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POHow do I cater for empty strings while encoding parameters for a GET request?
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copied!<p>I'm working on a J2ME application that uses HTTP GET requests to communicate with a server. I already have a method to generate URL encoded parameters.</p> <p>In its present form it <em>can not</em> cater for empty strings,other code snippets I've seen have this deficiency as well, because they all rely on comparing the individual characters of a string argument.<a href="https://stackoverflow.com/q/12060061">I have previously asked a question related to this empty char dilemma</a></p> <p><strong>EDIT:</strong></p> <p>Requests to the server (Play 1.0) are in the form </p> <p><a href="http://server.com/setName/firstname/othername/lastname" rel="nofollow noreferrer">http://server.com/setName/firstname/othername/lastname</a></p> <p>Parameters cannot be null so http:server.com/setname/firstname//lastname is invalid</p> <p>The parameters are retrieved from a json object.Currently the url encoding method I have will encode all the extracted parameters correctly and leave any character which cannot be converted as is.A space in a string as in "Jo e" and space character itself will be encoded as Jo%20e and %20 respectively. The JSON object</p> <pre><code>{ "firstname":"joe" "othername":"" "lastname":"bloggs" } </code></pre> <p>will however result in the invalid url <a href="http://server.com/setname/joe//bloggs" rel="nofollow noreferrer">http://server.com/setname/joe//bloggs</a> because the othername parameter is an empty string and is left as such by my method.</p> <p>I could check that the string about to be returned is empty and return a space character instead. But I'm wondering if there isn't a better modification to this method or a whole new approach which would be more robust?</p> <pre><code> public static String urlEncode(String s) { ByteArrayOutputStream bOut = null; DataOutputStream dOut = null; ByteArrayInputStream bIn = null; StringBuffer ret = new StringBuffer(); try { bOut=new ByteArrayOutputStream(); dOut = new DataOutputStream(bOut); //return value dOut.writeUTF(s); bIn = new ByteArrayInputStream(bOut.toByteArray()); bIn.read(); bIn.read(); int c = bIn.read(); while (c >= 0) { if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '.' || c == '-' || c == '*' || c == '_') { ret.append((char) c); } else if (c == ' ' ) { //ret.append('+'); ret.append("%20"); } else { if (c < 128) { appendHex(c, ret); } else if (c < 224) { appendHex(c, ret); appendHex(bIn.read(), ret); } else if (c < 240) { appendHex(c, ret); appendHex(bIn.read(), ret); appendHex(bIn.read(), ret); } } c = bIn.read(); } } catch (IOException ioe) { System.out.println("urlEncode:"+ioe); return s; } return ret.toString(); } private static void appendHex(int arg0, StringBuffer buff) { buff.append('%'); if (arg0 < 16) { buff.append('0'); } buff.append(Integer.toHexString(arg0)); } </code></pre>

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