使用jdbc odbc連接java到ms訪問數據庫，java用戶登錄系統

Question

我有一個連接java到mc訪問來檢查用戶身份驗證的問題，當我運行這個程序時它不給我任何錯誤消息（我推測連接沒有問題），但它也不檢查帳號和密碼是否有效。其他方法如退出，存款和getBalance工作正常。
任何幫助或提示將不勝感激。

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 

class Logic 
{ 
    private enum State { ACCOUNT_NO, PASSWORD, PROCESSING }; 
    private State state = State.ACCOUNT_NO; 
    private long number; 
    private long acNumber = 0; 
    private long acPIN = 0; 
    private char op = ' '; 
    private Bank bank = new Bank(); 

    private JTextArea display1, display2; 


    public Logic(JTextArea area1, JTextArea area2) 
    { 
    display1 = area1; display2 = area2; 
    display2.setText("Welcome: Enter your account number"); 
    } 

    public void process(String button) 
    { 
    String info = null; 

    if (button.length() == 1) 
    { 
     char c = button.charAt(0); 
     if (c >= '0' && c <= '9')    // Digit 
     { 
     number = number * 10 + c-'0';   // Build number 
     display1.setText("" + number); 
     } 
     return; 
    } 

    if (button.equals("CLR")) 
    { 
     number = 0; 
     display1.setText("" + number); 
    } 

    if (button.equals("Ent")) 
    { 
     switch (state) 
     { 
     case ACCOUNT_NO: 
      bank.setAcNumber(number); 
      number = 0; 
      state = State.PASSWORD; 
      display1.setText(""); 
      display2.setText("Now enter your password"); 
      break; 
     case PASSWORD: 
      bank.setAcPasswd(number); 
      number = 0; 
      display1.setText(""); 
      if (bank.checkValid()) 
      { 
      state = State.PROCESSING; 
      display2.setText("Now enter transaction"); 
      } else { 
      state = State.ACCOUNT_NO; 
      display2.setText("Invalid: Start again"); 
      } 
      break; 
     default : 
     } 
     return; 
    } 

    if (state != State.PROCESSING) 
    { 
     state = State.ACCOUNT_NO; 
     display2.setText("But you are not loged in\n" ); 
     display2.append("Welcome: Enter your account number"); 
     return; 
    } 

    if (button.equals("W/D"))    // Clear Result 
    { 
     display1.setText(""); 
     if (bank.withdraw(number)) 
     { 
     display2.setText("Withdrawn: " + number); 
     } else { 
     display2.setText("You do not have surficient funds"); 
     } 
     number = 0; 
     return; 
    } 

    if (button.equals("Bal"))    // Clear Result 
    { 
     number = 0; 
     display2.setText("Your balance is: " + bank.getBalance()); 
     return; 
    } 

    if (button.equals("Dep"))    // Clear Result 
    { 
     bank.deposit(number); 
     display1.setText(""); 
     display2.setText("Deposited: " + number); 
     number = 0; 
     return; 
    } 

    if (button.equals("Fin"))    // Clear Result 
    { 
     state = State.ACCOUNT_NO; 
     number = 0; 
     display2.setText("Welcome: Enter your account number"); 
     return; 
    } 

    return; 
    } 

    public long getResult() 
    { 
    return number; 
    } 

    public long getNumber() 
    { 
    return number; 
    } 
} 

銀行類。

import java.sql.*; 

class Bank 
{ 
    long AcNumber = 0; 
    long AcPasswd = 0; 
    long balance = 0; 
    long deposit = 0; 
    long withdraw = 0; 
    long amount = 0; 
    Connection con; 
    Statement st; 
    ResultSet rs; 


    public void connect() 
    { 
    try 
    { 
    String driver = "sun.jdbc.odbc.JdbcOdbcDriver"; 
    Class.forName(driver); 
    String db = "jdbc:odbc:db3"; 
    con = DriverManager.getConnection(db); 
    st = con.createStatement(); 
    } 

    catch (Exception ex) 
    { 
     System.err.println("Can not load JDBC/ODBC driver."); 
     System.exit(-1); 
    } 

    } 

    public void setAcNumber(long accNumber) 
    { 
     AcNumber = accNumber; 
    } 

    public void setAcPasswd(long accNumber) 
    { 
     AcPasswd = accNumber; 
    } 

    public boolean checkValid() 
    {  
     try { 
      String sql = "select user,pass from Table1 where user='"+AcNumber+"'and pass='"+AcPasswd+"'"; 
      rs = st.executeQuery(sql); 

      int count = 0; 
      while(rs.next()) 
      { 
       count = count + 1; 
      } 
      if(count == 1) 
      { 
       System.out.println("User Found, Now enter transaction"); 

      } 
      else 
      { 
       System.out.println("user not found"); 

      } 

     } 

      catch (Exception ex) 
      { 

      } 

     return true; 

    } 

    public boolean withdraw(long amount) 
    {   
     balance = balance - amount;  
     System.out.println("Bank: Withdrawm " + amount); 
     return true; 
    } 

    public void deposit(long amount) 
    {  
     balance = balance + amount;    
     System.out.println("Bank: deposit " + amount); 
     return; 
    } 

    public long getBalance() { 

     System.out.println("Bank: Balance: "+ balance); 
     return balance; 
    } 




} 

Answer 1

你可能是因爲你的時候，你趕上checkValid異常奈何沒有錯誤消息。在您的catch塊中添加ex.printStackTrace()以獲取有關正在發生的更多信息。