How to Extract Parameters from a Given Url

Getting URL parameter in java and extract a specific text from that URL

I think the one of the easiest ways out would be to parse the string returned by URL.getQuery() as

public static Map<String, String> getQueryMap(String query) {  
    String[] params = query.split("&");  
    Map<String, String> map = new HashMap<String, String>();

    for (String param : params) {  
        String name = param.split("=")[0];  
        String value = param.split("=")[1];  
        map.put(name, value);  
    }  
    return map;  
}

You can use the map returned by this function to retrieve the value keying in the parameter name.

How to extract parameters from a given url

It doesn't have to be regex. Since I think there's no standard method to handle this thing, I'm using something that I copied from somewhere (and perhaps modified a bit):

public static Map<String, List<String>> getQueryParams(String url) {
    try {
        Map<String, List<String>> params = new HashMap<String, List<String>>();
        String[] urlParts = url.split("\\?");
        if (urlParts.length > 1) {
            String query = urlParts[1];
            for (String param : query.split("&")) {
                String[] pair = param.split("=");
                String key = URLDecoder.decode(pair[0], "UTF-8");
                String value = "";
                if (pair.length > 1) {
                    value = URLDecoder.decode(pair[1], "UTF-8");
                }

                List<String> values = params.get(key);
                if (values == null) {
                    values = new ArrayList<String>();
                    params.put(key, values);
                }
                values.add(value);
            }
        }

        return params;
    } catch (UnsupportedEncodingException ex) {
        throw new AssertionError(ex);
    }
}

So, when you call it, you will get all parameters and their values. The method handles multi-valued params, hence the List<String> rather than String, and in your case you'll need to get the first list element.

Extract parameters from URL

Use it differently:

String decodedUrl = "www.foo.com";
URIBuilder builder = new URIBuilder(decodedUrl);
builder.addParameter("sign", "AZrhQaTRSiys5GZtlwZ+H3qUyIY=");
builder.addParameter("more", "boo");
List<NameValuePair> params = builder.getQueryParams();
String sign = params.get(0).getValue();

addParameter method is responsible for adding parameters as to the builder. The constructor of the builder should include the base URL only.

If this URL is given to you as is, then the + is already decoded and stands for the space character. If you are the one who generates this URL, you probably skipped the URL encoding step (which can be done using the code snipped above).

Read a bit about URL encoding: http://en.wikipedia.org/wiki/Query_string#URL_encoding

How do i get parameter value from url as string

You can do this:

String getTokenId(String url){

String[] splitUrl = url.split("user_token=");
String tokenId = "";

if(splitUrl.length >1){

for(int i =0; i < splitUrl[1].length(); i++){
    if(splitUrl[1].charAt(i) == '&'){
        tokenId = splitUrl[1].substring(0,i);
        break;
    }
}

}

return  tokenId;
}

But if you know the exact length of the token, it could be a search.

Extract parameter value from url using regular expressions

You almost had it, just need to escape special regex chars:

regex = /http\:\/\/www\.youtube\.com\/watch\?v=([\w-]{11})/;

url = 'http://www.youtube.com/watch?v=Ahg6qcgoay4';
id = url.match(regex)[1]; // id = 'Ahg6qcgoay4'

Edit: Fix for regex by soupagain.

How can I get parameters from a URL string?

You can use the parse_url() and parse_str() for that.

$parts = parse_url($url);
parse_str($parts['query'], $query);
echo $query['email'];

If you want to get the $url dynamically with PHP, take a look at this question:

Get the full URL in PHP

Get the values from the GET parameters (JavaScript)

JavaScript itself has nothing built in for handling query string parameters.

Code running in a (modern) browser can use the URL object (a Web API). URL is also implemented by Node.js:

// You can get url_string from window.location.href if you want to work with
// the URL of the current page
var url_string = "http://www.example.com/t.html?a=1&b=3&c=m2-m3-m4-m5"; 
var url = new URL(url_string);
var c = url.searchParams.get("c");
console.log(c);