JTabbedPane 和 JScrollBar 联合使用

需求：实现一个JTabbed， 当下拉到Tabbed的底部时，自动加载下一次的数据。

下面是具体代码：

 import java.awt.*;
 import javax.swing.table.DefaultTableModel;
 import javax.swing.*;
 import javax.swing.event.ChangeEvent;
 import java.awt.event.*;

 public class JTabbedPaneExample extends JFrame implements AdjustmentListener
 {
     private GridBagLayout gridBagLayout = new GridBagLayout();
     private JSplitPane splitPane = new JSplitPane();
     private JPanel timePanel = new JPanel();

     private GridBagLayout gridBagLayoutForTime = new GridBagLayout();
     private JButton btnSearch = new JButton();
     private HistoryStatisticsTableModel historyStatisticsTableModel = new HistoryStatisticsTableModel();
     private JTable searchTable = new JTable(historyStatisticsTableModel);
     private JScrollPane searchScrollPane = new JScrollPane(searchTable);
     private JScrollBar scrollBarForVertical = new JScrollBar(JScrollBar.VERTICAL, 10, 10, 0, 100);
     private JScrollBar scrollBarForHorizontal = new JScrollBar(JScrollBar.HORIZONTAL, 10, 10, 0, 100);
     private int intPageNum = 1;

     public JTabbedPaneExample()
     {
         jbInit();
     }

     private void jbInit()
     {
         this.setLayout(gridBagLayout);
         searchTable.setEnabled(false);
         splitPane.setLastDividerLocation(-1);
         splitPane.setDividerLocation(150);
         this.add(splitPane,   new GridBagConstraints(0, 0, 1, 1, 1.0, 1.0
                 ,GridBagConstraints.NORTHWEST, GridBagConstraints.BOTH, new Insets(5, 5, 5, 5), 0, 0));

         timePanel.setLayout(gridBagLayoutForTime);
         splitPane.add(timePanel, JSplitPane.RIGHT);

         btnSearch.setText("Search");
         btnSearch.addActionListener(new java.awt.event.ActionListener()
         {
             public void actionPerformed(ActionEvent e)
             {
                 searchBtn_actionPerformed(e);
             }
         });

         timePanel.add(btnSearch, new GridBagConstraints(0, 2, 1, 1, 1.0, 1.0
                       ,GridBagConstraints.NORTHWEST, GridBagConstraints.NONE, new Insets(0, 50, 0, 0), 0, 0));
         timePanel.add(searchScrollPane, new GridBagConstraints(0, 3, 5, 1, 1.0, 1.0
                       ,GridBagConstraints.NORTHWEST, GridBagConstraints.BOTH, new Insets(0, 50, 50, 50), 0, 0));
         scrollBarForVertical.setUnitIncrement(1);
         scrollBarForVertical.setBlockIncrement(10);
         scrollBarForVertical.setMaximum(90);
         scrollBarForVertical.addAdjustmentListener(this);
         searchScrollPane.setVerticalScrollBar(scrollBarForVertical);
         searchScrollPane.setHorizontalScrollBar(scrollBarForHorizontal);
     }

      public void adjustmentValueChanged(AdjustmentEvent e)
      {
          boolean isChange = false;
          System.out.println("XXXXX bar Max : " + scrollBarForVertical.getMaximum());
          System.out.println("XXXX bar Max Size : " + scrollBarForVertical.getMaximumSize());
          System.out.println("XXXX bar pre size : " + scrollBarForVertical.getPreferredSize());
          System.out.println("XXXX pane Max size : " + searchScrollPane.getMaximumSize());
          System.out.println("XXXX pane size : " + searchScrollPane.getSize());
          System.out.println("XXXX pane getHeight size : " + searchScrollPane.getHeight());
          System.out.println("XXXX pane pre size : " + searchScrollPane.getPreferredSize());
          System.out.println("XXXX intPageNum : " + intPageNum);

          if ((JScrollBar) e.getSource() == scrollBarForVertical)
          {
              long currentValue = e.getValue();
              long diff = scrollBarForVertical.getMaximum() - searchScrollPane.getHeight();
              System.out.println("XXXX currentValue = " + currentValue);
              System.out.println("XXXX diff = " + diff);
              if(currentValue >= diff && 0 != currentValue) //下拉到table底部，自动加载下一次数据功能
              {
                  //System.out.println("XXXX scrollBarForVertical currentSize : " + currentSize);
                  System.out.println("XXXX Yes");
                  test();
                  intPageNum = intPageNum + 1;
                  isChange = true;
              }

              if(isChange)
              {
                 // scrollBarForVertical.setValue(0);
              }
          }
      }

     public static void main(String[] args)
     {
         JTabbedPaneExample test = new JTabbedPaneExample();
         test.setVisible(true);
     }

     private void test()
     {
         String[] aStrCategoryName = new String[500];
         String[] aStringCounterName = new String[500];
         String[] aStrStartTime = new String[500];
         String[] aStopTime = new String[500];
         String[] aStrValue = new String[500];
         int i = 0;
         for(; i < 499; i++)
         {
             aStrCategoryName[i] = i + "";
             aStringCounterName[i] = i + "";
             aStrStartTime[i] = i + "";
             aStopTime[i] = i + "";
             aStrValue[i] = i + "";
         }

         //historyStatisticsTableModel.createTable(aStrCategoryName, aStringCounterName, aStrStartTime, aStopTime, aStrValue);
         historyStatisticsTableModel.createTable(aStrCategoryName, aStringCounterName, aStrStartTime, aStopTime, aStrValue);
         //historyStatisticsTableModel.addRow();

     }

     private void searchBtn_actionPerformed(ActionEvent e)
     {
         test();
     }

     public class Parameter
     {
         public Parameter(String strCategoryName, String strCounterName, String strStartTime, String strStopTime, String strValue)
         {
             this.strCategoryName = strCategoryName;
             this.strCounterName = strCounterName;
             this.strStartTime = strStartTime;
             this.strStopTime = strStopTime;
             this.strValue = strValue;
         }

         public String strCategoryName;
         public String strCounterName;
         public String strStartTime;
         public String strStopTime;
         public String strValue;
     }

     private class HistoryStatisticsTableModel  extends DefaultTableModel
     {
         private String[] COLUMN_NAMES = {"Category Name", "Counter Name", "Start Time", "Stop Time", "Value"};
         public Parameter[] myparameters = new Parameter[0];

         public HistoryStatisticsTableModel()
         {
             super();
             super.setColumnIdentifiers(COLUMN_NAMES);

             super.setRowCount(0);
         }

         public int getColumnCount()
         {
             return COLUMN_NAMES.length;
         }

 /*
         public int getRowCount()
         {
             return myparameters.length;
         }
 */

         public void setRowCount(int rowCount)
         {
         }

         public String getColumnName(int col)
         {
             return COLUMN_NAMES[col];
         }

         public void addRow(String strCategoryName, String strCounterName, String strStartTime, String strStopTime, String strValue)
         {
             Object[] rowData = new Object[COLUMN_NAMES.length];
             for (int i = 0; i < COLUMN_NAMES.length; i++)
             {
                 switch(i)
                 {
                     //Category Name
                     case 0:
                         rowData[i] = strCategoryName;
                         break;
                     //Counter Name
                     case 1:
                         rowData[i] = strCounterName;
                         break;
                     //Start Time
                     case 2:
                         rowData[i] = strStartTime;
                         break;
                     //Stop Time
                     case 3:
                         rowData[i] = strStopTime;
                         break;
                     //Value
                     case 4:
                         rowData[i] = strValue;
                         break;
                     default:
                         rowData[i] = "";
                 }
             }

             super.addRow(rowData);
         }
        /*
         public Object getValueAt(int row, int col)
         {
             if (0 == col)
             {
                 return myparameters[row].date;
             }
             else if (1 == col)
             {
                 return myparameters[row].usage;
             }
             else if (2 == col)
             {
                 return myparameters[row].ratio;
             }
             else
             {
                 return null;
             }
         }
         */   

 /*
         public void createTable(Document response)
         {
             NodeList list = response.getElementsByTagName("Parameter");
             if (list.getLength() > 0)
             {
                 Parameter[] aParameters = new Parameter[list.getLength()];
                 Element eparameter;
                 int acounter = 0;
                 for (int i = 0; i < list.getLength(); i++)
                 {
                     eparameter = (Element)list.item(i);
                     String aStrCategoryName = getElementValue(eparameter.getElementsByTagName("Category Name"));
                     String aStrCounterName = getElementValue(eparameter.getElementsByTagName("Counter Name"));
                     String aStrStartTime = getElementValue(eparameter.getElementsByTagName("Start Time"));
                     String aStrStopTime = getElementValue(eparameter.getElementsByTagName("Stop Time"));
                     String aStrValue = getElementValue(eparameter.getElementsByTagName("Value"));
                     aParameters[i] = new Parameter(aStrCategoryName, aStrCounterName, aStrStartTime, aStrStopTime, aStrValue);
                 }
                 myparameters = aParameters;
             }
             else
             {
                 myparameters = new Parameter[0];
             }

             fireTableDataChanged();
         }
 */
         // Wirte for test
         public void createTable(String[] strCategoryName, String[] strCounterName, String[] strStartTime, String[] strStopTime, String[] strValue)
         {
             int intCounter = strCategoryName.length;

             for(int i = 0; i < intCounter; i++)
             {
                 addRow(strCategoryName[i], strCounterName[i], strStartTime[i], strStopTime[i], strValue[i]);
             }

             fireTableDataChanged();
         }
     }
 }

由于只是一个小Demo， 所以没有怎么整理代码。各位看官就当看看了。

最核心的部分在79行。table 的最低值会根据table的大小变化的。 table 显示的越大。下拉到最低端的时候，值就越远离Max值，也就是会越小。经过观察数据，发现要得到自动加载数据的判断条件是79行。

我这个只是单纯的从数据层面去找个结果。Java的内部原理并没有去深入了解。各位有什么好办法可以提供下。