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POWhy does Java automatically decode %2F in URI encoded filenames?
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copied!<p>I have a servlet that needs to write out files that have a user-configurable name. I am trying to use URI encoding to properly escape special characters, but the JRE appears to automatically convert encoded forward slashes <code>%2F</code> into path separators.</p> <p>Example:</p> <pre><code>File dir = new File("C:\Documents and Setting\username\temp"); String fn = "Top 1/2.pdf"; URI uri = new URI( dir.toURI().toASCIIString() + URLEncoder.encoder( fn, "ASCII" ).toString() ); File out = new File( uri ); System.out.println( dir.toURI().toASCIIString() ); System.out.println( URLEncoder.encode( fn, "ASCII" ).toString() ); System.out.println( uri.toASCIIString() ); System.out.println( output.toURI().toASCIIString() ); </code></pre> <p>The output is:</p> <pre><code>file:/C:/Documents%20and%20Settings/username/temp/ Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1%2F2.pdf file:/C:/Documents%20and%20Settings/username/temp/Top+1/2.pdf </code></pre> <p>After the new File object is instantiated, the <code>%2F</code> sequence is automatically converted to a forward slash and I end up with an incorrect path. Does anybody know the proper way to approach this issue? </p> <p>The core of the problem seems to be that</p> <pre><code>uri.equals( new File(uri).toURI() ) == FALSE </code></pre> <p>when there is a <code>%2F</code> in the URI.</p> <p>I'm planning to just use the URLEncoded string verbatim rather than trying to use the <code>File(uri)</code> constructor.</p>

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