php - How to check File integrity -

i'm developing app needs download, every minutes, files.

using php, list files , java list , check file if present or not. once downloaded it, need check integrity because after download, files corrupted.

try{     string path = ...     url url = new url(path);     urlconnection conn = url.openconnection();     conn.setdooutput(true);              conn.setreadtimeout(30000);     = conn.getinputstream();     readablebytechannel rbc = channels.newchannel(is);     fileoutputstream fos = null;     fos = new fileoutputstream(local);     fos.getchannel().transferfrom(rbc, 0, 1 << 24);     fos.close();     rbc.close(); } catch (filenotfoundexception e) {     if(new file(local).exists()) new file(local).delete();        return false; } catch (ioexception e) {     if(new file(local).exists()) new file(local).delete();        return false; } catch (ioexception e) {     if(new file(local).exists()) new file(local).delete();        return false; }  return false; 

what can use in php , java check file integrity?

maintain checksum list on server, download file, generate checksum of downloaded file , check if same 1 on server. if is, file fine.