Talk a little more about How to lock a file - 未名空间MITBBS历史存档

国际科技财经博客移民网络热点娱乐民生时事公众号

Redian新闻

>未名空间

>Java - 爪哇娇娃

Talk a little more about How to lock a file

Talk a little more about How to lock a file# Java - 爪哇娇娃

d*o2001-01-09 08:01

1 楼

Thank you very much for all the discussion here!
I tried different ways and there is no perfect solution so
far.
1. I'd like to bring up another issue here:
The reason I want to lock a file is to prevent any other
access. But the other program has to know when the file is
released. In another word, other program has to know if the
file is being used. Let me make an example here:
In COM programming, after we create an intance of a COM, we
can call AddRef and Release to check how many instances

i*e2001-01-09 08:01

2 楼

You might have two ways to do it:
(1) use synchronization, synchronize on a common object,
like this,
synchronized( commonObject ) {
access the file;
}
or
(2) use a lock file , say myfile.lck
if ( lock file exits ) quit;
else {
create the lock file myfile.lck;
if (creation is successful) {
access the file;
remove the myfile.lck;

m*t2001-01-09 08:01

3 楼

ditto, are you saying it is actually a native legacy system
that would be writing the file? If that's the case, and you have
zero control on that system, the only solution I can
come up w/ is to write a native program to detect activities
on the file. You can call Win32 API to find out the process of
the legacy system which is holding the file handle, and keep
polling it until that file handle is released by the process.
This is, of course, based on an assumption that the legacy process
would