java-如何实现timer功能

2004-11-8
author :meanson wang
email:meansonw@hotmail.com
date:2004-11-8
java-如何实现timer功能

1.listener class
package timer;

import java.util.timertask;
import java.util.timer;
import javax.servlet.*;

public class remindlistener implements servletcontextlistener {
private java.util.timer timer = null;
public void contextinitialized(servletcontextevent sce) {
timer = new java.util.timer(true);
sce.getservletcontext().log(new java.util.date()+"timer start up!");
timer.schedule(new remindtask(),0,1*60*1000);//1 minute roll
sce.getservletcontext().log(new java.util.date()+"schedule loaded!");
}
public void contextdestroyed(servletcontextevent sce) {
timer.cancel();
sce.getservletcontext().log(new java.util.date()+"timer destroyed!");
}

}

2.task class
package timer;

import java.util.timertask;
import java.util.calendar;

public class remindtask extends timertask{
private static final int c_schedule_hour = 15;
private static boolean isrunning = false;
public remindtask() {

}
public void run() {
calendar cal = calendar.getinstance();
if (!isrunning) {
if (c_schedule_hour == cal.get(calendar.hour_of_day)) {
isrunning = true;
system.out.println(new java.util.date()+"task start");
//todo for example
int i = 0;
while (i++ < 10) {
system.out.println(new java.util.date()+"done!task" + i + "/" + 10);
}
isrunning = false;
system.out.println(new java.util.date()+"all task done!");
}
}
else
{
system.out.println(new java.util.date()+"task existed!");
}
}
}

3.loadonstart in web.xml
<listener>
<listener-class>timer.remindlistener</listener-class>
</listener>

4.restart server