删除或插入后更新 JTable

Question

我有一个 JTable，它由使用 ResultSet 的 Access DB 填充 &AbstractTableModel。我有一种方法可以正确地从数据库中删除记录，但无法刷新 table 模型的当前视图。我看过类似的帖子并尝试使用 fireTableRowsDeleted 和 fireTableDataChanged 但没有成功。我还注意到其他帖子提到了 DefaultTableModel 的使用，因为它有 add/remove 行方法，但我正在使用的代码来自我去年使用的 Java 教科书（教授从未达到这一点所以我试图自己学习）...

这是自定义 JFrame 的 class：

class AdministrationFrame extends JFrame
{
 //set variable for location of database
 private static final File DB_FILE = 
   new File("C:\Eclipse\EmpInOutBoard - TEMP.accdb"); 
 
 //database URL
 private static final String DB_URL = "jdbc:ucanaccess://" + DB_FILE.getAbsolutePath();
 
 //set default query to retrieve all users sorted by last name
 private static final String DEFAULT_QUERY = 
   "SELECT EmployeeNo, FirstName, LastName, DisplayName, GroupName, CompanyName "
    + "FROM Employees "
    + "WHERE DisabledState = false "
    + "ORDER BY LastName";
 
 //layout for window
 private final BorderLayout layout;
 
 //administration window
 private final JFrame adminFrame;
 
 private final JPanel tablePanel;
 private final JPanel tablePanel2;
 private final JPanel buttonPanel;
 
 //items for tablePanel
 private final JLabel filterLabel;
 private final JTextField filterTextField;
 private final JButton filterButton;
 
 //items for buttonPanel
 private final JButton updateButton;
 private final JButton deleteButton;
 
 private String employeeID;
 
 private Connection conn;
 
 private JTable resultTable;
 
 private static ResultSetTableModel tblModel;
 
 public AdministrationFrame()
 {
  layout = new BorderLayout(10, 10);
  setLayout(layout);
  
  //place GUI components on JFrame's content pane
  adminFrame = new JFrame("Employee Modification Panel");
  
  //set up JPanels
  tablePanel = new JPanel();
  tablePanel2 = new JPanel();
  
  String tablePanelTitle = "Employee Details";
  tablePanel.setBorder(BorderFactory.createTitledBorder(null, 
    tablePanelTitle, TitledBorder.CENTER, TitledBorder.TOP,
    new Font("Arial", Font.BOLD + Font.ITALIC, 22), Color.BLACK));
  
  tablePanel2.setLayout(new BoxLayout(tablePanel2, BoxLayout.Y_AXIS));
  
  buttonPanel = new JPanel();
  
  //set up items in each JPanel
  filterLabel = new JLabel("Filter:");
  filterLabel.setAlignmentX(LEFT_ALIGNMENT);
  filterTextField = new JTextField();
  filterTextField.setAlignmentX(LEFT_ALIGNMENT);
  filterButton = new JButton("Apply Filter");
  filterButton.setAlignmentX(LEFT_ALIGNMENT);
  
  updateButton = new JButton("Add/Update");
  deleteButton = new JButton("Delete");
  
  //create ResultSetTableModel and display database table
  try
  {
   //create TableModel for results of the default query
   tblModel = new ResultSetTableModel(DB_URL, DEFAULT_QUERY);
   
   //create JTable based on the tblModel
   resultTable = new JTable(tblModel)
   {
    @Override
    public Dimension getPreferredScrollableViewportSize()
    {
     return new Dimension(600, 250);
    }
   };
   
   resultTable.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);
   resultTable.getTableHeader().setResizingAllowed(false); //disable column resizing
   resultTable.getTableHeader().setReorderingAllowed(false); //disable column dragging
   resultTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); //sets table to only allow selection of single row
   resultTable.getSelectionModel().addListSelectionListener(new RowListener()); //register event handlers
   final JScrollPane tablePane = new JScrollPane(resultTable);
   
   //add items to JPanels
   tablePanel2.add(filterLabel);
   tablePanel2.add(Box.createRigidArea(new Dimension(0, 2)));
   tablePanel2.add(filterTextField);
   tablePanel2.add(Box.createRigidArea(new Dimension(0, 10)));
   tablePanel2.add(filterButton);
   
   tablePanel.add(tablePane);
   tablePanel.add(tablePanel2);
      
   buttonPanel.add(updateButton);
   buttonPanel.add(deleteButton);


   //add JPanels to frame
   adminFrame.add(tablePanel, BorderLayout.NORTH);
   adminFrame.add(buttonPanel, BorderLayout.SOUTH);   

   final TableRowSorter<TableModel> sorter = new TableRowSorter<TableModel>(tblModel);
   resultTable.setRowSorter(sorter);
   
   //create listener for filterButton
   filterButton.addActionListener(new ActionListener()
   {
    //pass filter text to Listener
    public void actionPerformed(ActionEvent e)
    {
     String text = filterTextField.getText();
     
     if (text.length() == 0)
      sorter.setRowFilter(null);
     else
     {
      try
      {
       //make filter case-insensitive
       sorter.setRowFilter(RowFilter.regexFilter("(?i)" + text));
      }
      catch (PatternSyntaxException pse)
      {
       JOptionPane.showMessageDialog(null, "Bad regex pattern",
         "Bad regex pattern", JOptionPane.ERROR_MESSAGE);
      }
     }
    }
   });
   
   deleteButton.addActionListener(new ActionListener()
   {
    @Override
    public void actionPerformed(ActionEvent e)
    {
     if(employeeID != null && !employeeID.isEmpty())
     {
      try
      {
       deleteFromTable(employeeID);
       JOptionPane.showMessageDialog(null, "User " + employeeID + " deleted from the table",
         "Successful Deletion", JOptionPane.PLAIN_MESSAGE);
       
       //tblModel.fireTableRowsDeleted(resultTable.getSelectedRow(), resultTable.getSelectedRow());

      } 
      catch (SQLException e1) 
      {
       e1.printStackTrace();
      }
     }
     else
     {
      JOptionPane.showMessageDialog(null, "No user selected. Cannot perform delete.",
        "ERROR", JOptionPane.ERROR_MESSAGE);
     }
    }
   });
   
   pack();
   
   //dispose of window when user quits application
   //(do not want to close application)
   adminFrame.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
   adminFrame.setSize(800, 400);
   adminFrame.setVisible(true);
   adminFrame.setLocationRelativeTo(null);
   adminFrame.setResizable(false);
   
   //ensure database is closed when user quits application
   adminFrame.addWindowListener(new WindowAdapter()
   {
    //disconnect from database and exit when window has closed
    public void windowClosed(WindowEvent event)
    {
     tblModel.disconnectFromDatabase();
     System.exit(0);
    }
   });
  }
  catch (SQLException sqlException)
  {
   JOptionPane.showMessageDialog(null, sqlException.getMessage(),
     "Database error", JOptionPane.ERROR_MESSAGE);
   tblModel.disconnectFromDatabase();
   System.exit(1); //terminate application
  }
 }
 
 private class RowListener implements ListSelectionListener
 {
  @Override
  public void valueChanged(ListSelectionEvent event)
  {
   if(!event.getValueIsAdjusting())
   {
    int row = resultTable.getSelectedRow();
    if(row == -1) //no row found
     JOptionPane.showMessageDialog(adminFrame, "Selected row not found in filtered set",
       null, JOptionPane.WARNING_MESSAGE);
    else
    {
     employeeID = resultTable.getValueAt(row, resultTable.getColumn("EmployeeNo").getModelIndex()).toString();
    }
   }
  }
 };

 //updates DB to delete selected user/record from the table
 public void deleteFromTable(String empID) throws SQLException
 {
  PreparedStatement prepStmnt = null;
  
  String deleteSQL = "DELETE "
       + "FROM Employees "
       + "WHERE EmployeeNo = ?";
  try
  {
   conn = DriverManager.getConnection(DB_URL);
   conn.setAutoCommit(false);
   
   prepStmnt = conn.prepareStatement(deleteSQL);
   prepStmnt.setString(1, empID);
   prepStmnt.executeUpdate();
   conn.commit();
  }
  catch (SQLException sqlExcep)
  {
   sqlExcep.printStackTrace();
   if(conn != null)
   {
    try
    {
     System.err.print("Rolling back transaction");
     conn.rollback();
    }
    catch (SQLException excep)
    {
     excep.printStackTrace();
    }
   }
   System.exit(1); //terminate application
  }
  finally //close the connection
  {
   if(prepStmnt != null)
    prepStmnt.close();
   
   conn.setAutoCommit(true);
   conn.close();
  }
 }
 
}//end class EmpInOutBoard

这里是 AbstractTableModel 的 class（根据我的教科书略作修改）：

class ResultSetTableModel extends AbstractTableModel
{
 private final Connection connection;
 private final Statement statement;
 private ResultSet resultSet;
 private ResultSetMetaData resultSetMetaData;
 private int numRowCount;

 //track DB connection status
 private boolean dbConnStatus = false;
 
 //constructor initializes rSet and obtains its
 //metadata object; also determines number of rows
 public ResultSetTableModel(String url, String query) throws SQLException
 {
  //connect to the database
  connection = DriverManager.getConnection(url);
  
  //create statement to query database
  statement = connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_UPDATABLE);
  
  //update database connection status
  dbConnStatus = true;
  
  //set query and execute it
  setQuery(query);
 }
 
 //get class that represents column type
 @SuppressWarnings({ "unchecked", "rawtypes" })
 public Class getColumnClass(int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine Java class of column
  try
  {
   String className = resultSetMetaData.getColumnClassName(column + 1);
   
   //return Class object that represents class Name
   return Class.forName(className);
  }
  catch (Exception e)
  {
   e.printStackTrace();
  }
  
  return Object.class; //if problems occur above, assume type Object
 }
 
 //remove row in the ResultSet
 public void removeRow(int row)
 {
//  try
//  {
//   resultSet.absolute(row);
//   resultSet.deleteRow();
//  }
//  catch (SQLException e)
//  {
//   e.printStackTrace();
//  }
//  fireTableRowsDeleted(row, row);
 }
 
 //get the number of columns in the ResultSet
 public int getColumnCount() throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine number of columns
  try
  {
   return resultSetMetaData.getColumnCount();
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return 0; //if problem occur above, return 0 for number of columns
 }
 
 //get name of a particular column in ResultSet
 public String getColumnName(int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //determine column name
  try
  {
   return resultSetMetaData.getColumnName(column + 1);
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return ""; //if problems occur above, return empty string for column name 
 }
 
 //return number of rows in ResultSet
 public int getRowCount() throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  return numRowCount; 
 }
 
 //obtain value in particular row and column
 public Object getValueAt(int row, int column) throws IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //obtain a value at specified ResultSet row and column
  try
  {
   resultSet.absolute(row + 1);
   return resultSet.getObject(column + 1);
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  
  return ""; //if problems occur above, return empty string object  
 }
 
 //set new database query string
 public void setQuery(String query) throws SQLException, IllegalStateException
 {
  //ensure database connection is available
  if(!dbConnStatus)
   throw new IllegalStateException("No connection to the Database");
  
  //specify query and execute it
  resultSet = statement.executeQuery(query);
  
  //obtain metadata for ResultSet
  resultSetMetaData = resultSet.getMetaData();
  
  //determine number of rows in ResultSet
  resultSet.last(); //move to last row
  numRowCount = resultSet.getRow(); //get row number
  
  //notify JTable that model has changed
  fireTableStructureChanged();
 }
 
 //close Statement and Connection
 public void disconnectFromDatabase()
 {
  //ensure database connection is available
  if(dbConnStatus);
  
  //determine number of columns
  try
  {
   resultSet.close();
   statement.close();
   connection.close();
  }
  catch (SQLException sqlException)
  {
   sqlException.printStackTrace();
  }
  finally
  {
   dbConnStatus = false;
  }
  
 }
} //end class ResultSetTableModel

如您所见，我尝试在第二个 class 中添加一个 removeRow 方法，但最终出现错误：attempt to assign to non-updatable column。我缺少什么来刷新我的 table 模型？如果这是 easier/simpler，我愿意将其更改为使用 DefaultTableModel 及其内置方法。谢谢

Answer 1

我没有使用直接行索引，因为如果用户按任何一列对数据进行排序，这可能会改变。我觉得因为 employeeID 是唯一的，所以匹配它会更好：

//remove row in the ResultSet
 public void removeRow(String empID)
 {
  int rsRow = 0;
  try
  {
   //set cursor to beginning of data set (before first row)
   if(!resultSet.isBeforeFirst())
    resultSet.beforeFirst();
   
   //iterate through resultSet to find matching record with
   //correct employee ID. once found delete row
   while(resultSet.next())
   {
    if(resultSet.getString("EmployeeNo") == empID)
    {
     rsRow = resultSet.getRow();
     
     resultSet.deleteRow();
     System.out.println("User: " + empID + " was deleted from row: " + rsRow);
     break;
    }
   }
   
   resultSet.last();
   numRowCount = resultSet.getRow();
   
   fireTableRowsDeleted(rsRow, rsRow);

//   resultSet.absolute(rsRow);
//   resultSet.deleteRow();
  }
  catch (SQLException e)
  {
   e.printStackTrace();
  }
 }

当然，现在 JTable 中的数据正在消失，我不明白。

删除或插入后更新 JTable

Update JTable after delete or insert

java

swing

jtable

abstracttablemodel