Java。登录不起作用

我正在用java创建一个管理系统。Java。登录不起作用

我有这个登录表单。与数据库的连接看起来很好，因为它没有给出错误。

但是，当我尝试做尝试{}和catch {}，它给出了一个错误。

我希望，如果任何人能帮助我。

它给出了这样的总是：

赶上（例外）{ JOptionPane.showMessageDialog（NULL， “登录错误”， “上登录操作错误”，JOptionPane.ERROR_MESSAGE）; }

public class Login extends javax.swing.JFrame { 


     private Connection con; 
     Dimension screen = Toolkit.getDefaultToolkit().getScreenSize(); 


public Login() { 
    super("System Login"); 
    initComponents(); 


    this.setResizable(false); 
    this.setLocation((screen.width - 500)/2, ((screen.height - 350)/2)); 
    this.setDefaultCloseOperation(EXIT_ON_CLOSE); 

    comcateg.addItem("Manager"); 
    comcateg.addItem("Clerk"); 

    ButtonListener listener = new ButtonListener(); 
    btlogin.addActionListener(listener); 
    btcancel.addActionListener(listener); 
    con = DBConnection.getDBConnection(); 
    if (con == null) { 
     JOptionPane.showMessageDialog(null, "Error on establishing database connection", "Error", JOptionPane.ERROR_MESSAGE); 
     this.dispose(); 
    } 
    } 

public void log(){ 

    String user = txtuser.getText(); 
    String pw = txtpw.getText(); 
    String cat = comcateg.getSelectedItem().toString(); 
    String SQL; 
    SQL = "SELECT * FROM AAP.USERS WHERE user_id='" + user + "' AND pword='" + pw +"' AND categ='" + cat +"'"; 

    **try{ 

     Statement stmt = con.createStatement(); 
     stmt.execute(SQL); 
     ResultSet rs = stmt.getResultSet(); 
     boolean recordfound = rs.next(); 
     if (recordfound) { 
      LoadMainWindow();     
      this.dispose(); 
     } else { 
      JOptionPane.showMessageDialog(null, "The system could not log you in.\n" + 
        " Please make sure your username and password are correct", "Login Failure", JOptionPane.INFORMATION_MESSAGE); 
      txtuser.setText(""); 
      txtpw.setText(""); 
      txtuser.requestFocus(); 
     } 
    } 
    catch (Exception ex) { 
     JOptionPane.showMessageDialog(null, "Error on login operation", "Login Error", JOptionPane.ERROR_MESSAGE); 
    } 


}** 
public void LoadMainWindow() { 
    if (comcateg.getSelectedItem().equals("Manager")) { 
     new MainWindow().LoginManager();    
    } else { 
     new MainWindow().LoginClerk(); 
    } 
    } 

private class ButtonListener implements ActionListener { 


    public void actionPerformed(ActionEvent e) { 
     if (e.getSource() == btlogin) { 
      if (txtuser.getText() == null || txtuser.getText().equals("")) { 
       JOptionPane.showMessageDialog(null, "Enter username", "Missing field", JOptionPane.DEFAULT_OPTION); 
       txtuser.requestFocus(); 
       return; 
      } 
      if (txtpw.getText() == null || txtpw.getText().equals("")) { 
       JOptionPane.showMessageDialog(null, "Enter password", "Missing field", JOptionPane.DEFAULT_OPTION); 
       txtpw.requestFocus(); 
       return; 
      } 
      log(); 
     } else if (e.getSource() == btcancel) { 
      System.exit(0); 
     }//if else closed 
    }//actionPerformed() closed 
} 

@SuppressWarnings("unchecked") 
// <editor-fold defaultstate="collapsed" desc="Generated Code">       
private void initComponents() { 

    jPanel1 = new javax.swing.JPanel(); 
    userid = new javax.swing.JLabel(); 
    pword = new javax.swing.JLabel(); 
    categ = new javax.swing.JLabel(); 
    txtuser = new javax.swing.JTextField(); 
    txtpw = new javax.swing.JTextField(); 
    comcateg = new javax.swing.JComboBox(); 
    btlogin = new javax.swing.JButton(); 
    btcancel = new javax.swing.JButton(); 

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

    userid.setText("User ID:"); 

    pword.setText("Password:"); 

    categ.setText("Category:"); 

    txtuser.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      txtuserActionPerformed(evt); 
     } 
    }); 

    txtpw.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      txtpwActionPerformed(evt); 
     } 
    }); 

    comcateg.setModel(new javax.swing.DefaultComboBoxModel(new String[] {})); 
    comcateg.setToolTipText(""); 
    comcateg.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      comcategActionPerformed(evt); 
     } 
    }); 

    btlogin.setText("Login"); 
    btlogin.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      btloginActionPerformed(evt); 
     } 
    }); 

    btcancel.setText("Cancel"); 
    btcancel.addActionListener(new java.awt.event.ActionListener() { 
     public void actionPerformed(java.awt.event.ActionEvent evt) { 
      btcancelActionPerformed(evt); 
     } 
    }); 

    org.jdesktop.layout.GroupLayout jPanel1Layout = new org.jdesktop.layout.GroupLayout(jPanel1); 
    jPanel1.setLayout(jPanel1Layout); 
    jPanel1Layout.setHorizontalGroup(
     jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING) 
     .add(jPanel1Layout.createSequentialGroup() 
      .add(40, 40, 40) 
      .add(jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING, false) 
       .add(jPanel1Layout.createSequentialGroup() 
        .add(btlogin) 
        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
        .add(btcancel)) 
       .add(jPanel1Layout.createSequentialGroup() 
        .add(categ) 
        .addPreferredGap(org.jdesktop.layout.LayoutStyle.UNRELATED) 
        .add(comcateg, 0, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)) 
       .add(jPanel1Layout.createSequentialGroup() 
        .add(pword) 
        .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED) 
        .add(txtpw)) 
       .add(jPanel1Layout.createSequentialGroup() 
        .add(userid) 
        .add(18, 18, 18) 
        .add(txtuser, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, 154, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE))) 
      .addContainerGap(64, Short.MAX_VALUE)) 
    ); 
    jPanel1Layout.setVerticalGroup(
     jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING) 
     .add(jPanel1Layout.createSequentialGroup() 
      .add(48, 48, 48) 
      .add(jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE) 
       .add(userid) 
       .add(txtuser, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)) 
      .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED) 
      .add(jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE) 
       .add(pword) 
       .add(txtpw, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)) 
      .addPreferredGap(org.jdesktop.layout.LayoutStyle.RELATED) 
      .add(jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE) 
       .add(categ) 
       .add(comcateg, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.PREFERRED_SIZE)) 
      .add(18, 18, 18) 
      .add(jPanel1Layout.createParallelGroup(org.jdesktop.layout.GroupLayout.BASELINE) 
       .add(btlogin) 
       .add(btcancel)) 
      .addContainerGap(48, Short.MAX_VALUE)) 
    ); 

    org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane()); 
    getContentPane().setLayout(layout); 
    layout.setHorizontalGroup(
     layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING) 
     .add(jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
    ); 
    layout.setVerticalGroup(
     layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING) 
     .add(org.jdesktop.layout.GroupLayout.TRAILING, jPanel1, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, org.jdesktop.layout.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) 
    ); 

    pack(); 
}// </editor-fold>       

private void txtuserActionPerformed(java.awt.event.ActionEvent evt) {           
    // TODO add your handling code here: 
}          

private void txtpwActionPerformed(java.awt.event.ActionEvent evt) {          
    // TODO add your handling code here: 
}          

private void btloginActionPerformed(java.awt.event.ActionEvent evt) {           
    // TODO add your handling code here: 
}          

private void btcancelActionPerformed(java.awt.event.ActionEvent evt) {           
    // TODO add your handling code here: 
}           

private void comcategActionPerformed(java.awt.event.ActionEvent evt) {           
    // TODO add your handling code here: 
}           

/** 
* @param args the command line arguments 
*/ 
public static void main(String args[]) { 
    /* Set the Nimbus look and feel */ 
    //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) "> 
    /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel. 
    * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
    */ 
    try { 
     for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) { 
      if ("Nimbus".equals(info.getName())) { 
       javax.swing.UIManager.setLookAndFeel(info.getClassName()); 
       break; 
      } 
     } 
    } catch (ClassNotFoundException ex) { 
     java.util.logging.Logger.getLogger(Login.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (InstantiationException ex) { 
     java.util.logging.Logger.getLogger(Login.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (IllegalAccessException ex) { 
     java.util.logging.Logger.getLogger(Login.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } catch (javax.swing.UnsupportedLookAndFeelException ex) { 
     java.util.logging.Logger.getLogger(Login.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); 
    } 
    //</editor-fold> 

    /* Create and display the form */ 
    java.awt.EventQueue.invokeLater(new Runnable() { 
     public void run() { 
      new Login().setVisible(true); 
     } 
    }); 
} 
// Variables declaration - do not modify      
private javax.swing.JButton btcancel; 
private javax.swing.JButton btlogin; 
private javax.swing.JLabel categ; 
private javax.swing.JComboBox comcateg; 
private javax.swing.JPanel jPanel1; 
private javax.swing.JLabel pword; 
private javax.swing.JTextField txtpw; 
private javax.swing.JTextField txtuser; 
private javax.swing.JLabel userid; 
// End of variables declaration

}

的数据库连接类代码：

公共类DBConnection的{

public static Connection getDBConnection() { 
    Connection connection; 
    try { 
     Class.forName("org.apache.derby.jdbc.ClientDriver"); 
     connection = DriverManager.getConnection("jdbc:derby:Ambulance;create=true"); 
     return connection; 
    } catch (Exception ex) { 
     return null; 
    } 
} 
}

的例外我得到的是这样的：

运行：java.sql.SQLSyntaxErrorException：架构 'AAP' 根本不 org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException（未知来源）在 org.apache.derby.impl.jdbc存在.Util.generateCsSQLException（未知来源）在 org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException（未知源）在 org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException（未知源）在 org.apache.derby.impl.jdbc.EmbedConnection.handleException（未知源）在 org.apache.derby.impl.jdbc.ConnectionChild.handleException（未知来源）at org.apache.derby.impl.jdbc.EmbedStatement.execute（Unknown Source）at org.apache.derby.impl.jdbc.EmbedStatement.execute（Unknown Source）at Login.log（Login.java： 56）在登录$ ButtonListener.actionPerformed（Login.java:99）在 javax.swing.AbstractButton.fireActionPerformed（AbstractButton.java:2018）在 javax.swing.AbstractButton中的$ Handler.actionPerformed（AbstractButton.java:2341 ）在 javax.swing.DefaultButtonModel.fireActionPerformed（DefaultButtonModel.java:402）在 javax.swing.DefaultButtonModel.setPressed（DefaultButtonModel.java:259）在 javax.swing.plaf.basic.BasicButtonLis tener.mouseReleased（BasicButtonListener.java:252） at java.awt.Component.processMouseEvent（Component.java:6505）at javax.swing.JComponent.processMouseEvent（JComponent.java:3321）at java.awt.Component。的processEvent（Component.java:6270）在 java.awt.Container.processEvent（Container.java:2229）在 java.awt.Component.dispatchEventImpl（Component.java:4861）在 java.awt.Container.dispatchEventImpl（ Container.java:2287）在 java.awt.Component.dispatchEvent（Component.java:4687）在 java.awt.LightweightDispatcher.retargetMouseEvent（集装箱。的java：4832）在 java.awt.LightweightDispatcher.processMouseEvent（Container.java:4492）在java.awt.LightweightDispatcher.dispatchEvent（Container.java:4422）在java.awt.Container.dispatchEventImpl（Container.java ：2273）at java.awt.Window.dispatchEventImpl（Window.java:2719）at java.awt.Component.dispatchEvent（Component.java:4687）at java.awt.EventQueue.dispatchEventImpl（EventQueue.java:729 ）at java.awt.EventQueue.access $ 200（EventQueue.java:103）at java.awt.EventQueue $ 3.run（EventQueue.java:688）at java.awt.EventQueue $ 3.run（EventQueue.java： 686）at java.security.AccessController.doPrivileged（Native Method）at java .security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76） at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:87） at java.awt.EventQueue $ 4.run（EventQueue.java:702）at java.awt.EventQueue中的$ 4.run在 java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76）在爪哇（EventQueue.java:700）在 java.security.AccessController.doPrivileged（本机方法）。 awt.EventQueue.dispatchEvent（EventQueue.java:699）在 java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:242）在 java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:161）在 java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:150）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:146）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:138）在java.awt.EventDispatchThread.run（EventDispatchThread.java:91）

来源

2014-02-15 Saad Ilamdin

使用'ex.printStackTrace（）'，所以你可以看到实际的异常是什么。 _“登录操作出错”_并不多说 –

'getDBConnection'相同 –

并发布例外 –

，我认为是没有得到正确执行查询，因为架构AAP不存在，你正在访问的表用户“SELECT * FROM AAP .USERS ...“，它在第41行stmt.execute（SQL）处得到异常;

因为它是在catch块。

来源

2015-03-13 13:20:04

在

SQL = "SELECT * FROM AAP.USERS WHERE user_id='" + user + "' AND pword='" + pw 
+"' AND categ='" + cat +"'";

你AAP表不存在，您需要确保您的查询之前已创建。

来源

2017-04-20 17:11:01

Java。登录不起作用

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