反复循环的进度条

import java.lang.reflect.InvocationTargetException;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.jface.dialogs.ProgressMonitorDialog;
import org.eclipse.jface.operation.IRunnableWithProgress;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;


public class TestProgress {
    static boolean stopflg = false;
    /** *//**
     * Launch the application
     * @param args
     */
    public static void main(String[] args) throws Exception{
        final Display display = Display.getDefault();
        final Shell shell = new Shell();
        shell.setSize(500, 375);
        shell.setText("SWT Application");
        
        //
        IRunnableWithProgress runnable = new IRunnableWithProgress(){
            public void run(IProgressMonitor monitor) throws InvocationTargetException, InterruptedException {
                monitor.beginTask("generate", 30);
                int i=0;
                while(true){
                    if(stopflg){
                        break;
                    }
                    i++;
                    if(i==30){
                        i=0;
                        monitor.beginTask("generate", 30);
                    }
                    monitor.worked(1);
                    Thread.sleep(100);
                }
                monitor.done();
            }
        };
        new ProgressMonitorDialog(shell).run(true, true, runnable);
        shell.open();
        shell.layout();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch())
                display.sleep();
        }
    }

}