jdk7.0 新特性

jdk7.0 新特性

jdk7 增加了一个JLayer，用于在控件上方绘制一个新的图层。当然jdk6里只要在paint里也能做到，不过新特性方便了很多，最少你可以方便的为Jdk代码添加这些新特性。

public class Diva {   
public static void main(String[] args) {     
javax.swing.SwingUtilities.invokeLater(new Runnable() {       
public void run() {         createUI();       }     });   }    
public static void createUI() {     
JFrame f = new JFrame ("Diva");          LayerUI<JPanel> layerUI = new SpotlightLayerUI();     
JPanel panel = createPanel();     JLayer<JPanel> jlayer = new JLayer<JPanel>(panel, layerUI);          
f.add (jlayer);          f.setSize(300, 200);     
f.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);     
f.setLocationRelativeTo (null);     f.setVisible (true);   }    
private static JPanel createPanel() {     JPanel p = new JPanel();      
ButtonGroup entreeGroup = new ButtonGroup();     JRadioButton radioButton;     
p.add(radioButton = new JRadioButton("Beef", true));     entreeGroup.add(radioButton);     
p.add(radioButton = new JRadioButton("Chicken"));     entreeGroup.add(radioButton);     
p.add(radioButton = new JRadioButton("Vegetable"));     entreeGroup.add(radioButton);      
p.add(new JCheckBox("Ketchup"));     p.add(new JCheckBox("Mustard"));     
p.add(new JCheckBox("Pickles"));      p.add(new JLabel("Special requests:"));     
p.add(new JTextField(20));      JButton orderButton = new JButton("Place Order");     
p.add(orderButton);      return p;   } }  
class SpotlightLayerUI extends LayerUI<JPanel> {   
private boolean mActive;   private int mX, mY;    
@Override   public void installUI(JComponent c) {     
super.installUI(c);     JLayer jlayer = (JLayer)c;    
jlayer.setLayerEventMask(       AWTEvent.MOUSE_EVENT_MASK |       AWTEvent.MOUSE_MOTION_EVENT_MASK     );   }    
@Override   public void uninstallUI(JComponent c) {     JLayer jlayer = (JLayer)c;     jlayer.setLayerEventMask(0);     
super.uninstallUI(c);   }    
@Override   public void paint (Graphics g, JComponent c) {     Graphics2D g2 = (Graphics2D)g.create();      
// Paint the view.     super.paint (g2, c);      if (mActive) {       
// Create a radial gradient, transparent in the middle.       
java.awt.geom.Point2D center = new java.awt.geom.Point2D.Float(mX, mY);       
float radius = 72;       float[] dist = {0.0f, 1.0f};       
Color[] colors = {new Color(0.0f, 0.0f, 0.0f, 0.0f), Color.BLACK};       
RadialGradientPaint p =           new RadialGradientPaint(center, radius, dist, colors);       
g2.setPaint(p);       g2.setComposite(AlphaComposite.getInstance(           
AlphaComposite.SRC_OVER, .6f));       g2.fillRect(0, 0, c.getWidth(), c.getHeight());     }      
g2.dispose();   }    @Override   protected void processMouseEvent(MouseEvent e, JLayer l) {    
if (e.getID() == MouseEvent.MOUSE_ENTERED) mActive = true;     
if (e.getID() == MouseEvent.MOUSE_EXITED) mActive = false;     l.repaint();   }    
@Override   protected void processMouseMotionEvent(MouseEvent e, JLayer l) {     
Point p = SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), l);     mX = p.x;     mY = p.y;     l.repaint();   } }