How to calculate the file size downloaded and the total data to be downloaded in Java?

How to calculate the amount of data downloaded and the total data to b开发者_Python百科e downloaded in Java? E.G. 12kb/130kb...110kb/130kb

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If you mean downloading files via http using URLConnection, then you can

• get the Content-Length response header to get the total size. This is done via connection.getContentLength()
• to get the already downloaded amount, just count the bytes you have processed from the stream.

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To get amount of data that has been downloaded you can use CountingInputStream from Apache Commons IO. See http://commons.apache.org/io/apidocs/org/apache/commons/io/input/CountingInputStream.html Wrap your stream in it.

To get total length you need to use information from the server. For example, Content-Length header as previously mentioned. But it only works for http. It may not always be possible in generic case.