G S Sundar wrote:
> Hello All,
> I'm facing problem, while creating a new thread/timer inside the Servlet init()
> method. In init method i'm loading text file(s), and updating them in my
> servlet context. When i update/change my text file(s) i need to restart my
> servlet runner to update the file contents in Servlet Context.
> I want to update the file contents without restarting the servlet runner, for
> that i tried with Thread/Timer class. For the specified interval it will check
> the file status and update the servlet context if there is any change in file.
> Otherwise it should return to the main thread.
> But once my thread/timer start() begins it's not at all coming back to the main
> thread.
> I think my thread is running inside the main thread(INIT), and there is no
> specific condition to exit/stop my thread, bcoz it should work like demon
> process. In this how can i pass the control back to the main thread.
>
> Due to this reason init methd is not getting completed, and i'm not able to run
> my servlet. expecting help in this regard.
>
> Thanx in advance..
>
> Regards
> G S Sundaram
> [...]
Hi :-) I did a simple testing, just as a reference :
- make a "timer" with a helper class implementing Runnable
- in this "timer", change a Attribute of ServletContext periodcally
(every 10 seconds)
- in service(...) of myServlet, for every client' requesting, print
this Attribute of ServletContext, so we can see the changing.
******** the following is the code: ********
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class servlet_iT extends HttpServlet{ //iT=insideThread
static byte [] ctxLocker=new byte[0];
static ServletContext ctx;
public void init(ServletConfig config) throws ServletException {
super.init(config);
synchronized(servlet_iT.ctxLocker){
ctx=this.getServletContext();
}
try{
new Thread( servlet_iT_Helper.getOnlyOneInstance(), "insideThread" ).start();
}catch(Exception e){ System.out.println("servlet_iT_Helper, e="+e); }
System.out.println("in init...");
}
public void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
synchronized(servlet_iT.ctxLocker){
System.out.println( "name0="+servlet_iT.ctx.getAttribute("name0") );
}
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<HTML><BODY>");
out.println("ok");
out.println("</BODY></HTML>");
out.close();
//return;
}
}
class servlet_iT_Helper implements Runnable, Serializable{
private static servlet_iT_Helper onlyOneInstance;
private /*static*/ int counter=0;
private servlet_iT_Helper(){}
public static synchronized servlet_iT_Helper getOnlyOneInstance() {
if (onlyOneInstance == null) {
onlyOneInstance = new servlet_iT_Helper();
}
return onlyOneInstance;
}
public void run(){
while(true){
counter++;
System.out.println("in run, counter="+counter);
synchronized(servlet_iT.ctxLocker){
servlet_iT.ctx.setAttribute( "name0", String.valueOf(counter) );
}
try{
Thread.currentThread().sleep(10000);
}catch(Exception e){ System.out.println("servlet_iT_Helper, e="+e); }
}
}
}
Bo
Feb.12, 2001
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