请教一applet技术问题,急救

[64288]

我发现applet技术运行有init(),start(),stop（），destory（），在这四种运行方式下，都不能做到：当我最小化窗口时，程序还在不停的运行。而我要求的是，只要IE进入这页面，程序每隔一定时间，运行程序，也就是能够使程序不受用户的影响（条件是：用户不关闭IE）

[chinadbzy]

你是想做实时数据哪种吧.

建议你在Applet中开辟一个线程..来监听时间..一定时间取一次数据.

JDK的本身例子中有一个.监视内存的.哪里就调用了.时间.

我们现在做的项目实时曲线中也涉及到了.这个问题.

你看这个例子对你有没有帮助.

[chinadbzy]

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;

/**
* Tracks Memory allocated & used, displayed in graph form.
*/
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);
}


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);
}

[chinadbzy]

--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();
}
}

[64288]

没注解的呀，能给我个注解的吗？我刚学jdk，好多函数都不是很清楚

[Yujlyjl]

记号，以后再看

[jilu_sun]

帮顶！顺便学习！

[XIHSHI]

UP

[cmengzhongren]

准备学习

[oceanrock]

留下。