Java Trigger Crontrigger

Summary: Crontriggers is usually more useful than simpletrigger if you need to trigger tasks on a schedule like a calendar instead of every specific interval like simpletrigger.

I. web. XML:

<servlet><servlet-name>boot</servlet-name><servletclass>xxx.xx.x.bootservlet</ Servlet-class><load-on-startup>1</load-on-startup></servlet>

Ii. creation of Bootservlet.java

　　

public class Bootservlet extends HttpServlet {public  void init (servletconfig config) throws servletexception {    s Uper.init (config);    Initializes the database    new Srvinitdb (). Initdb ();    Start Alert trigger    Startexpenseremain ();  }    /***/public    void Startexpenseremain () {try {Scheduler Scheduler = Stdschedulerfactory.getdefaultscheduler ();　　Scheduler.start ();　　Once a week in Friday jobdetail expenseremindjob = new Jobdetail ("Expenseremindjob", Null,expenseremindjob.class);　　Crontrigger expenseremindjobtrigger=new Crontrigger ("Expenseremindjobtrigger");　　Expenseremindjobtrigger.setstarttime (New Date ()); Expenseremindjobtrigger.setcronexpression ("0 0 12?　　* FRI ");　Scheduler.schedulejob (Expenseremindjob, Expenseremindjobtrigger); } catch (Schedulerexception e) {e.printstacktrace ();} catch (ParseException e) {e.printstacktrace ()}}}

Iii. creation of Job:ExpenseRemindJob.java

public class Expenseremindjob implements job{public void execute (jobexecutioncontext arg0) throws Jobexecutionexception　　{  sendexpensesubjectremind ();  } /***/public synchronized void Sendexpensesubjectremind () {}}

Note:

Where new Crontrigger ("xxx"). Setcronexpression ("0 0 12? * FRI ");
A total of 7 sub-expressions all describe a separate schedule detail. These sub-expressions are separated by spaces, respectively:
1. Seconds sec
2. Minutes minutes
3. Hours hours
4. Days of the Day-of-month month
5 month
6. Day-of-week Days of the Week ("Mon-fri", "MON, WED, FRI" or even "Mon-wed,sat")
7. Year (optional field) (optional field)
The example string for a cron expression is "0 0 12?" * WED ", which means" 12:00 noon every Wednesday ".

All of the values in the domain have a specific legal scope, the legal range of these values is quite obvious, for example: the legal value of the second and the domain is 0 to 59, the legal range of the hour is 0 to 23,day-of-month is worth legal where the range is 0 to 31, but you need to be aware of the different days in different months. The legal value for the month is 0 to 11.

or use the string Jan,feb MAR, APR, May, June, JUL,, SEP, OCT, NOV and Dec to indicate. Days-of-week can be expressed in 1 to 7来 (1= Sunday) or in string Sun, MON, TUE, WED, THU, FRI, and Sat.

The wildcard character (' * ') can be used to represent "each" possible value in a domain. Therefore, the * in the month field represents each month, while the * in the Day-of-week field represents "Every day of the week".

‘?‘ Characters can be used in day-of-month and Day-of-week domains, which are used to denote "no value specified".
This is useful when you need to specify a value for one or two fields without having to set up other domains.

The '/' character is used to denote the increment of the value, for example, if the minute field is placed in ' 0/15 ', it means "every 15 minutes, starting from 0",
If you use ' 3/20 ' in the minute field, it means "every 20 minutes in the hour, starting from the 3rd minute" or the other same form is ' 3,23,43 '.

The ' L ' character can be used in Day-of-month and Day-of-week, which is a shorthand for "last", but has a different meaning in two domains.

For example, the "L" in the Day-of-month field represents the last day of the month, that is, 31st of January, non-leap year February of 28th.
If it is used in day-of-week, it means "7" or "SAT". However, if the character is followed by a different value in the Day-of-week field, the last week of the month is xxx.
For example: "6L" or "Fril" represents the last Friday of this month. When using the ' L ' option, the most important thing is not to specify a list or range of values, which can cause confusion.

The ' W ' character is used to specify the closest week (specified in the Day-of-week field) to the nearest day of the day.
For example: If you specify "15W" for the Day-of-month field, it means "the nearest week of the month 15th".

' # ' represents the first few weeks of the month. For example: "6#3" or "fri#3" in the Day-of-week field means "third Friday of the month".

Java Trigger Crontrigger