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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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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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by:CEHJ
ID: 24412151
Check the file size? ME5 sum?
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by:manzar_chaudhary
ID: 24412198
file.length() remains constant during the course of transfer.
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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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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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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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by:CEHJ
ID: 24412326
>>i don't have acces to the source folder.

How do/can you transfer it then?
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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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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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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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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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by:CEHJ
ID: 24412741
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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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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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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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CEHJ earned 150 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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