Suggested way to encode name/value pairs in the Token of a GWT Activitie's place Token

Question

In GWT using the History/Activities/Places apis you end up with urls like this

http://192.168.0.104:8888/brokerage.html?gwt.codesvr=192.168.0.104:9997#StartPlace:params

Where the word params is the place "token" where parameters can be passed into the StartPlace object. For most of my applications a single string is enough to reload my data with refreshed is pressed. On a few Activities/Places/Pages however I need to split that Place token into a number of name/value pairs.

Does anybody have a suggestion for how to handle this? I am currently writing a class that builds a string out of name/value pairs by separating them in a url fashion using &name=value. It would be great if somebody knew of a class that could handle this or something.

Answer 1

String parameters="name1=value1&name2=value2&name3=value3";

HashMap<String, String> parameterMap = new HashMap<String, String>();

String[] parameterPairs = parameters.split("&");

for (int i = 0; i < parameterPairs.length; i++) {
    String[] nameAndValue = parameterPairs[i].split("=");
    parameterMap.put(nameAndValue[0], nameAndValue[1]);
}

....

String name1Value = parameterMap.get("name1");

This is all untested code, and it has unchecked array bounds! Make sure you don't have extraneous '&' or '=' signs, since they'll mess up the parsing.

Answer 2

How about simply copy/pasting the code from Window.Location for the parsing (private method buildListParamMap; you can also call it using JSNI –which allows bypassing Java visibility– given that it's a static method with no state), and UrlBuilder.buildString for the serialization?

Answer 3

This is what I came up with, it should work for others. Using a hash map is a good idea, I'll modify my code.

public static String parseNamedParam(String name, String token) {
    if (name == null || "".equals(name) || token == null || "".equals(token)) {
        return null;
    }
    final String[] strNameValuePairs = token.split("&");
    for (String entry : strNameValuePairs) {
        final String[] strNameValuePair = entry.split("=");
        final String decodedName = URL.decodeQueryString(strNameValuePair[0]);
        if (decodedName.equals(name)) {
            return URL.decodeQueryString(strNameValuePair[1]);
        }
    }
    return "";
}

And

public static String generateTokenString(List<TokenParam> tokenParams) {
    if (tokenParams == null || tokenParams.isEmpty()) {
        return "";
    }
    final StringBuilder sb = new StringBuilder();
    for (int i = 0; i < tokenParams.size(); i++) {
        final TokenParam tokenParam = tokenParams.get(i);
        final String nameEncoded = URL.encodeQueryString(tokenParam.getName());
        final String valueEncoded = URL.encodeQueryString(tokenParam.getValue());
        if (i != 0) {
            sb.append("&");
        }
        sb.append(nameEncoded);
        sb.append("=");
        sb.append(valueEncoded);
    }
    return sb.toString();
}