how to validate a URL / website name in EditText i

问题:

I want to take input, a URL or just a website name like, www.google.com from EditText in Android and on userclick on the button to submit or when the EditText looses the focus the URL should be validated, like it is in the format "www.anyURL.com"...

How can i do this? is there any inbuilt functionality available in android?

回答1:

Short answer

Use WEB_URL pattern in Patterns Class

 Patterns.WEB_URL.matcher(potentialUrl).matches()

It will return True if URL is valid and false if URL is invalid.

Long answer

As of Android API level 8 there is a WEB_URL pattern. Quoting the source, it "match[es] most part of RFC 3987". If you target a lower API level you could simply copy the pattern from the source and include it in your application. I assume you know how to use patterns and matchers, so I'm not going into more details here.

Also the class URLUtil provides some useful methods, e.g:

• isHttpUrl()
• isValidUrl()

The descriptions of the methods are not very elaborate, therefore you are probably best of looking at the source and figuring out which one fits your purpose best.

As for when to trigger the validation check, there are multiple possibilities: you could use the EditText callback functions

• onFocusChanged(), or
• onTextChanged()

or use a TextWatcher, which I think would be better.

DON'T USE URLUtil to validate the URL as below.

 URLUtil.isValidUrl(url)

because it gives strings like "http://" as valid URL which isn't true

回答2:

/** 
* This is used to check the given URL is valid or not.
* @param url
* @return true if url is valid, false otherwise.
*/
private boolean isValidUrl(String url) {
    Pattern p = Patterns.WEB_URL;
    Matcher m = p.matcher(url.toLowerCase());
    return m.matches();
}

回答3:

URLUtil.isValidUrl will work since it exists since api level 1.

回答4:

Or you could just use good old Regex

Pattern urlRegex = Pattern.compile("((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+@)?[A-Za-z0-9.-]+(:[0-9]+)?|(?:ww‌​w.|[-;:&=\+\$,\w]+@)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%@.\w_]*)#?‌​(?:[\w]*))?)");

I am not saying that Patterns.WEB_URL is bad, it just it makes it easy to test what gets matched and what does not.