你會得到噸假陰性/陽性，如果你依靠Uri.IsWellFormedUriString（），但...
您還可以使用正則表達式和/或字符串比較的組合，以儘量增加你的有效的URL搜索。請注意，我在一些正則表達式會更好的地方使用char比較。我試圖證明你可以做REGEX或直接比較。
更嚴格的REGEX和/或其他邏輯可以產生更好的結果。這不會產生100％的命中率，但它會清除一些不良類型的URL。請注意，正則表達式要求System.Text.RegularExpressions參考：
private List<int> acceptableChars = new List<int>();
private void createListOfAcceptableCharacters()
{
List<int> acceptableChars = new List<int>();
acceptableChars.Add(45);// -
acceptableChars.Add(46);// .
acceptableChars.Add(47);///
for (int a = 97; a < 123; a++)
{// a through z
acceptableChars.Add(a);
}
for (int a = 48; a < 58; a++)
{//0 through 9
acceptableChars.Add(a);
}
}
public string parseURL(string input)
{//you would only do this once in reality
createListOfAcceptableCharacters();
//basic cleanup
input = input.ToLower();
//Regex.Replace would be more elegant here but string.replace works, too
input = input.Replace(".cm", ".com").Replace("htpp","http").Replace("htp", "http").Replace("http.", "http:").Replace("//ww.", "//www.").Replace(":/", "://").Replace(":////", "://").Replace(":///", "://").Replace(" ","");
//check to see if URL is generally valid as-is
bool isValid = isValidURL(input);
if (isValid)
{
return input;
}
//try to salvage a poorly formed URL
bool isSecure = input.Substring(0, 5).IndexOf("https") > -1 ? true : false;
input = input.Replace(" ","").Replace(":","").Replace("https","").Replace("http//", "").Replace("http/", "").Replace("http", "").Replace("http", "").Replace("//","").Replace("www","").Replace("ww","").Replace("cm","com");//again, regex.replace would be more elegant
//clear front end to first period if it exists before space 6
if (input.IndexOf(".") < 7)
{
int period = input.IndexOf(".");
input = input.Substring(period+1);
}
//get the extension
string extension = "";
if (input.Substring(input.Length - 1) == "/")
{
input = input.Substring(0, input.Length - 1);
}
if (input.Substring(input.Length - 4, 1) == ".")
{
//extension is where we expect
extension = input.Substring(input.Length - 3, 3);
input = input.Replace("." + extension, "");
}else
{
//cannot find extension - can't process
return "badURL";
}
string url = "";
//move backwars through path, collecting only acceptable characters (note, this can be done with REGEX as well)
for (int i = input.Length-1; i > -1; i--)
{
string thisChar = input.Substring(i, 1);
if (thisChar == ":")
{
return "http://" + url + "." + extension;
}
int utf = (int)Convert.ToChar(thisChar);
//compare current char to list of acceptable chars
if (acceptableChars.Contains(utf))
{
url = thisChar+url;
}
}
//final cleanup and full path formation
if (url.Substring(0, 1) == ".")
{
url = url.Substring(1);
}
url = isSecure ? "https://" : "http://" + url + "." + extension;
//optional
url = isSecure ? "https://www." : "http://www." + url + "." + extension;
url = url.Replace("::", ":");
//test salvaged url. If reasonable, return else return badURL
if (isValidURL(url))
{
return url;
}else
{
return "badURL";
}
}
private bool isValidURL(string url)
{
bool isValid = Regex.IsMatch(url, @"^((http[s]?:[/][/])?(\w+[\-.])+com|((http[s]?:[/][/])?(\w+[\-.])+com[/]|[.][/])?\w+([/]\w+)*([/]|[.]html|[.]php|[.]gif|[.]jpg|[.]png)?)$");
return isValid;
}
我可能會建議修改解析方法返回而不是「BADURL」中的「固定」的鏈接 - 有時它會解決一個URL，實際上是有效但被RegEx拒絕。您可以嘗試訪問URL並處理任何錯誤，而不是處理「badURL」的返回。
請注意 - 這決不意味着代表最終的工作解決方案。您必須測試並修改多個輸入並相應地清理/優化代碼。它只是作爲示例來演示如何在嘗試清理URL時使用字符串比較和正則表達式。