Java基础之创建窗口——使用SpringLayout管理器（TrySpringLayout）

控制台程序。

可以把JFrame对象aWindow的内容面板的布局管理器设置为javax.swing.SpringLayout管理器。

SpringLayout类定义的布局管理器根据javax.swing.Spring对象定义的一组约束，决定容器中每个组件的位置和大小。在使用SpringLayout管理器的容器中，每个组件都有与之关联的SpringLayout.Constrains对象，Constrains对象定义了组件的4条边的位置。在访问组件对象关联的SpringLayout.Constrains对象之前，必须先把组件添加到容器中。

 import javax.swing.*;

 import java.awt.*;

 public class TrySpringLayout {

   public static void createWindow(){

     JFrame aWindow = new JFrame("This is the Window Title");

     Toolkit theKit = aWindow.getToolkit();                             // Get the window toolkit

     Dimension wndSize = theKit.getScreenSize();                        // Get screen size

     // Set the position to screen center & size to half screen size

     aWindow.setSize(wndSize.width/2, wndSize.height/2);                // Set window size

     aWindow.setLocationRelativeTo(null);                               // Center window

     aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

     SpringLayout layout = new SpringLayout();                          // Create a layout manager

     Container content = aWindow.getContentPane();                      // Get the content pane

     content.setLayout(layout);                                         // Set the container layout mgr

     JButton[] buttons = new JButton[6];                                // Array to store buttons

     SpringLayout.Constraints constr = null;

     for(int i = 0; i < buttons.length; ++i) {

       buttons[i] = new JButton("Press " + (i+1));

       content.add(buttons[i]);                                         // Add a Button to content pane

    }

     Spring xSpring = Spring.constant(5,15,25);                         // x constraint for first button

     Spring ySpring = Spring.constant(10,30, 50);                       // y constraint for first button

     // Connect x,y for first button to left and top of container by springs

     constr = layout.getConstraints(buttons[0]);

     constr.setX(xSpring);

     constr.setY(ySpring);

     // Hook buttons together with springs

     for(int i = 1 ; i< buttons.length ; ++i) {

       constr = layout.getConstraints(buttons[i]);

       layout.putConstraint(SpringLayout.WEST, buttons[i],

                              xSpring,SpringLayout.EAST, buttons[i-1]);

       layout.putConstraint(SpringLayout.NORTH, buttons[i],

                              ySpring,SpringLayout.SOUTH, buttons[i-1]);

     }

     // Uncomment the following code to constrain the content pane

 /*

     SpringLayout.Constraints constraint = layout.getConstraints(content);

     constraint.setConstraint(SpringLayout.EAST,

                              Spring.sum(constr.getConstraint(SpringLayout.EAST),

                              Spring.constant(15)));

     constraint.setConstraint(SpringLayout.SOUTH,

                              Spring.sum(constr.getConstraint(SpringLayout.SOUTH),

                              Spring.constant(10)));

     aWindow.pack();

 */

     aWindow.setVisible(true);                                          // Display the window

   }

   public static void main(String[] args) {

     SwingUtilities.invokeLater(new Runnable() {

             public void run() {

                 createWindow();

             }

         });

   }

 }

SpringLayout管理器非常灵活，如果对组件设置了合适的约束，就可以完成许多其他布局管理器的工作。