一个定时器(使用的Timer类) 遇到一些问题:
写了一个定时器监听器,当启动服务器的时候,就启动了定时器;
问题是 :页面上有一个复选框,当选择的时候调用定时器,否则就停止调用, 怎么控制它??不知道该怎么去控制它.
写了一个定时器监听器,当启动服务器的时候,就启动了定时器;
问题是 :页面上有一个复选框,当选择的时候调用定时器,否则就停止调用, 怎么控制它??不知道该怎么去控制它.
变量可以根据需求设为类属性、存储在Session或数据库、或其他方式。
* This is the 3rd version of SwingWorker (also known as
* SwingWorker 3), an abstract class that you subclass to
* perform GUI-related work in a dedicated thread. For
* instructions on using this class, see:
*
* http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html
*
* Note that the API changed slightly in the 3rd version:
* You must now invoke start() on the SwingWorker after
* creating it.
*/
public abstract class SwingWorker {
private Object value; // see getValue(), setValue()
private Thread thread; /**
* Class to maintain reference to current worker thread
* under separate synchronization control.
*/
private static class ThreadVar {
private Thread thread;
ThreadVar(Thread t) { thread = t; }
synchronized Thread get() { return thread; }
synchronized void clear() { thread = null; }
} private ThreadVar threadVar; /**
* Get the value produced by the worker thread, or null if it
* hasn't been constructed yet.
*/
protected synchronized Object getValue() {
return value;
} /**
* Set the value produced by worker thread
*/
private synchronized void setValue(Object x) {
value = x;
} /**
* Compute the value to be returned by the <code>get</code> method.
*/
public abstract Object construct(); /**
* Called on the event dispatching thread (not on the worker thread)
* after the <code>construct</code> method has returned.
*/
public void finished() {
} /**
* A new method that interrupts the worker thread. Call this method
* to force the worker to stop what it's doing.
*/
public void interrupt() {
Thread t = threadVar.get();
if (t != null) {
t.interrupt();
}
threadVar.clear();
} /**
* Return the value created by the <code>construct</code> method.
* Returns null if either the constructing thread or the current
* thread was interrupted before a value was produced.
*
* @return the value created by the <code>construct</code> method
*/
public Object get() {
while (true) {
Thread t = threadVar.get();
if (t == null) {
return getValue();
}
try {
t.join();
}
catch (InterruptedException e) {
Thread.currentThread().interrupt(); // propagate
return null;
}
}
}
/**
* Start a thread that will call the <code>construct</code> method
* and then exit.
*/
public SwingWorker() {
final Runnable doFinished = new Runnable() {
public void run() { finished(); }
}; Runnable doConstruct = new Runnable() {
public void run() {
try {
setValue(construct());
}
finally {
threadVar.clear();
} SwingUtilities.invokeLater(doFinished);
}
}; Thread t = new Thread(doConstruct);
threadVar = new ThreadVar(t);
} /**
* Start the worker thread.
*/
public void start() {
Thread t = threadVar.get();
if (t != null) {
t.start();
}
}
}
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;class Example1 extends JPanel {
JProgressBar progressBar = new JProgressBar();
static int NUMLOOPS = 100;
JLabel statusField = new JLabel("Click Start to begin", JLabel.CENTER);
SwingWorker worker;
JButton startButton;
JButton interruptButton;
Border spaceBelow = BorderFactory.createEmptyBorder(0, 0, 5, 0); JButton getStartButton() {
return startButton;
} /**
* When the worker needs to update the GUI we do so by queuing
* a Runnable for the event dispatching thread with
* SwingUtilities.invokeLater(). In this case we're just
* changing the progress bars value.
*/
void updateStatus(final int i) {
Runnable doSetProgressBarValue = new Runnable() {
public void run() {
progressBar.setValue(i);
}
};
SwingUtilities.invokeLater(doSetProgressBarValue);
}
/**
* This method represents the application code that we'd like to
* run on a separate thread. It simulates slowly computing
* a value, in this case just a string 'All Done'. It updates the
* progress bar every half second to remind the user that
* we're still busy.
*/
Object doWork() {
try {
for(int i = 0; i < NUMLOOPS; i++) {
updateStatus(i);
if (Thread.interrupted()) {
throw new InterruptedException();
}
Thread.sleep(500);
}
}
catch (InterruptedException e) {
updateStatus(0);
return "Interrupted"; // SwingWorker.get() returns this
}
return "All Done"; // or this
}
/**
* This action listener, called by the "Start" button, effectively
* forks the thread that does the work.
*/
ActionListener startListener = new ActionListener() {
public void actionPerformed(ActionEvent event) {
startButton.setEnabled(false);
interruptButton.setEnabled(true);
statusField.setText("Working..."); /* Invoking start() on the SwingWorker causes a new Thread
* to be created that will call construct(), and then
* finished(). Note that finished() is called even if
* the worker is interrupted because we catch the
* InterruptedException in doWork().
*/
worker = new SwingWorker() {
public Object construct() {
return doWork();
}
public void finished() {
startButton.setEnabled(true);
interruptButton.setEnabled(false);
statusField.setText(get().toString());
}
};
worker.start();
}
};
/**
* This action listener, called by the "Cancel" button, interrupts
* the worker thread which is running this.doWork(). Note that
* the doWork() method handles InterruptedExceptions cleanly.
*/
ActionListener interruptListener = new ActionListener() {
public void actionPerformed(ActionEvent event) {
interruptButton.setEnabled(false);
worker.interrupt();
startButton.setEnabled(true);
}
}; /**
* And now for a little assembly. Put together the buttons, progress
* bar and status text field.
*/
Example1(String name) {
setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.black),name)); progressBar.setMaximum(NUMLOOPS); startButton = new JButton("Start");
startButton.addActionListener(startListener);
startButton.setEnabled(true); interruptButton = new JButton("Cancel");
interruptButton.addActionListener(interruptListener);
interruptButton.setEnabled(false); JComponent buttonBox = new JPanel();
buttonBox.add(startButton);
buttonBox.add(interruptButton); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
add(buttonBox);
add(progressBar);
add(statusField);
statusField.setAlignmentX(CENTER_ALIGNMENT); buttonBox.setBorder(spaceBelow);
Border pbBorder = progressBar.getBorder();
progressBar.setBorder(BorderFactory.createCompoundBorder(
spaceBelow,
pbBorder));
} Example1() {
this("Example 1");
}
}
import javax.swing.*; class Example2 extends Example1 { Example2() {
super("Example 2");
} /**
* Popup a modal confirm dialog and block until the user responds.
* Return true unless the user selects "NO".
*/
boolean waitForUserConfirmation() throws InterruptedException { /* We're going to show the modal dialog on the event dispatching
* thread with SwingUtilities.invokeLater(), so we create a
* Runnable class that shows the dialog and stores the user's
* response.
*/
class DoShowDialog implements Runnable {
boolean proceedConfirmed;
public void run() {
Object[] options = {"Continue", "Cancel"};
int n = JOptionPane.showOptionDialog(Example2.this,
"Example2: Continue?",
"Example2",
JOptionPane.YES_NO_OPTION,
JOptionPane.QUESTION_MESSAGE,
null,
options,
"Continue");
proceedConfirmed = (n == JOptionPane.YES_OPTION);
}
}
DoShowDialog doShowDialog = new DoShowDialog(); /* The invokeAndWait utility can throw an InterruptedException,
* which we don't bother with, and an InvocationException.
* The latter occurs if our Runnable throws - which would indicate
* a bug in DoShowDialog. The invokeAndWait() call will not return
* until the user has dismissed the modal confirm dialog.
*/
try {
SwingUtilities.invokeAndWait(doShowDialog);
}
catch (java.lang.reflect.InvocationTargetException e) {
e.printStackTrace();
}
return doShowDialog.proceedConfirmed;
}
public void getMyTread(){
SwingUtilities.invokeLater(new Runnable(){ @Override
public void run() {
// TODO Auto-generated method stub
}
});
}
/**
* This is just a copy of Example1.doWork() with one extra wrinkle.
* After about two seconds we ask the user to confirm with
* a modal dialog (see waitForUserConfirmation()); if the answer
* is NO then we short circuit.
*/
Object doWork() {
try {
for(int i = 0; i < NUMLOOPS; i++) {
updateStatus(i);
if (i == 4) {
if (!waitForUserConfirmation()) {
updateStatus(0);
return "Not Confirmed";
}
}
if (Thread.interrupted()) {
throw new InterruptedException();
}
Thread.sleep(500);
}
}
catch (InterruptedException e) {
updateStatus(0);
return "Interrupted"; // SwingWorker.get() returns this
}
return "All Done"; // or this
}
}
public class A{
protected ModelAndView handle(HttpServletRequest request,
HttpServletResponse response, Object command, BindException arg3)
throws Exception {
if("update".equals("operate")){
int flag;//这个就是复选框 选种与否的标记;(该标记也在数据库里面存着)
if(flag==0){
.........
return ModelAndView("a.jsp");
}else{
..........
return ModelAndView("b.jsp");
}
}}
}
页面提交是这样的
var forma = document.getElementById("form1");
forma.action="A.do?operateType=update&flag="+flag;还有个问题是我的定时器 run(){ }
中怎么能把上面写到的业务部分加进去?
import java.awt.event.*;
import java.io.File;
//import com.sun.java.swing.*; //old package name
import javax.swing.*; //new package namepublic class ThreadsExample { /**
* This is strictly boilerplate: set the look and feel, configure the
* frame, pack(), show().
*/
public static void main(String[] args) {
String laf = UIManager.getCrossPlatformLookAndFeelClassName();
try {
UIManager.setLookAndFeel(laf);
}
catch (Exception e) {
e.printStackTrace();
System.exit(1);
}
JFrame f = new JFrame("Worker Thread Examples");
WindowListener l = new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
};
f.addWindowListener(l); Container contentPane = f.getContentPane();
final Example1 ex1 = new Example1();
contentPane.setLayout(new GridLayout(1, 0));
contentPane.add(ex1);
contentPane.add(new Example2());
f.pack();
f.show();
// ex1.getStartButton().requestFocus();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
ex1.getStartButton().requestFocus(); //XXX: can't do this until now
}
});
}
}
public static void setStatus(boolean run){
... // 根据 run ，确定你的timer是否运行，至于怎么启动和终止，你自己解决
}
...
}2 在页面，当点击复选框是，调用后台的一个程序，让他直接调用那个 static 方法，比如 boolean run = .../
MyTimer.setStatus(run);// 这样就可以了！
至于怎么掉用？ 可以表单提交，也可以用Ajax 提交！
public static void setStatus(boolean run){
... // 根据 run ，确定你的timer是否运行，至于怎么启动和终止，你自己解决
}
...
}=======================前台可以用JS onclick或者onchangse 事件来写``