Asked  6 Months ago    Answers:  5   Viewed   30 times

In Java, I want to convert this:

https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest_type

To this:

https://mywebsite/docs/english/site/mybook.do&request_type

This is what I have so far:

class StringUTF 
{
    public static void main(String[] args) 
    {
        try{
            String url = 
               "https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do" +
               "%3Frequest_type%3D%26type%3Dprivate";

            System.out.println(url+"Hello World!------->" +
                new String(url.getBytes("UTF-8"),"ASCII"));
        }
        catch(Exception E){
        }
    }
}

But it doesn't work right. What are these %3A and %2F formats called and how do I convert them?

 Answers

30

This does not have anything to do with character encodings such as UTF-8 or ASCII. The string you have there is URL encoded. This kind of encoding is something entirely different than character encoding.

Try something like this:

try {
    String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8.name());
} catch (UnsupportedEncodingException e) {
    // not going to happen - value came from JDK's own StandardCharsets
}

Java 10 added direct support for Charset to the API, meaning there's no need to catch UnsupportedEncodingException:

String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8);

Note that a character encoding (such as UTF-8 or ASCII) is what determines the mapping of characters to raw bytes. For a good intro to character encodings, see this article.

Tuesday, June 1, 2021
 
superfell
answered 6 Months ago
59

URLEncoder is the way to go. You only need to keep in mind to encode only the individual query string parameter name and/or value, not the entire URL, for sure not the query string parameter separator character & nor the parameter name-value separator character =.

String q = "random word £500 bank $";
String url = "https://example.com?q=" + URLEncoder.encode(q, StandardCharsets.UTF_8);

When you're still not on Java 10 or newer, then use StandardCharsets.UTF_8.toString() as charset argument, or when you're still not on Java 7 or newer, then use "UTF-8".


Note that spaces in query parameters are represented by +, not %20, which is legitimately valid. The %20 is usually to be used to represent spaces in URI itself (the part before the URI-query string separator character ?), not in query string (the part after ?).

Also note that there are three encode() methods. One without Charset as second argument and another with String as second argument which throws a checked exception. The one without Charset argument is deprecated. Never use it and always specify the Charset argument. The javadoc even explicitly recommends to use the UTF-8 encoding, as mandated by RFC3986 and W3C.

All other characters are unsafe and are first converted into one or more bytes using some encoding scheme. Then each byte is represented by the 3-character string "%xy", where xy is the two-digit hexadecimal representation of the byte. The recommended encoding scheme to use is UTF-8. However, for compatibility reasons, if an encoding is not specified, then the default encoding of the platform is used.

See also:

  • What every web developer must know about URL encoding
Tuesday, June 1, 2021
 
Kwadz
answered 6 Months ago
46

You could split each of the vars into 2 32-bit values (like a high word and low word), then do a bitwise operation on both pairs.

The script below runs as a Windows .js script. You can replace WScript.Echo() with alert() for Web.

var a = 4294967296;
var b = 4294967296;

var w = 4294967296; // 2^32

var aHI = a / w;
var aLO = a % w;
var bHI = b / w;
var bLO = b % w;

WScript.Echo((aHI & bHI) * w + (aLO & bLO));
Wednesday, June 9, 2021
 
superhero
answered 6 Months ago
93

Although I think the answer from @fge is the right one, as I was using a 3rd party webservice that relied on the encoding outlined in the W3Schools article, I followed the answer from Java equivalent to JavaScript's encodeURIComponent that produces identical output?

public static String encodeURIComponent(String s) {
    String result;

    try {
        result = URLEncoder.encode(s, "UTF-8")
                .replaceAll("\+", "%20")
                .replaceAll("\%21", "!")
                .replaceAll("\%27", "'")
                .replaceAll("\%28", "(")
                .replaceAll("\%29", ")")
                .replaceAll("\%7E", "~");
    } catch (UnsupportedEncodingException e) {
        result = s;
    }

    return result;
}
Sunday, August 1, 2021
 
Pravi
answered 4 Months ago
13

You need to have pre-stored images. Javascript cannot take screenshots and resize the images (for now). Try this: http://snapcasa.com/ . It takes images dynamically for you. All you have to do is to hot link the images :)

The best features when using http://snapcasa.com/:

  1. Images are guaranteed to be most up-to-date

  2. You don't have to store them on your server!

  3. Free plan has lots of credits for you to burn!

Monday, October 11, 2021
 
footy
answered 2 Months ago
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