SimpleDateFormat thread safety issues and solutions

SimpleDateFormat is a common class in Java that is used to parse and format date strings, but it can cause very subtle and difficult-to-debug problems if you use carelessness.

Because the DateFormat and SimpleDateFormat classes are not thread-safe, calling the format () and Parse () methods in a multithreaded environment should use synchronous code to avoid problems.
Or you can use threadlocal to turn shared variables into exclusive, and thread-exclusive will definitely be able to reduce the overhead of creating objects in a concurrent environment in a concurrency-exclusive way.
This approach is generally recommended if performance requirements are high.

1  Public classDateutil {2 3     Static FinalDateFormat SDF =NewSimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");4 5     StaticThreadlocal<dateformat> ThreadLocal =NewThreadlocal<dateformat>() {6         protectedDateFormat InitialValue () {7             return NewSimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");8         }9     };Ten  One     Private StaticDateFormat DateFormat () { A         //return SDF; -         returnthreadlocal.get (); -     } the  -      Public StaticDate Parse (String datestr)throwsParseException { -         returnDateFormat (). Parse (DATESTR); -     } +  -      Public StaticString Format (date date) { +         returnDateFormat (). Format (date); A     } at  -      Public Static voidMain (string[] args) { -          for(inti = 0; I < 3; i++) { -             NewThread () { -                  Public voidrun () { -                      while(true) { in                         Try { -Thread.Sleep (2000); to}Catch(interruptedexception E1) { + e1.printstacktrace (); -                         } the                          *                         Try { $System.out.println ( This. GetName () + ":" + dateutil.parse ("2013-05-24 06:02:20"));Panax Notoginseng}Catch(ParseException e) { - e.printstacktrace (); the                         } +                     } A                 } the }.start (); +         } -}

Reference:

Http://www.cnblogs.com/zemliu/p/3290585.html

Http://www.cnblogs.com/peida/archive/2013/05/31/3070790.html

SimpleDateFormat thread safety issues and solutions