如何使JScrollPane可调整大小

像这样，我有一个带有JMenuBar和JToolBar的JFrame。然后，使用MigLayout添加了两个JScrollPane，它们的宽度分别为15％和85％，并分别包含JTree和JPanel。有什么方法可以动态调整两个JScrollpanes的大小？谁能分享任何资源？这是我的做法：

package ui;
import java.awt.Color;  
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JToolBar;
import javax.swing.JTree;
import javax.swing.SwingConstants;
import javax.swing.UIManager;
import javax.swing.tree.DefaultMutableTreeNode;
import com.jtattoo.plaf.aluminium.AluminiumLookAndFeel;
import net.miginfocom.swing.MigLayout;

public class MainFrameView 
{
    private JFrame workingFrame;
    private JPanel footerPanel;
    private JScrollPane leftScrollPane,rightScrollPane;
    private JMenuBar mainMenuBar;
    private JToolBar headerToolBar;
    private JTree exploreTree;

    public void createMainFrame()
    {

        workingFrame = new JFrame("Demo");
        workingFrame.setLayout(new MigLayout("","[grow]","[grow]"));
        workingFrame.setJMenuBar(getMainMenuBar());
        workingFrame.add(getHeaderToolbar(),"dock north");
        workingFrame.add(getLeftScrollPane(),"dock west, width 15%!");        
        workingFrame.add(getRightScrollPane(),"dock east, width 85%!");
        workingFrame.setSize(940, 500);
        workingFrame.setMinimumSize(new Dimension(700,400));
        workingFrame.setVisible(true);
        workingFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    private JMenuBar getMainMenuBar()
    {
        mainMenuBar = new JMenuBar();
        mainMenuBar.setLayout(new MigLayout("inset 0"));

        JMenu[] menu = new JMenu[5]; 
        for(int i=0;i<5;i++)
        {
            menu[i]=new JMenu("Menu-"+Integer.toString(i+1));
            menu[i].setHorizontalTextPosition(SwingConstants.CENTER);
            menu[i].setVerticalTextPosition(SwingConstants.BOTTOM);
            mainMenuBar.add(menu[i]);
        }
        return mainMenuBar;
    }

    private JToolBar getHeaderToolbar()
    {
        headerToolBar = new JToolBar();
        headerToolBar.setFloatable(false);
        headerToolBar.setLayout(new MigLayout("inset 1px"));
        headerToolBar.add(new JButton("B1"));
        headerToolBar.add(new JButton("B2"));
        headerToolBar.add(new JButton("B3"));
        headerToolBar.add(new JButton("B4"));
        headerToolBar.add(new JButton("B5"));

        return headerToolBar;
    }

    private JScrollPane getLeftScrollPane()
    {
        leftScrollPane = new JScrollPane(getExploreTree());
        leftScrollPane.setOpaque(false);
        leftScrollPane.getViewport().setOpaque(false);
        leftScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        leftScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        return leftScrollPane;
    }


    private JTree getExploreTree()
    {
        DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Menu");

            DefaultMutableTreeNode firstNode = new DefaultMutableTreeNode("Node 1");
                firstNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                firstNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                firstNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                firstNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                firstNode.add(new DefaultMutableTreeNode("Sub Node 5"));

            DefaultMutableTreeNode secondNode = new DefaultMutableTreeNode("Node2");
                secondNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                secondNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                secondNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                secondNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                secondNode.add(new DefaultMutableTreeNode("Sub Node 5"));

            DefaultMutableTreeNode thirdNode = new DefaultMutableTreeNode("Node 3");
                thirdNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                thirdNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                thirdNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                thirdNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                thirdNode.add(new DefaultMutableTreeNode("Sub Node 5"));

            DefaultMutableTreeNode fourthNode = new DefaultMutableTreeNode("Node4");
                fourthNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                fourthNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                fourthNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                fourthNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                fourthNode.add(new DefaultMutableTreeNode("Sub Node 5"));   

            DefaultMutableTreeNode fifthNode = new DefaultMutableTreeNode("Node 5");
                fifthNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                fifthNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                fifthNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                fifthNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                fifthNode.add(new DefaultMutableTreeNode("Sub Node 5"));

            DefaultMutableTreeNode sixthNode = new DefaultMutableTreeNode("Node6");
                sixthNode.add(new DefaultMutableTreeNode("Sub Node 1"));
                sixthNode.add(new DefaultMutableTreeNode("Sub Node 2"));
                sixthNode.add(new DefaultMutableTreeNode("Sub Node 3"));
                sixthNode.add(new DefaultMutableTreeNode("Sub Node 4"));
                sixthNode.add(new DefaultMutableTreeNode("Sub Node 5"));    

            rootNode.add(firstNode);
            rootNode.add(secondNode); 
            rootNode.add(thirdNode);
            rootNode.add(fourthNode); 
            rootNode.add(fifthNode);
            rootNode.add(sixthNode);

        UIManager.put("Tree.rendererFillBackground", false);
        exploreTree = new JTree(rootNode);
        exploreTree.setOpaque(false);
        exploreTree.setRootVisible(false);
        return exploreTree;
    }


    private JScrollPane getRightScrollPane()
    {
        JPanel j = new JPanel(new MigLayout("width 1500px!, height 1500px!"));
        j.setBackground(new Color(200,200,200));

        rightScrollPane = new JScrollPane();
        rightScrollPane.setViewportView(j);
        rightScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
        rightScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        return rightScrollPane;
    }
}