property name="driver" value="${driver}" />
                <property name="url" value="${url}" />
                <property name="username" value="${name}" />
                <property name="password" value="${password}" />
            </dataSource>
        </environment>
    </environments>

    <mappers>

        <!-- 注册IAccountMapper映射接口 -->
        <mapper class="bank.i.IAccountMapper" />

    </mappers>

</configuration>

编写一个实现类，封装上面的映射接口里的方法，代码如下：

package bank.s;

import java.util.List;
import org.apache.ibatis.session.SqlSession;
import bank.d.AccountDO;
import bank.i.IAccountMapper;
import utils.MyBatisUtil;

public class AccountMapperImpl {

    /**
     * 判断字符串是否为空
     *
     * @param str
     * @return
     */
    public static boolean isEmpty(String str) {
        if (str == null || "".equals(str))
            return true;
        return false;
    }

    /**
     * 添加用户
     *
     * @param aggdo
     */
    public static void add(AccountDO aggdo) {
        if (aggdo == null)
            return;
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        IAccountMapper mapper = sqlSession.getMapper(IAccountMapper.class);
        int add = mapper.add(aggdo);
        sqlSession.close();
        System.out.println("有【" + add + "】条数据发生了改变");
    }

    /**
     * 修改
     *
     * @param aggdo
     */
    public static void update(AccountDO aggdo) {
        if (aggdo == null)
            return;
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        IAccountMapper mapper = sqlSession.getMapper(IAccountMapper.class);
        @SuppressWarnings("unused")
        int add = mapper.update(aggdo);
        // System.out.println("有【" + add + "】条数据发生了改变");
        sqlSession.close();
    }

    /**
     * 修改用户余额
     *
     * @param balance
     * @param id
     */
    public static void updateBalance(double balance, String id) {
        if (isEmpty(id))
            return;
        AccountDO user = getById(id);
        if (user == null) {
            System.out.println("无法通过【" + id + "】查到该用户信息");
            return;
        }
        user.setBalance(balance);
        SqlSession sqlSession = MyBatisUtil.getSqlSession(true);
        IAccountMapper mapper = sqlSession.getMapper(IAccountMapper.class);
        @SuppressWarnings("unused")
        int add = mapper.update(user);
        sqlSession.close();
        // System.out.println("有【" + add + "】条数据发生了改变");
    }

    /**
     * 通过账号查询用户信息
     *
     * @param id
     * @return
     */
    public static AccountDO getById(String id) {
        if (isEmpty(id))
            return null;
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        IAccountMapper mapper = sqlSession.getMapper(IAccountMapper.class);
        AccountDO lstUsers = mapper.getById(id);
        sqlSession.close();
        return lstUsers;
    }

    /**
     * 获取所有用户信息
     *
     * @return
     */
    public static List<AccountDO> getAll() {
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        IAccountMapper mapper = sqlSession.getMapper(IAccountMapper.class);
        List<AccountDO> lstUsers = mapper.getAll();
        sqlSession.close();
        return lstUsers;
    }

}

编写银行系统类，实现对账户的查询和存取款操作，代码如下：

package bank.bp;

import java.util.Scanner;
import bank.d.AccountDO;
import bank.s.AccountMapperImpl;

/**
 * 银行系统
 *
 * @author xmj
 *
 */
public class BankSystem {

    private AccountDO user;// 当前账户
    private double balance;// 余额

    /**
     * 银行操作系统。原存取款都对数据库的数据进行修改，现改成退出系统时才对数据库进行修改
     */
    public void system(String id) {
        this.user = AccountMapperImpl.getById(id);
        if (user == null) {
            System.out.println("无【" + id + "】此账户");
            return;
        }
        this.balance = user.getBalance();
        double unchang = balance;// 用户刚登陆系统时账户的余额，用来与操作后的balance比较，看余额是否发生改变
        System.out.println("------银行账户操作系统-------- ");
        System.out.println("----------1取款操作------------");
        System.out.println("----------2存款操作------------");
        System.out.println("----------3账户信息------------");
        System.out.println("----------4退出系统------------");
        boolean go_on = true;
        while (go_on) {
            @SuppressWarnings("resource")
            Scanner num = new Scanner(System.in);
            System.out.println("请输入您的选择：");
            int choice = num.nextInt();
            switch (choice) {
            case 1:
                System.out.println("-----正在进行【取款】操作------");
                this.withDrawal();
                break;
            case 2:
                System.out.println("-----正在进行【存款】操作------");
                this.deposit();
                break;
            case 3:
                System.out.println("-----账户信息------");
                this.info();
                break;
            case 4:
                if (unchang != balance)
                    AccountMapperImpl.updateBalance(balance, user.getId());
                System.out.println("------退出系统，欢迎下次光临------");
                go_on = false;
                break;
            default:
                System.out.println("您的选择有误！");
                break;
            }
        }
    }

    /**
     * 账户信息
     */
    private void info() {
        System.out.println("账号：" + user.getId() + "\n姓名：" + user.getName() + "\n余额：" + this.balance);
    }

    /**
     * 存款
     */
    private void deposit() {
        @SuppressWarnings("resource")
        Scanner balance1 = new Scanner(System.in);
        System.out.println("请输入您要存入的金额：");
        double money = balance1.nextDouble();
        balance = balance + money;
//        AccountMapperImpl.updateBalance(balance, user.getId());
        System.out.println("余额：" + balance);
    }

    /**
     * 取款
     */
    private void withDrawal() {
        @SuppressWarnings("resource")
        Scanner balance1 = new Scanner(System.in);
        System.out.println("请输入您要提取的金额：");
        double money = balance1.nextDouble();
        if (money > balance)
            System.out.println("您的余额不足");
        else {
            balance = (balance - money);
//            AccountMapperImpl.updateBalance(balance, user.getId());
        }
        System.out.println("余额：" + balance);
    }

}

编写测试类，代码如下：

package bank;

import bank.bp.BankSystem;
import bank.d.AccountDO;
import bank.s.AccountMapperImpl;

public class BankTest {

    public static void main(String[] args) {
        BankSystem s = new BankSystem();
        s.system("BANK202103151039575919");
//        add();
    }

    public static void add() {
        AccountDO a = new AccountDO();
        a.setName("小马驹");
        a.setSex("男");
        a.setTele("12345678901");
        a.setAddress("武汉市");
        AccountMapperImpl.add(a);
    }

}

整个项目的结构如图：

第一次写博客。。。