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POHow can I identify different encodings without the use of a BOM?
 

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  1. POHow can I identify different encodings without the use of a BOM?
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    <p>I have a file watcher that is grabbing content from a growing file encoded with utf-16LE. The first bit of data written to it has the BOM available -- I was using this to identify the encoding against UTF-8 (which MOST of my files coming in are encoded in). I catch the BOM and re-encode to UTF-8 so my parser doesn't freak out. The problem is that since it's a growing file not every bit of data has the BOM in it.</p> <p>Here's my question -- without prepending the BOM bytes to each set of data I have (<strong>because I don't have control on the source</strong>) can I can just look for null bytes that are inherent in UTF-16 \000, and then use that as my identifier instead of the BOM? Will this cause me headaches down the road?</p> <p>My architecture involves a ruby web application logging the received data to a temporary file when my parser written in java picks it up.</p> <p>Write now my identification/re-encoding code looks like this:</p> <pre><code> // guess encoding if utf-16 then // convert to UTF-8 first try { FileInputStream fis = new FileInputStream(args[args.length-1]); byte[] contents = new byte[fis.available()]; fis.read(contents, 0, contents.length); if ( (contents[0] == (byte)0xFF) &amp;&amp; (contents[1] == (byte)0xFE) ) { String asString = new String(contents, "UTF-16"); byte[] newBytes = asString.getBytes("UTF8"); FileOutputStream fos = new FileOutputStream(args[args.length-1]); fos.write(newBytes); fos.close(); } fis.close(); } catch(Exception e) { e.printStackTrace(); } </code></pre> <p><strong>UPDATE</strong></p> <p>I want to support stuff like euros, em-dashes, and other characters as such. I modified the above code to look like this and it seems to pass all my tests for those characters:</p> <pre><code> // guess encoding if utf-16 then // convert to UTF-8 first try { FileInputStream fis = new FileInputStream(args[args.length-1]); byte[] contents = new byte[fis.available()]; fis.read(contents, 0, contents.length); byte[] real = null; int found = 0; // if found a BOM then skip out of here... we just need to convert it if ( (contents[0] == (byte)0xFF) &amp;&amp; (contents[1] == (byte)0xFE) ) { found = 3; real = contents; // no BOM detected but still could be UTF-16 } else { for(int cnt=0; cnt&lt;10; cnt++) { if(contents[cnt] == (byte)0x00) { found++; }; real = new byte[contents.length+2]; real[0] = (byte)0xFF; real[1] = (byte)0xFE; // tack on BOM and copy over new array for(int ib=2; ib &lt; real.length; ib++) { real[ib] = contents[ib-2]; } } } if(found &gt;= 2) { String asString = new String(real, "UTF-16"); byte[] newBytes = asString.getBytes("UTF8"); FileOutputStream fos = new FileOutputStream(args[args.length-1]); fos.write(newBytes); fos.close(); } fis.close(); } catch(Exception e) { e.printStackTrace(); } </code></pre> <p>What do you all think?</p>
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    1. USeyberg
    1. USeyberg
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    1. COI don't understand the problem (you refer to in the first paragraph). Of course not every fragment will have the BOM - but surely the beginning of the file. So for each file, remember whether you have seen the BOM, and if so, process it as UTF-16.
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      1. POHow can I identify different encodings without the use of a BOM?
      1. USMartin v. Löwis
    2. COSurely you don't have mixed encodings within a single file?
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      1. POHow can I identify different encodings without the use of a BOM?
      1. US1800 INFORMATION
    3. COI don't have control of the file that is growing -- that is why I can not simply rewind the file. I don't have mixed encodings within the same file -- but I DO have mixed encodings going across a network to a parser that accepts mixed encodings.
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      1. USeyberg
 

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