一个applet实时监测内存的问题

Question

package java2d;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.Date;
import javax.swing.*;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;public class MemoryMonitor extends JPanel {    static JCheckBox dateStampCB = new JCheckBox("Output Date Stamp");
    public Surface surf;
    JPanel controls;
    boolean doControls;
    JTextField tf;    public MemoryMonitor() {
        setLayout(new BorderLayout());
        setBorder(new TitledBorder(new EtchedBorder(), "Memory Monitor"));
        add(surf = new Surface());
        controls = new JPanel();
        controls.setPreferredSize(new Dimension(135,80));
        Font font = new Font("serif", Font.PLAIN, 10);
        JLabel label = new JLabel("Sample Rate");
        label.setFont(font);
        label.setForeground(Color.black);
        controls.add(label);
        tf = new JTextField("1000");
        tf.setPreferredSize(new Dimension(45,20));
        controls.add(tf);
        controls.add(label = new JLabel("ms"));
        label.setFont(font);
        label.setForeground(Color.black);
        controls.add(dateStampCB);
        dateStampCB.setFont(font);
        addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
               removeAll();
               if ((doControls = !doControls)) {
                   surf.stop();
                   add(controls);
               } else {
                   try { 
                       surf.sleepAmount = Long.parseLong(tf.getText().trim());
                   } catch (Exception ex) {}
                   surf.start();
                   add(surf);
               }
               validate();
               repaint();
            }
        });
    }
    public class Surface extends JPanel implements Runnable {        public Thread thread;
        public long sleepAmount = 1000;
        private int w, h;
        private BufferedImage bimg;
        private Graphics2D big;
        private Font font = new Font("Times New Roman", Font.PLAIN, 11);
        private Runtime r = Runtime.getRuntime();
        private int columnInc;
        private int pts[];
        private int ptNum;
        private int ascent, descent;
        private float freeMemory, totalMemory;
        private Rectangle graphOutlineRect = new Rectangle();
        private Rectangle2D mfRect = new Rectangle2D.Float();
        private Rectangle2D muRect = new Rectangle2D.Float();
        private Line2D graphLine = new Line2D.Float();
        private Color graphColor = new Color(46, 139, 87);
        private Color mfColor = new Color(0, 100, 0);
        private String usedStr;
              public Surface() {
            setBackground(Color.black);
            addMouseListener(new MouseAdapter() {
                public void mouseClicked(MouseEvent e) {
                    if (thread == null) start(); else stop();
                }
            });
        }        public Dimension getMinimumSize() {
            return getPreferredSize();
        }        public Dimension getMaximumSize() {
            return getPreferredSize();
        }        public Dimension getPreferredSize() {
            return new Dimension(135,80);
        }            

Answer 1

public void paint(Graphics g) {            if (big == null) {
                return;
            }            big.setBackground(getBackground());
            big.clearRect(0,0,w,h);            float freeMemory = (float) r.freeMemory();
            float totalMemory = (float) r.totalMemory();            // .. Draw allocated and used strings ..
            big.setColor(Color.green);
            big.drawString(String.valueOf((int) totalMemory/1024) + "K allocated",  4.0f, (float) ascent+0.5f);
            usedStr = String.valueOf(((int) (totalMemory - freeMemory))/1024) 
                + "K used";
            big.drawString(usedStr, 4, h-descent);            // Calculate remaining size
            float ssH = ascent + descent;
            float remainingHeight = (float) (h - (ssH*2) - 0.5f);
            float blockHeight = remainingHeight/10;
            float blockWidth = 20.0f;
            float remainingWidth = (float) (w - blockWidth - 10);            // .. Memory Free ..
            big.setColor(mfColor);
            int MemUsage = (int) ((freeMemory / totalMemory) * 10);
            int i = 0;
            for ( ; i < MemUsage ; i++) { 
                mfRect.setRect(5,(float) ssH+i*blockHeight,
                                blockWidth,(float) blockHeight-1);
                big.fill(mfRect);
            }            // .. Memory Used ..
            big.setColor(Color.green);
            for ( ; i < 10; i++)  {
                muRect.setRect(5,(float) ssH+i*blockHeight,
                                blockWidth,(float) blockHeight-1);
                big.fill(muRect);
            }            // .. Draw History Graph ..
            big.setColor(graphColor);
            int graphX = 30;
            int graphY = (int) ssH;
            int graphW = w - graphX - 5;
            int graphH = (int) remainingHeight;
            graphOutlineRect.setRect(graphX, graphY, graphW, graphH);
            big.draw(graphOutlineRect);            int graphRow = graphH/10;            // .. Draw row ..
            for (int j = graphY; j <= graphH+graphY; j += graphRow) {
                graphLine.setLine(graphX,j,graphX+graphW,j);
                big.draw(graphLine);
            }
        
            // .. Draw animated column movement ..
            int graphColumn = graphW/15;            if (columnInc == 0) {
                columnInc = graphColumn;
            }            for (int j = graphX+columnInc; j < graphW+graphX; j+=graphColumn) {
                graphLine.setLine(j,graphY,j,graphY+graphH);
                big.draw(graphLine);
            }            --columnInc;            if (pts == null) {
                pts = new int[graphW];
                ptNum = 0;
            } else if (pts.length != graphW) {
                int tmp[] = null;
                if (ptNum < graphW) {     
                    tmp = new int[ptNum];
                    System.arraycopy(pts, 0, tmp, 0, tmp.length);
                } else {        
                    tmp = new int[graphW];
                    System.arraycopy(pts, pts.length-tmp.length, tmp, 0, tmp.length);
                    ptNum = tmp.length - 2;
                }
                pts = new int[graphW];
                System.arraycopy(tmp, 0, pts, 0, tmp.length);
            } else {
                big.setColor(Color.yellow);
                pts[ptNum] = (int)(graphY+graphH*(freeMemory/totalMemory));
                for (int j=graphX+graphW-ptNum, k=0;k < ptNum; k++, j++) {
                    if (k != 0) {
                        if (pts[k] != pts[k-1]) {
                            big.drawLine(j-1, pts[k-1], j, pts[k]);
                        } else {
                            big.fillRect(j, pts[k], 1, 1);
                        }
                    }
                }
                if (ptNum+2 == pts.length) {
                    // throw out oldest point
                    for (int j = 1;j < ptNum; j++) {
                        pts[j-1] = pts[j];
                    }
                    --ptNum;
                } else {
                    ptNum++;
                }
            }
            g.drawImage(bimg, 0, 0, this);
        }
        public void start() {
            thread = new Thread(this);
            thread.setPriority(Thread.MIN_PRIORITY);
            thread.setName("MemoryMonitor");
            thread.start();
        }
        public synchronized void stop() {
            thread = null;
            notify();
        }
        public void run() {            Thread me = Thread.currentThread();            while (thread == me && !isShowing() || getSize().width == 0) {
                try {
                    thread.sleep(500);
                } catch (InterruptedException e) { return; }
            }
    
            while (thread == me && isShowing()) {
                Dimension d = getSize();
                if (d.width != w || d.height != h) {
                    w = d.width;
                    h = d.height;
                    bimg = (BufferedImage) createImage(w, h);
                    big = bimg.createGraphics();
                    big.setFont(font);
                    FontMetrics fm = big.getFontMetrics(font);
                    ascent = (int) fm.getAscent();
                    descent = (int) fm.getDescent();
                }
                repaint();
                try {
                    thread.sleep(sleepAmount);
                } catch (InterruptedException e) { break; }
                if (MemoryMonitor.dateStampCB.isSelected()) {
                     System.out.println(new Date().toString() + " " + usedStr);
                }
            }
            thread = null;
        }
    }
    public static void main(String s[]) {
        final MemoryMonitor demo = new MemoryMonitor();
        WindowListener l = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
            public void windowDeiconified(WindowEvent e) { demo.surf.start(); }
            public void windowIconified(WindowEvent e) { demo.surf.stop(); }
        };
        JFrame f = new JFrame("Java2D Demo - MemoryMonitor");
        f.addWindowListener(l);
        f.getContentPane().add("Center", demo);
        f.pack();
        f.setSize(new Dimension(200,200));
        f.setVisible(true);
        demo.surf.start();
    }
}
在html页面里一欠入.就是说找不到类.没办法载入...郁闷了..我还想在这基础上.连接数据库呢?请高手.帮助..