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。