CODEWITHSUNDEEP
javaurl
Mridang Agarwalla
Mridang Agarwalla

Reputation: 45108

How can I append a query parameter to an existing URL?

I'd like to append key-value pair as a query parameter to an existing URL. While I could do this by checking for the existence of whether the URL has a query part or a fragment part and doing the append by jumping though a bunch of if-clauses but I was wondering if there was clean way if doing this through the Apache Commons libraries or something equivalent.

http://example.com would be http://example.com?name=John

http://example.com#fragment would be http://example.com?name=John#fragment

http://[email protected] would be http://[email protected]&name=John

http://[email protected]#fragment would be http://[email protected]&name=John#fragment

I've run this scenario many times before and I'd like to do this without breaking the URL in any way.

Upvotes: 102

Views: 248413

Answers (10)

Adam
Adam

Reputation: 36743

java.net.URI

This can be done by using the java.net.URI class to construct a new instance using the parts from an existing one, this should ensure it conforms to URI syntax.

The query part will either be null or an existing string, so you can decide to append another parameter with & or start a new query.

public class StackOverflow26177749 {

    public static URI appendUri(String uri, String appendQuery) throws URISyntaxException {
        URI oldUri = new URI(uri);
        
        String newQuery = oldUri.getQuery();
        if (newQuery == null) {
            newQuery = appendQuery;
        } else {
            newQuery += "&" + appendQuery;  
        }
        
        return new URI(oldUri.getScheme(), oldUri.getAuthority(),
                oldUri.getPath(), newQuery, oldUri.getFragment());
    }

    public static void main(String[] args) throws Exception {
        System.out.println(appendUri("http://example.com", "name=John"));
        System.out.println(appendUri("http://example.com#fragment", "name=John"));
        System.out.println(appendUri("http://[email protected]", "name=John"));
        System.out.println(appendUri("http://[email protected]#fragment", "name=John"));
    }
}

Shorter alternative

public static URI appendUri(String uri, String appendQuery) throws URISyntaxException {
    URI oldUri = new URI(uri);
    return new URI(oldUri.getScheme(), oldUri.getAuthority(), oldUri.getPath(),
            oldUri.getQuery() == null ? appendQuery : oldUri.getQuery() + "&" + appendQuery, oldUri.getFragment());
}

Output

    http://example.com?name=John
    http://example.com?name=John#fragment
    http://[email protected]&name=John
    http://[email protected]&name=John#fragment

Upvotes: 74

Erik van Velzen
Erik van Velzen

Reputation: 7062

With OkHttp3:

import okhttp3.HttpUrl;

HttpUrl url = HttpUrl.parse("https://example.com?name=John#fragment")
        .newBuilder()
        .addQueryParameter("email", "[email protected]")
        .build();

Upvotes: 0

Divyanshu Kumar
Divyanshu Kumar

Reputation: 1461

For Android, use this function to append a new parameter to your existing URI.

Java

private Uri appendUriParameter(Uri uri, String key, String newValue) {
  final Set<String> params = uri.getQueryParameterNames();
  final Uri.Builder newUri = uri.buildUpon().clearQuery();
  for (String param : params) {
    newUri.appendQueryParameter(param, uri.getQueryParameter(param));
  }
  newUri.appendQueryParameter(key, newValue);

  return newUri.build();
}

Kotlin

private fun appendUriParameter(uri: Uri, key: String, newValue: String) {
    val params = uri.queryParameterNames()
    val newUri = uri.buildUpon().clearQuery()
    for (param in params) {
        newUri.appendQueryParameter(param, uri.queryParameter(param))
    }
    return newUri.appendQueryParameter(key, newValue)
}

Upvotes: 2

Enrico Bianchi
Enrico Bianchi

Reputation: 2011

Using lambda and StringJoiner, code can be more concise:

public static URI appendUri(String url, Map<String, String> parameters) throws URISyntaxException {
    final var uri = new URI(url);
    final var sj = new StringJoiner("&");

    parameters.forEach((name, value) -> sj.add(name + "=" + value));
    final var query = uri.getQuery() == null ? sj.toString() : sj.length() > 0 ? uri.getQuery() + "&" + sj : uri.getQuery();

    return new URI(uri.getScheme(), uri.getUserInfo(), uri.getHost(), uri.getPort(), uri.getPath(), query, uri.getFragment());
}

Upvotes: 0

satyendra
satyendra

Reputation: 87

For android, Use: https://developer.android.com/reference/android/net/Uri#buildUpon()

URI oldUri = new URI(uri);
Uri.Builder builder = oldUri.buildUpon();
 builder.appendQueryParameter("newParameter", "dummyvalue");
 Uri newUri =  builder.build();

Upvotes: 7

Ananth George
Ananth George

Reputation: 9

An update to Adam's answer considering tryp's answer too. Don't have to instantiate a String in the loop.

public static URI appendUri(String uri, Map<String, String> parameters) throws URISyntaxException {
    URI oldUri = new URI(uri);
    StringBuilder queries = new StringBuilder();

    for(Map.Entry<String, String> query: parameters.entrySet()) {
        queries.append( "&" + query.getKey()+"="+query.getValue());
    }

    String newQuery = oldUri.getQuery();
    if (newQuery == null) {
        newQuery = queries.substring(1);
    } else {
        newQuery += queries.toString();
    }

    URI newUri = new URI(oldUri.getScheme(), oldUri.getAuthority(),
            oldUri.getPath(), newQuery, oldUri.getFragment());

    return newUri;
}

Upvotes: -1

Andrii Kovalchuk
Andrii Kovalchuk

Reputation: 4907

Kotlin & clean, so you don't have to refactor before code review:

private fun addQueryParameters(url: String?): String? {
        val uri = URI(url)

        val queryParams = StringBuilder(uri.query.orEmpty())
        if (queryParams.isNotEmpty())
            queryParams.append('&')

        queryParams.append(URLEncoder.encode("$QUERY_PARAM=$param", Xml.Encoding.UTF_8.name))
        return URI(uri.scheme, uri.authority, uri.path, queryParams.toString(), uri.fragment).toString()
    }

Upvotes: 0

tryp
tryp

Reputation: 1120

I suggest an improvement of the Adam's answer accepting HashMap as parameter

/**
 * Append parameters to given url
 * @param url
 * @param parameters
 * @return new String url with given parameters
 * @throws URISyntaxException
 */
public static String appendToUrl(String url, HashMap<String, String> parameters) throws URISyntaxException
{
    URI uri = new URI(url);
    String query = uri.getQuery();

    StringBuilder builder = new StringBuilder();

    if (query != null)
        builder.append(query);

    for (Map.Entry<String, String> entry: parameters.entrySet())
    {
        String keyValueParam = entry.getKey() + "=" + entry.getValue();
        if (!builder.toString().isEmpty())
            builder.append("&");

        builder.append(keyValueParam);
    }

    URI newUri = new URI(uri.getScheme(), uri.getAuthority(), uri.getPath(), builder.toString(), uri.getFragment());
    return newUri.toString();
}

Upvotes: 3

Nick Grealy
Nick Grealy

Reputation: 25942

There are plenty of libraries that can help you with URI building (don't reinvent the wheel). Here are three to get you started:

Java EE 7

import javax.ws.rs.core.UriBuilder;
...
return UriBuilder.fromUri(url).queryParam(key, value).build();

org.apache.httpcomponents:httpclient:4.5.2

import org.apache.http.client.utils.URIBuilder;
...
return new URIBuilder(url).addParameter(key, value).build();

org.springframework:spring-web:4.2.5.RELEASE

import org.springframework.web.util.UriComponentsBuilder;
...
return UriComponentsBuilder.fromUriString(url).queryParam(key, value).build().toUri();

See also: GIST > URI Builder Tests

Upvotes: 246

icza
icza

Reputation: 418575

Use the URI class.

Create a new URI with your existing String to "break it up" to parts, and instantiate another one to assemble the modified url:

URI u = new URI("http://[email protected]&name=John#fragment");

// Modify the query: append your new parameter
StringBuilder sb = new StringBuilder(u.getQuery() == null ? "" : u.getQuery());
if (sb.length() > 0)
    sb.append('&');
sb.append(URLEncoder.encode("paramName", "UTF-8"));
sb.append('=');
sb.append(URLEncoder.encode("paramValue", "UTF-8"));

// Build the new url with the modified query:
URI u2 = new URI(u.getScheme(), u.getAuthority(), u.getPath(),
    sb.toString(), u.getFragment());

Upvotes: 6

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