How can I encode special character by URI correctly?

Question

I have created an URL to get the file on the server.

However, the file name may contains special characters like: ~!@#$%^&*() or some Asian characters like Japanese, Chinese and Korean.

I have read this article and adopt the solution:

String dwnStr= new String("http://") + `HOST_IP_ADDRESS` + new String('/')
                    + "picture/dog.jpg";
URL url= new URL(dwnStr);
URI uri= new URI(url.getProtocol(), url.getUserInfo(), url.getHost(), url.getPort(), url.getPath(), url.getQuery(), url.getRef()); // According to the official doc, it's in all cases.
url= uri.toURL();
(HttpURLConnection) url.openConnection();

And it gets well in the condition that if the dwnStr doesn't contain any special character.By contrast,if the dwnStr contains # hash mark, the URL constructor would drop the words after # , taking it as fragment identifier.

Thus, I tried another solution (still in the above link. This time, I avoid to use URL :

uri = new URI("http", null, HOST_IP_ADDRESS, 80, null,URLEncoder.encode("picture/dog.jpg", "UTF-8"), null);

It even can't work for the file name which doesn't contain any special characters.

What's the mistake I have made?

What strategy I can still adopt with?

ps: 1. I have tried the chosen solution in this article too. Of course, it doesn't work.

2. official doc link: official doc

Answer 1

You need to call the toASCIIString() method. It returns a String that you can send to the remote server.

Another option is to use the IDN class's static method toASCII .