title: How to check File integrity
body: <p>i'm developing an app that needs to download, every some minutes, some files.</p>
  
  <p>Using php, i list all the files and from java i get this list and check for file if is present or not. 
  Once downloaded it, i need to check for integrity because sometimes after the download, some files are corrupted.</p>
  
  <pre><code>try{
      String path = ...
      URL url = new URL(path);
      URLConnection conn = url.openConnection();
      conn.setDoOutput(true);         
      conn.setReadTimeout(30000);
      is = conn.getInputStream();
      ReadableByteChannel rbc = Channels.newChannel(is);
      FileOutputStream fos = null;
      fos = new FileOutputStream(local);
      fos.getChannel().transferFrom(rbc, 0, 1 &lt;&lt; 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;
  </code></pre>
  
  <p>What can i use in php and java to check for file integrity?</p>