TableModel，在Java JFrame中导致重复的数据库信息

我在JFrame中设置了这个方法，当用户按下按钮来“加载文件”时调用;但是，当用户再次按下按钮时。。。他们会在第一张桌子下面放置另一张桌子，这样所有的信息都会被复制，并且超出我的“不可调整大小”的框架。TableModel，在Java JFrame中导致重复的数据库信息

无论用户按下按钮多少次，我怎样才能得到它只加载一个表？

JButton btnLoad = new JButton("Load File") 

private void GetAction() 
{ 
    ActionHandler handler = new ActionHandler(); 
    btnLoad.addActionListener(handler); 
} 

    private class ActionHandler implements ActionListener 
{  
    public void actionPerformed(ActionEvent evt) 
    { 
     String incmd = evt.getActionCommand(); 
     if (incmd.equals("Load File")) // If Load File button is pressed 
      DatabaseLoad(); 
     else if (incmd.equals("Exit")) // If Exit button is pressed 
      System.exit(0); 
    } 
} 
    private void DatabaseLoad() 
    { 
     try 
     { 
      // The driver allows you to query the database with Java 
      // forName dynamically loads the class for you   
      Class.forName("com.mysql.jdbc.Driver"); 

      // DriverManager is used to handle a set of JDBC drivers 
      // getConnection establishes a connection to the database 
      // You must also pass the userid and password for the database    
      String url = "jdbc:mysql://localhost:3306/charity"; 
      conn = DriverManager.getConnection (url,"root","password"); 

      // Statement objects executes a SQL query 
      // createStatement returns a Statement object    
      Statement sqlState = conn.createStatement(); 

      // This is the query I'm sending to the database 
      String selectStuff = "SELECT `name`, `charity`, `amount` FROM `charity`.`donations` ";     

      // A ResultSet contains a table of data representing the 
      // results of the query. It can not be changed and can 
      // only be read in one direction    
      rows = sqlState.executeQuery(selectStuff); 

      // Temporarily holds the row results    
      Object[] tempRow; 

      // next is used to iterate through the results of a query    
      while(rows.next()){ 

      // Gets the column values based on class type expected 
      tempRow = new Object[]{rows.getString(1), rows.getString(2), rows.getDouble(3) }; 

      // Adds the row of data to the end of the model    
      dTableModel.addRow(tempRow);     

     } 
      // Successfully loaded, message the user 
      message1.setText("<html><font color='red'>Database Info Loaded</font>"); 
      message2.setText(""); 
    } 
     catch (SQLException ex) 
     {    
      // String describing the error   
      System.out.println("SQLException: " + ex.getMessage()); 

      // Vendor specific error code    
      System.out.println("VendorError: " + ex.getErrorCode()); 
     } 
     catch (ClassNotFoundException e) 
     { 
      // Executes if the driver can't be found 
      System.out.println("Driver Cannot be found"); 
      e.printStackTrace(); 
     } 

     // Create a JTable using the custom DefaultTableModel  
     JTable table = new JTable(dTableModel); 

     // Increase the font size for the cells in the table   
     table.setFont(new Font("Serif", Font.PLAIN, 16)); 

     // Increase the size of the cells to allow for bigger fonts   
     table.setRowHeight(table.getRowHeight()+5); 

     // Allows the user to sort the data  
     table.setAutoCreateRowSorter(true); 

     // right justify amount column 
     TableColumn tc = table.getColumn("amount"); 
     RightTableCellRenderer rightRenderer = new RightTableCellRenderer(); 
     tc.setCellRenderer(rightRenderer);  

     // Disable auto resizing 
     table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF); 

     // Set the width for the columns   
     TableColumn col1 = table.getColumnModel().getColumn(0); 
     col1.setPreferredWidth(200); 

     TableColumn col2 = table.getColumnModel().getColumn(1); 
     col2.setPreferredWidth(275); 

     TableColumn col3 = table.getColumnModel().getColumn(2); 
     col3.setPreferredWidth(75);  

     // Put the table in a scrollpane and add scrollpane to the frame   
     JScrollPane scrollPane = new JScrollPane(table); 
     scrollPane.setPreferredSize(new Dimension(552, 400)); 
     this.add(scrollPane, BorderLayout.CENTER); 
    } 

    // To change justification to the right 
    class RightTableCellRenderer extends DefaultTableCellRenderer { 
      public RightTableCellRenderer() { 
      setHorizontalAlignment(JLabel.RIGHT); 
     }   
    }

来源

2013-03-15 Ray Wade

你可以发布显示你的'ActionListener'和'JButton'的代码吗？ – 2013-03-15 16:39:56

我已经添加了您询问的部分，但它们非常基本，并且不认为它们对表 – 2013-03-15 17:19:17

我怎样才能得到它只能装载一个表不管用户多少次按下按钮？

应该只在构建GUI组件时创建表和滚动窗格。然后，当你想改变数据，你只需改变现有表的模型：

table.setModel(updatedModel);

来源

2013-03-15 17:08:40 camickr

有任何影响，因此将jTable的东西移动到不同的方法中，然后根据是否希望显示表或不？ – 2013-03-15 17:21:06

按照我希望得到您的帮助的方式工作。。。谢谢 – 2013-03-15 18:29:29

TableModel，在Java JFrame中导致重复的数据库信息

回答

相关问题