Tutorial :What is the idiomatic way to compose a URL or URI in Java?


How do I build a URL or a URI in Java? Is there an idiomatic way, or libraries that easily do this?

I need to allow starting from a request string, parse/change various URL parts (scheme, host, path, query string) and support adding and automatically encoding query parameters.


As of Apache HTTP Component HttpClient 4.1.3, from the official tutorial:

public class HttpClientTest {  public static void main(String[] args) throws URISyntaxException {      List<NameValuePair> qparams = new ArrayList<NameValuePair>();      qparams.add(new BasicNameValuePair("q", "httpclient"));      qparams.add(new BasicNameValuePair("btnG", "Google Search"));      qparams.add(new BasicNameValuePair("aq", "f"));      qparams.add(new BasicNameValuePair("oq", null));      URI uri = URIUtils.createURI("http", "www.google.com", -1, "/search",                                   URLEncodedUtils.format(qparams, "UTF-8"), null);      HttpGet httpget = new HttpGet(uri);      System.out.println(httpget.getURI());      //http://www.google.com/search?q=httpclient&btnG=Google+Search&aq=f&oq=  }  }  

Edit: as of v4.2 URIUtils.createURI() has been deprecated in favor of URIBuilder:

URI uri = new URIBuilder()          .setScheme("http")          .setHost("www.google.com")          .setPath("/search")          .setParameter("q", "httpclient")          .setParameter("btnG", "Google Search")          .setParameter("aq", "f")          .setParameter("oq", "")          .build();  HttpGet httpget = new HttpGet(uri);  System.out.println(httpget.getURI());  


Apache HTTPClient?


As the author, I'm probably not the best person to judge if my URL/URI builder is good, but here it nevertheless is: https://github.com/mikaelhg/urlbuilder

I wanted the simplest possible complete solution with zero dependencies outside the JDK, so I had to roll my own.


Using HTTPClient worked well.

protected static String createUrl(List<NameValuePair> pairs) throws URIException{      HttpMethod method = new GetMethod("http://example.org");    method.setQueryString(pairs.toArray(new NameValuePair[]{}));      return method.getURI().getEscapedURI();    }  


Bug (RFE) 6306820 in the java bug database adresses this.

In one of the comments, a link to the RFE implementation is provided.


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();  


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


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

See also: GIST > URI Builder Tests


Use OkHttp

It's 2017 and there is a very popular library named OkHttp which has been starred 20K times on GitHub. With this library, you can build an url like below:

import okhttp3.HttpUrl;    URL url = new HttpUrl.Builder()      .scheme("http")      .host("example.com")      .port(4567)      .addPathSegments("foldername/1234")      .addQueryParameter("abc", "xyz")      .build().url();  


After being lambasted for suggesting the URL class. I will take the commenter's advice and suggest the URI class instead. I suggest you look closely at the constructors for a URI as the class is very immutable once created.
I think this constructor allows you to set everything in the URI that you could need.

URI(String scheme, String userInfo, String host, int port, String path, String query, String fragment)            Constructs a hierarchical URI from the given components.  


The URL class has pretty good methods for constructing a URL.

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