I have a page which displays several links () to files which have special characters in their filenames. e.g. "SPRÜCHE.txt".
when i want to browse (GET-request) a link, i get following error:
".../SPRÃœCHE.txt was not found on this server."
But when i replace the special char "Ü" with its ASCII equivalent "%DC", it works fine.
I cannot replace all special chars so ASCII, because there are also other charsets in the filename involved, which cannot be encoded with ASCII (e.g. chinese)
I already tried it with lots of encoding methods, like URLEncoder.encode("","UTF-8"); but this returns me a unicode representation which cannot be parsed correctly in the url ("SPR%c3%9cCHE.txt cannot be found...")
is there a function, which makes a UTF-8 hyperlink / url web-safe?
I use tomcat 7
Related
It is clearly stated in W3Schools that
URLs can only be sent over the Internet using the ASCII character-set.
Why does URL encoding exist for ASCII characters like a , b , c when it can be sent over the internet without any URL encoding ???
Eg: Why encode 'a' when it can send over as 'a'
What are the possible reasons to encode ASCII characters ?? The only reason i can think of are hackers who are trying to make their URL as unreadable as possible to carry out XSS attacks
STD 66, Percent-Encoding:
A percent-encoding mechanism is used to represent a data octet in a component when that octet's corresponding character is outside the allowed set or is being used as a delimiter of, or within, the component.
So percent-encoding is a kind of escape mechanism: Some characters have a special meaning in URI components (→ they are reserved). If you want to use such a character without its special meaning, you percent-encode it.
Unreserved characters (like a, b, c, …) can always be used directly, but it’s also allowed to percent-encode them. Such URIs would be equivalent:
URIs that differ in the replacement of an unreserved character with its corresponding percent-encoded US-ASCII octet are equivalent: they identify the same resource.
Why it’s allowed to percent-encode unreserved characters in the first place? The obsolete RFC 2396 contains (bold by me):
Unreserved characters can be escaped without changing the semantics of the URI, but this should not be done unless the URI is being used in a context that does not allow the unescaped character to appear.
I can’t think of an example for such a "context", but this sentence suggests that there may be some.
Also, maybe some people/implementations like to simply percent-encode everything (except for delimiters etc.), so they don’t have to check if/which characters would need percent-encoding in the corresponding component.
URL encoding exists for the full range of ASCII because it was easier to define an encoding that works for all characters than to define one that only works for the set of characters with special meanings.
URL encoding allows for characters that have special meaning in a URL to be included in a segment, without their special meaning. There are many examples, but the most common ones to require encoding include " ", "?", "=" and "&"
URL encoding was designed so it can encode any ASCII character.
While = is encoded as %3d, ? is encoded as %3f and & is encoded as %26, it makes sense for a to be encoded as %61 and b to be encoded as %62, as the hex number after the % represents the ASCII code of the character.
I have imported images to my own server. One of the many filenames has %20 in them, e.g. 50128%202789%20001V%20500.jpg. However the browser sees it as 50128 2789 001V 500.jpg, so it won't display the image.
What solution can I use, to display the image properly?
"%20" is a percent-encoding for a space, and has special meaning in a URL. Basically, you can't use spaces in a URI or URL, and have to replace them with a code to comply with the rules. Things that read URLs (the server for example) translate them back.
Unfortunately, that means if you have a filename containing this sequence, it will be mistaken for a percent-encoded space, as you're seeing.
The solution is to also percent-encode the '%'. The percent-encoding for a '%' character is "%25".
In your example, the name "50128%202789%20001V%20500.jpg" has to be encoded to "50128%25202789%2520001V%2520500.jpg" so that those '%' characters are not mistaken for spaces.
There are of course other things that get encoded. The rules are defined in the URI specification.
I have the following string, read from an XML attribute:
"OnTrak 4-3/4”, 6-3/4”, 8-1/4” / MPR"
In my C# application it shows up nicely formatted like this
"OnTrak 4-3/4”, 6-3/4”, 8-1/4” / MPR"
This is the form I see in the debugger, a combobox, or on this forum (if I don't indent to specify code).
What I want to do is specify the same string as a C# variable and have it show up nicely formatted when the application runs. Unfortunately, all I get is the string as I literally typed it.
I have tried to play around with converting the encoding from ASCII to UTF8 with no luck. How can I get this special character properly formatted, and where can I find a list of these symbols?
Those are called XML entities. Use HttpUtility.HtmlDecode to decode them back to plain text like you would like. Credit goes to C#, function to replace all html special characters with normal text characters for how to convert entities in C#
Note that converting from ASCII to UTF8 (and Unicode etc.) is called changing the character set and is usually done when specific characters are in the string. For instance if you strings contained Chinese characters you couldn't use ASCII. In this simple case you shouldn't need to convert character sets because C# strings are Unicode character set by default and XML entities are Unicode based (I believe).
I need to replace the characters å, ä, ö to browser friendly chars. For example ä should become %E4.
I tried weirdString = Uri.EscapeUriString(weirdString);
But it doesnt convert the åäö to the right sign. Help please?
Edit: Tried this:
ASCIIEncoding ascii = new ASCIIEncoding();
byte[] asciicharacters = Encoding.UTF8.GetBytes("vägen");
byte[] asciiArray = Encoding.Convert(Encoding.UTF8, Encoding.ASCII, asciicharacters);
string finalString = ascii.GetString(asciiArray);
string fixedAddrString = HttpUtility.HtmlEncode(finalString);
If you need the characters to display on the page and not part of a URL, you should use Server.HtmlEncode.
var encodedString = Server.HtmlEncode(myString);
HTML encoding makes sure that text is displayed correctly in the browser and not interpreted by the browser as HTML. For example, if a text string contains a less than sign (<) or greater than sign (>), the browser would interpret these characters as the opening or closing bracket of an HTML tag. When the characters are HTML encoded, they are converted to the strings < and >, which causes the browser to display the less than sign and greater than sign correctly.
Update:
Since you are using UTF-8, these characters are escaped to UTF-8, not ASCII.
You need to convert the string from UTF-8 to ASCII, using the Encoding classes before you try to escape them. That is, if you do want the ASCII values to come up.
See here.
Try HttpUtility.HtmlDecode.
If this doesent working too you can do a simple string.Replace for this chars.
When I put cyrillic symbols in address bar like this:
http://ru2.php.net/manual-lookup.php?pattern=привет
it switches to
http://ru2.php.net/manual-lookup.php?pattern=%EF%F0%E8%E2%E5%F2
What does that characters -- %EF%F0%E8%E2%E5%F2 -- mean? And why is it happening?
The characters are getting URL encoded. A URL may only contain a subset of ASCII characters, so anything outside plain alphanumeric and some special characters must be URL encoded.
Some browsers display non-ASCII characters as human readable characters, but that's entirely up to them. In protocols, URLs are always URL encoded.