1.学习视频：考试系统的第5节课 以及orm框架封装(1)
    2.学习内容：在今天的直播课上，复习jdbc基础知识点(jdbc六部曲)，详细讲解如何将连接数据库的代码冗余如何解决，
    通过封装一个新的方法，将变量通过参数的形式传到方法里，而将一样的部分放在方法体中，需要考虑到参数类型以及返回值的问题，因为对数据的不同操作需要使用的参数类型也不同，通过动态参数列表传递参数可以解决这些问题。**
    3.今天练习的代码：
    1）完成项目知识点 银行系统的存款、取款、转账和销户功能

    1. //观察者模式
    2.         //存款
    3.         //目标对象                      观察者
    4.         depositButton.addActionListener(new ActionListener() {
    5.             @Override
    6.             public void actionPerformed(ActionEvent e) {
    7.                 try {
    8.                     String value = JOptionPane.showInputDialog(BankFrame.this, "请输入存款金额");
    9.                     if (value != null && !"".equals(value)) {
    10.                         Float f = Float.parseFloat(value);
    11.                         if (f <= 0) {
    12.                             throw new NumberFormatException();
    13.                         }
    14.                         int count = service.deposit(bname, f);
    15.                         if (count == 1) {
    16.                             JOptionPane.showMessageDialog(BankFrame.this, "存款成功");
    17.                             balanceLabelCN.setText("账号余额:￥：" + service.inpuire(bname));
    18.                             balanceLabelEN.setText("Account Aalancd:￥：" + service.inpuire(bname));
    19.                         } else {
    20.                             JOptionPane.showMessageDialog(BankFrame.this, "抱歉，存款失败");
    21.                         }
    22.                     }
    23.                 }catch (NumberFormatException nef){
    24.                     JOptionPane.showMessageDialog(BankFrame.this, "抱歉，您输入的金额有误");
    25.                 }
    26.             }
    27.         });
    28.         //取款
    29.         withdrawalButton.addActionListener(new ActionListener() {
    30.             @Override
    31.             public void actionPerformed(ActionEvent e) {
    32.                 try {
    33.                     String value = JOptionPane.showInputDialog(BankFrame.this, "请输入取款金额");
    34.                     if (value != null && !"".equals(value)) {
    35.                         Float f = Float.parseFloat(value);
    36.                         if (f <= 0) {
    37.                             throw new NumberFormatException();
    38.                         }
    39.                         int count = service.withdrawal(bname, f);
    40.                         if (count == 1) {
    41.                             JOptionPane.showMessageDialog(BankFrame.this, "取款成功");
    42.                             balanceLabelCN.setText("账号余额:￥：" + service.inpuire(bname));
    43.                             balanceLabelEN.setText("Account Aalancd:￥：" + service.inpuire(bname));
    44.                         } else if(count==-1) {
    45.                             JOptionPane.showMessageDialog(BankFrame.this, "抱歉，余额不足");
    46.                         }else {
    47.                                 JOptionPane.showMessageDialog(BankFrame.this, "抱歉，取款失败");
    48.                             }
    49.                         }
    50.                 }catch (NumberFormatException nef){
    51.                     JOptionPane.showMessageDialog(BankFrame.this, "抱歉，您输入的金额有误");
    52.                 }
    53.             }
    54.         });
    55.         //转账
    56.         transferButton.addActionListener(new ActionListener() {
    57.             @Override
    58.             public void actionPerformed(ActionEvent e) {
    59.                 try {
    60.                     String inname = JOptionPane.showInputDialog(BankFrame.this, "请输入转账用户：");
    61.                     if (inname != null && !"".equals(inname) && service.isExist(inname)) {
    62.                         String value = JOptionPane.showInputDialog(BankFrame.this, "请输入转账金额：");
    63.                         if (value != null && !"".equals(value)) {
    64.                             Float money = Float.parseFloat(value);
    65.                             if (money <= 0) {
    66.                                 throw new NumberFormatException();
    67.                             }
    68.                             int count = service.transfer(bname, inname, money);
    69.                             if (count == 2) {
    70.                                 JOptionPane.showMessageDialog(BankFrame.this, "转账成功");
    71.                                 balanceLabelCN.setText("账号余额:￥：" + service.inpuire(bname));
    72.                                 balanceLabelEN.setText("Account Aalancd:￥：" + service.inpuire(bname));
    73.                             } else if (count == -1) {
    74.                                 JOptionPane.showMessageDialog(BankFrame.this, "抱歉，余额不足");
    75.                             } else {
    76.                                 JOptionPane.showMessageDialog(BankFrame.this, "抱歉，转账失败");
    77.                             }
    78.                         }
    79.                     }else {
    80.                         JOptionPane.showMessageDialog(BankFrame.this, "输入账号有误");
    81.                     }
    82.                 }catch (NumberFormatException nef){
    83.                     JOptionPane.showMessageDialog(BankFrame.this, "抱歉，您输入的金额有误");
    84.                 }
    85.             }
    86.         });
    87. //===============================================================================
    89. //设计一个方法 存款
    90.     public int deposit(String bname,Float bmoney){
    91.         Bank bank = bankDao.select(bname);
    92.         bank.setBmoney(bmoney+bank.getBmoney());
    93.         return bankDao.update(bank);
    94.     }
    95.     //设计一个方法 取款
    96.     public int withdrawal(String bname,Float withdrawalMoney){
    97.         Bank bank = bankDao.select(bname);
    98.         if(bank.getBmoney()>=withdrawalMoney) {
    99.             bank.setBmoney(bank.getBmoney() - withdrawalMoney);
    100.             return bankDao.update(bank);//1成功  0没有成功
    101.         }else {
    102.             return -1;//余额不足
    103.         }
    104.     }
    105.     //转账
    106.     public int transfer(String outName,String inName,Float Money){
    107.         Bank out = bankDao.select(outName);
    108.         Bank in = bankDao.select(inName);
    109.         if(out.getBmoney()>=Money){
    110.             out.setBmoney(out.getBmoney()-Money);
    111.             in.setBmoney(in.getBmoney()+Money);
    112.             return bankDao.update(out)+bankDao.update(in);//2成功
    113.         }else {
    114.             return -1;//余额不足
    115.         }
    116.     }

    2）对于连接数据库进行增、删、改方法去除冗余的练习

    1. package dao;
    3. import domain.Bank;
    5. import java.sql.Connection;
    6. import java.sql.DriverManager;
    7. import java.sql.PreparedStatement;
    9. public class BankDao {
    10.     private String className = "com.mysql.jdbc.Driver";
    11.     private String url = "jdbc:mysql://localhost:3306/bank?characterEncoding=UTF-8&useSSL=false";
    12.     private String user = "root";
    13.     private String password = "root";
    15.     //设计一个方法 可以执行任何一个表格的任何一条增删改
    16.     public void superUpdate(String sql,Object... obj){
    17.         try {
    18.             Class.forName(className);
    19.             Connection conn = DriverManager.getConnection(url,user,password);
    20.             PreparedStatement ps = conn.prepareStatement(sql);
    21.             for(int i=0;i<obj.length;i++) {
    22.                 ps.setObject(i+1,obj[i]);
    23.             }
    24.             ps.executeUpdate();
    25.             ps.close();
    26.             conn.close();
    27.         } catch (Exception e) {
    28.             e.printStackTrace();
    29.         }
    30.     }
    31. //=====================================================================
    32.     //新增
    33.     public void insert(String bname,String bpassword,Float bmoney){
    34.         String sql = "insert into bs values(?,?,?)";
    35.         this.superUpdate(sql,bname,bpassword,bmoney);
    36.     }
    37.     //删除
    38.     public void delect(String bname){
    39.         String sql = "delete from bs where bname = ?";
    40.         this.superUpdate(sql,bname);
    41.     }
    42.     //更新-->修改数据
    43.     public void update(Bank bank){
    44.         String sql = "update bs set bpassword = ? , bmoney = ? where bname = ?";
    45.         this.superUpdate(sql,bank.getBpassword(),bank.getBmoney(),bank.getBname());
    46.     }
    47. }

    封装了三个方法 update selectOne selectList
    增删改查—->参数采用了Object[]方式
    查询———->采用了策略模式
    问题:
    参数处理的可读性不好
    参数用户DAO使用的时候需要自己注意顺序
    返回值采用了DAO自己提供策略(类->内部类->匿名内部类)