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How can i check File is Transfered/Copied completely in a folder,through a java code.

Posted on 2009-05-18
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Last Modified: 2013-11-23
My Friend is copying a large File in a specified folder.How can i check through java code that file transfer is completed.
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Question by:manzar_chaudhary
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15 Comments
 
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Expert Comment

by:CEHJ
ID: 24412151
Check the file size? ME5 sum?
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Author Comment

by:manzar_chaudhary
ID: 24412198
file.length() remains constant during the course of transfer.
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Expert Comment

by:Gibu George
ID: 24412270
You need to check the size of the file in the target folder  and then compare with source folder
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Author Comment

by:manzar_chaudhary
ID: 24412294
i don't have acces to the source folder.further if i check the filesize (file.length()) it is constant through out the transfer.
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Expert Comment

by:CEHJ
ID: 24412318
You can't tell if it's complete with certainty unless you know the source file size. When/if you do, you can compare the size as i mentioned.
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Expert Comment

by:CEHJ
ID: 24412326
>>i don't have acces to the source folder.

How do/can you transfer it then?
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Author Comment

by:manzar_chaudhary
ID: 24412455
As i said my friend is copying the file manually.I have a thread which monitors the specified folder.
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Expert Comment

by:CEHJ
ID: 24412486
Actually you didn't mention anything about manually. There is no way to know unless you somehow store the file's size in the file itself
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Author Comment

by:manzar_chaudhary
ID: 24412693
I have written following snippet and it worked but i don't know whether its a proper way to do it.
public static void main(String args[]){
        boolean flag = true;
        while(flag){
            File file  = new File("XXX.xxx");
            if(file.exists()){
                BufferedReader br;
                try {
                    Thread.sleep(1000);
                    br = new BufferedReader(new FileReader(file));
                    while(br.readLine() != null){
                        
                    }
                    System.err.println("File Copied..");
                    flag = false;
                } catch (Exception ex) {
                    System.err.println("File is Getting Copied..");
                    
                }
            }
        }
    }

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LVL 86

Expert Comment

by:CEHJ
ID: 24412730
You might try obtaining a lock on the File. It shouldn't let you if it's being written to
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LVL 86

Expert Comment

by:CEHJ
ID: 24412741
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Author Comment

by:manzar_chaudhary
ID: 24412797
yes you r write..but is there any harm in acquiring a lock..
actually windows(dnt know bout linux) locks the file while copying it and dosent release the lock  untill an unless it copies the file completely..i am just exploiting it..
thanks for suggesting a better way of accquiring a lock
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Expert Comment

by:CEHJ
ID: 24412823
>>yes you r write..but is there any harm in acquiring a lock..

None. As soon as you get it you can release it in a finally block
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Author Comment

by:manzar_chaudhary
ID: 24412844
so that means i can figure out whether file is getting tranfer or trasnferd completely using lock method.
do you think is there any other mechanism to do so...
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LVL 86

Accepted Solution

by:
CEHJ earned 50 total points
ID: 24412881
I think that's the simplest way, but i wouldn't like to say any is infallible unless it's the way i last mentioned. You should experiment
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