Currently I use while(true) and Thread.sleep() for checking for new records in the db and execute java code.

Here is an example:

public class StartCommands implements Runnable{

private Active_Job activeJob;

Runnable execute_command;

public StartCommands(){

activeJobs = new Active_Job();

}

@Override

public void run(){

int jobId = 0;

while(true){

//access the db and get one row from the table by the status

jobId = activeJobs.get(Status.NEW);

if (jobId > 0){

activeJob.updateStatus(Status.INIT);

execute_command = activeJob.getCommand();

new Thread(execute_command).start();

activeJob = new Active_Job();

jobId = 0;

}

Thread.sleep(10*1000);

}

}

}

I've few places in the code that I use this method. But I dont like the endless loop and check every 10 seconds for new row.

So what I'm looking for is some kind of listener: once new record has been entered - execute java code. Some of the inserts executed from the application and some are not.

解决方案

There is no builtin "update listener" in MySQL (or any SQL database I'm aware of), so you have to build your own.

Notice that in your implementation, if two new rows are added you will handle one, wait 10 seconds, then handle the next one. Your code cannot handle more than one event every 10 seconds.

What you want to do is separate the polling of the database from the dispatching of the worker threads. Have the polling loop wake up every n seconds, read ALL new records from the database, and add them to a work queue. Have a consumer thread that is waiting on the queue and launches processors as messages appear on the queue. using a thread pool implementation.