如何验证 Java 中的字符串是否为有效 URL

How to verify if a String in Java is a valid URL

提问by lacas

How can I check if a string is a URL in Java?

如何检查字符串是否是 Java 中的 URL？

采纳答案by Grodriguez

You can try to create a java.net.URLobject out of it. If it is not a proper URL, a MalformedURLExceptionwill be thrown.

您可以尝试从中创建一个java.net.URL对象。如果它不是正确的 URL，MalformedURLException则会抛出 a。

回答by Bozho

You can use UrlValidatorfrom commons-validator. It will save you from writing code where the logic flow is guided by caching an exception, which is generally considered a bad practice. In this case, however, I think it's fine to do as others suggested, if you move this functionality to an utility method called isValidUrl(..)

您可以UrlValidator从commons-validator 使用。它将避免您编写通过缓存异常来引导逻辑流的代码，这通常被认为是一种不好的做法。但是，在这种情况下，如果您将此功能移动到名为isValidUrl(..)

回答by Esteban Cacavelos

Complementing Bozho answer, to go more practical:

补充Bozho的答案，更实用：

1. Download apache commons packageand uncompress it.
2. Include commons-validator-1.4.0.jar in your java build path.

3. Test it with this sample code (reference):

   //...your imports
   
   import org.apache.commons.validator.routines.*; // Import routines package!
   
   public static void main(String[] args){
   
   // Get an UrlValidator
   UrlValidator defaultValidator = new UrlValidator(); // default schemes
   if (defaultValidator.isValid("http://www.apache.org")) {
       System.out.println("valid");
   }
   if (!defaultValidator.isValid("http//www.oops.com")) {
       System.out.println("INvalid");
   }
   
   // Get an UrlValidator with custom schemes
   String[] customSchemes = { "sftp", "scp", "https" };
   UrlValidator customValidator = new UrlValidator(customSchemes);
   if (!customValidator.isValid("http://www.apache.org")) {
       System.out.println("valid");
   }
   
   // Get an UrlValidator that allows double slashes in the path
   UrlValidator doubleSlashValidator = new UrlValidator(UrlValidator.ALLOW_2_SLASHES);
   if (doubleSlashValidator.isValid("http://www.apache.org//projects")) {
       System.out.println("INvalid");
   }
   

4. Run/Debug

1. 下载 apache commons包并解压。
2. 在您的 java 构建路径中包含 commons-validator-1.4.0.jar。

3. 使用此示例代码（参考）对其进行测试：

   //...your imports
   
   import org.apache.commons.validator.routines.*; // Import routines package!
   
   public static void main(String[] args){
   
   // Get an UrlValidator
   UrlValidator defaultValidator = new UrlValidator(); // default schemes
   if (defaultValidator.isValid("http://www.apache.org")) {
       System.out.println("valid");
   }
   if (!defaultValidator.isValid("http//www.oops.com")) {
       System.out.println("INvalid");
   }
   
   // Get an UrlValidator with custom schemes
   String[] customSchemes = { "sftp", "scp", "https" };
   UrlValidator customValidator = new UrlValidator(customSchemes);
   if (!customValidator.isValid("http://www.apache.org")) {
       System.out.println("valid");
   }
   
   // Get an UrlValidator that allows double slashes in the path
   UrlValidator doubleSlashValidator = new UrlValidator(UrlValidator.ALLOW_2_SLASHES);
   if (doubleSlashValidator.isValid("http://www.apache.org//projects")) {
       System.out.println("INvalid");
   }
   

4. 运行/调试

回答by alijandro

If you program in Android, you could use android.webkit.URLUtilto test.

如果你在Android 中编程，你可以android.webkit.URLUtil用来测试。

URLUtil.isHttpUrl(url)
URLUtil.isHttpsUrl(url)

Hope it would be helpful.

希望它会有所帮助。

回答by Aaron Esau

This function validates a URL, and returns true (valid URL) or false (invalid URL).

此函数验证 URL，并返回 true（有效 URL）或 false（无效 URL）。

public static boolean isURL(String url) {
    try {
        new URL(url);
        return true;
    } catch (Exception e) {
        return false;
    }
}

Be sure to import java.net.URL;

务必 import java.net.URL;

回答by Rafa0809

For Androidjust add this line:

对于Android，只需添加以下行：

boolean isValid = URLUtil.isValidUrl( "your.uri" );

回答by BullyWiiPlaza

Here you go:

干得好：

public static boolean isValidURL(String urlString)
{
    try
    {
        URL url = new URL(urlString);
        url.toURI();
        return true;
    } catch (Exception exception)
    {
        return false;
    }
}

回答by Saurabh Tamrakar

^(https://|http://|ftp://|ftps://)(?!-.)[^\s/$.?#].[^\s]*$

This is a regex to validate URL for protocols http, https, ftp and ftps.

这是一个用于验证 http、https、ftp 和 ftps 协议 URL 的正则表达式。