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Question

我的代码有问题。在 MainFrame.java 中，我创建了一个新的 JDialog，它将 ResultSet 从 derby 数据库加载到 jTable。我已在数据库中插入 150000 行用于测试目的。将 ResultSet 中的值加载到 jTable(在 LoadTable() 方法中)会增加 java.exe 系统资源内存约 500 mb。 问题是在处理 JDialog 时，所使用的 500 MB 没有被释放。仅当在 MainFrame.java 中调用 system.exit() 时，它们才会被释放。

当我重新打开 JDialog 时，内存资源增加到 800mb。第三次重新打开 JDialog 将内存增加到 1 Gb，依此类推。

以下是使用的代码:
1)调用JDialog:

   private void jMenuItem1ActionPerformed(java.awt.event.ActionEvent evt)                                           
    {                                               
        try
        {
            Database.GetConnection().commit();
        }
        catch (SQLException ex)
        {
            Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);
            Log.GetLogger().log(Level.ALL, "jMenuItem1ActionPerformed() Method in MainFrame.Java, Database error!", ex);
            MessageBox.ShowMessage(this, ex.toString(), "ERROR", JOptionPane.ERROR_MESSAGE);
        }
        Insert ins = new Insert(this, true);
        ins.setVisible(true);
    }

2) 将值加载到 jTable 中:

    private void LoadTable() throws SQLException
    {

        Timestamp tstart = new Timestamp(new java.util.Date().getTime());

        //get all from database
        ResultSet rs;
        rs = Database.GetCutiiAll();

        Timestamp tstop1 = new Timestamp(new java.util.Date().getTime());

        //create a model for the table
        int len = Database.GetColoaneArr().length + 1;
        javax.swing.table.DefaultTableModel tableModel = new DefaultTableModel(0, len);
        //set table headers for columns
        String[] headers = new String[Database.GetColoaneArr().length + 1];
        headers[0] = "ID";
        System.arraycopy(Database.GetColoaneArr(), 0, headers, 1, headers.length - 1);
        tableModel.setColumnIdentifiers(headers);
        //set selection mode
        table1.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        //insert rows to table
        int rowNo = 0;
        while (rs.next())
        {
            //create object array with values for table columns
            int length = headers.length;
            Object[] data = new Object[length];
            for (int i = 0; i < length; i++)
            {
                //parse values where are foreign keys in the database
                Object val = rs.getObject(headers[i]);
                switch (headers[i])
                {
                    case "SERIE":
                    {
                        String[] temp = Database.GetSerii();
                        int index = (int) val;

                        data[i] = temp[index - 1];
                        break;
                    }
                    case "PROTECTIE_EX_1":
                    case "PROTECTIE_EX_2":
                    case "PROTECTIE_EX_3":
                    {
                        String[] temp = Database.GetProtectii();
                        int index = (int) val;

                        data[i] = temp[index - 1];
                        break;
                    }
                    case "TIP_MATERIAL":
                    {
                        String[] temp = Database.GetMateriale();
                        int index = (int) val;

                        data[i] = temp[index -1];
                        break;
                    }
                    default: 
                    {
                        data[i] = rs.getObject(headers[i]);
                        break;
                    } 
                }
            }
            tableModel.insertRow(rowNo, data);
            rowNo++;
        }
        //attach model to table
        table1.setModel(tableModel);
        //create listeners to update database when changing values        
        Timestamp tstop2 = new Timestamp(new java.util.Date().getTime());
        //show how long it took to load the database
        long s = tstop2.getTime() - tstart.getTime();
        jDurata.setText(String.valueOf(s) + " ms");
    }

3)处理JDialog:

private void jBtnIesireActionPerformed(java.awt.event.ActionEvent evt) {                                               
    // TODO add your handling code here:
    if (Database.GetCanSave())
    {
        int answer = MessageBox.ShowConfirmationMessage(this, "Salvati modificarile inainte de a iesi?", "OPTIUNE", JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);
        switch (answer)
        {
            case JOptionPane.CANCEL_OPTION: break;
            case JOptionPane.YES_OPTION: {
                try 
                {
                    Database.Save();
                }
                catch (SQLException ex)
                {
                    Logger.getLogger(Insert.class.getName()).log(Level.SEVERE, null, ex);
                    Log.GetLogger().log(Level.ALL, "Database.Save() Method in Insert.Java, Failed to update database.", ex);
                    MessageBox.ShowMessage(this, ex.toString(), "ERROR", JOptionPane.ERROR_MESSAGE);
                }
                break;
            }
            case JOptionPane.NO_OPTION: {
                try
                {
                    Database.RollbackAllSavepoints();
                }
                catch (SQLException ex)
                {
                    Logger.getLogger(Insert.class.getName()).log(Level.SEVERE, null, ex);
                    Log.GetLogger().log(Level.ALL, "Database.Undo() Method in Insert.Java, Failed to update database.", ex);
                    MessageBox.ShowMessage(this, ex.toString(), "ERROR", JOptionPane.ERROR_MESSAGE);
                }
                finally
                {
                    this.dispose(); 
                }
            }
            default: break;
        }
    }
    else
        this.dispose();
} 

提前致谢，抱歉，我无法在此处格式化代码。

Answer 1

将 150000 条记录加载到内存中是一个非常糟糕的主意。我相信你应该有一个分页，一次只加载一小块到内存中，比如 10 条记录。如果您将策略切换为使用分页，那么您的内存问题将得到解决。