Java - Convert String to valid URI object

Question

I am trying to get a java net URI object from a String  The string has some characters which will need to be replaced by their percentage escape sequences  But when I use URLEncoder to encode the String with UTF-8 encoding  even the   are replaced with their escape sequences   How can I get a valid encoded URL from a String object   http   www google com q a b gives http 3A 2F 2www google com    whereas I want the output to be http   www google com q a 20b  Can someone please tell me how to achieve this   I am trying to do this in an Android app  So I have access to a limited number of libraries

User · Answer

You can use the multi-argument constructors of the URI class. From the URI javadoc:

The multi-argument constructors quote illegal characters as required by the components in which they appear. The percent character ('%') is always quoted by these constructors. Any other characters are preserved.

So if you use

URI uri = new URI("http", "www.google.com?q=a b");

Then you get http:www.google.com?q=a%20b which isn't quite right, but it's a little closer.

If you know that your string will not have URL fragments (e.g. http://example.com/page#anchor), then you can use the following code to get what you want:

String s = "http://www.google.com?q=a b";
String[] parts = s.split(":",2);
URI uri = new URI(parts[0], parts[1], null);

To be safe, you should scan the string for # characters, but this should get you started.

User · Answer

If you don t like libraries  how about this   Note that you should not use this function on the whole URL  instead you should use this on the components   e g  just the  a b  component  as you build up the URL - otherwise the computer won t know what characters are supposed to have a special meaning and which ones are supposed to have a literal meaning       Converts a string into something you can safely insert into a URL     public static String encodeURIcomponent String s        StringBuilder o   new StringBuilder        for  char ch   s toCharArray              if  isUnsafe ch                 o append                   o append toHex ch   16                o append toHex ch   16                      else o append ch             return o toString       private static char toHex int ch        return  char  ch  lt  10    0    ch    A    ch - 10      private static boolean isUnsafe char ch        if  ch  gt  128    ch  lt  0          return true      return      amp          lt  gt     indexOf ch   gt   0

User · Answer

You might try  org apache commons httpclient util URIUtil encodeQuery in Apache commons-httpclient project  Like this  see URIUtil    URIUtil encodeQuery  http   www google com q a b     will become   http   www google com q a 20b   You can of course do it yourself  but URI parsing can get pretty messy

User · Answer

Well I tried using   String converted   URLDecoder decode  toconvert   UTF-8      I hope this is what you were actually looking for

User · Answer

Even if this is an old post with an already accepted answer  I post my alternative answer because it works well for the present issue and it seems nobody mentioned this method   With the java net URI library   URI uri   URI create URLString     And if you want a URL-formatted string corresponding to it   String validURLString   uri toASCIIString      Unlike many other methods  e g  java net URLEncoder  this one replaces only unsafe ASCII characters  like                In the above example  if URLString is the following String    http   www domain com fa  on word    the resulting validURLString will be    http   www domain com fa C3 A7on word    which is a well-formatted URL

User · Answer

I m going to add one suggestion here aimed at Android users   You can do this which avoids having to get any external libraries   Also  all the search replace characters solutions suggested in some of the answers above are perilous and should be avoided     Give this a try   String urlStr    http   abc dev domain com 0007AC ads 800x480 15sec h 264 mp4   URL url   new URL urlStr   URI uri   new URI url getProtocol    url getUserInfo    url getHost    url getPort    url getPath    url getQuery    url getRef     url   uri toURL      You can see that in this particular URL  I need to have those spaces encoded so that I can use it for a request     This takes advantage of a couple features available to you in Android classes   First  the URL class can break a url into its proper components so there is no need for you to do any string search replace work   Secondly  this approach takes advantage of the URI class feature of properly escaping components when you construct a URI via components rather than from a single string   The beauty of this approach is that you can take any valid url string and have it work without needing any special knowledge of it yourself

User · Answer

Android has always had the Uri class as part of the SDK  http   developer android com reference android net Uri html  You can simply do something like   String requestURL   String format  http   www example com  a  s amp b  s   Uri encode  foo bar    Uri encode  100  fubar d

User · Answer

I had similar problems for one of my projects to create a URI object from a string  I couldn t find any clean solution either  Here s what I came up with    public static URI encodeURL String url  throws MalformedURLException  URISyntaxException         URI uriFormatted   null        URL urlLink   new URL url       uriFormatted   new URI  http   urlLink getHost    urlLink getPath    urlLink getQuery    urlLink getRef          return uriFormatted      You can use the following URI constructor instead to specify a port if needed   URI uri   new URI scheme  userInfo  host  port  path  query  fragment

User · Answer

The java net blog had a class the other day that might have done what you want  but it is down right now so I cannot check      This code here could probably be modified to do what you want   http   svn apache org repos asf incubator shindig trunk java common src main java org apache shindig common uri UriBuilder java  Here is the one I was thinking of from java net  https   urlencodedquerystring dev java net

User · Answer

I ended up using the httpclient-4 3 6   import org apache http client utils URIBuilder  public static void main  String    args        URIBuilder uri   new URIBuilder        uri setScheme  http        setHost  www example com        setPath   somepage php        setParameter  username    Hello G  nter        setParameter  p1    parameter 1        System out println uri toString         Output will be   http   www example com somepage php username Hello G C3 BCnter p1 paramter 1

User · Answer

Or perhaps you could use this class   http   developer android com reference java net URLEncoder html  Which is present in Android since API level 1   Annoyingly however  it treats spaces specially  replacing them with   instead of  20   To get round this we simply use this fragment   URLEncoder encode value   UTF-8   replace        20

[java] Java - Convert String to valid URI object

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