我正在用java創建一個管理系統。Java。登錄不起作用
我有這個登錄表單。與數據庫的連接看起來很好，因爲它沒有給出錯誤。
但是，當我嘗試做嘗試{}和catch {}，它給出了一個錯誤。
我希望，如果任何人能幫助我。
它給出了這樣的總是：
趕上（例外）{ JOptionPane.showMessageDialog（NULL， 「登錄錯誤」， 「上登錄操作錯誤」，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
}
的數據庫連接類代碼：
公共類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;
}
}
}
的例外我得到的是這樣的：
運行：java.sql.SQLSyntaxErrorException：架構 'AAP' 根本不 org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException（未知 來源）在 org.apache.derby.impl.jdbc存在.Util.generateCsSQLException（未知來源） 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 來源）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 登錄$ 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（集裝箱。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（本機方法）。 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）
使用'ex.printStackTrace（）'，所以你可以看到實際的異常是什麼。 _「登錄操作出錯」_並不多說 –
'getDBConnection'相同 –
併發布例外 –