如何验证URL在Java 1.6中是否有效？

2019年8月1日 119次阅读

我的应用程序处理用户手动输入的URL.我发现一些格式错误的URL(如’http：/ not-valid’)导致在打开连接时抛出NullPointerException.正如我从
this Java bug report那里了解到的那样,这个问题是众所周知的,不会被修复.建议使用java.net.URI,这是“更符合RFC 2396的”.

问题是：如何使用URI来解决问题？我唯一能用URI做的就是用它来解析字符串并生成URL.我准备了以下程序：

import java.net.*;

public class Test
{
    public static void main(String[] args)
    {
       try {
           URI uri = URI.create(args[0]);
           Object o = uri.toURL().getContent(); // try to get content
       }
       catch(Throwable e) {
           e.printStackTrace();
       }
    }
}

以下是我的测试结果(使用java 1.6.0_20),与java.net.URL的测试结果差别不大：

sh-3.2$java Test url-not-valid
java.lang.IllegalArgumentException: URI is not absolute
        at java.net.URI.toURL(URI.java:1080)
        at Test.main(Test.java:9)
sh-3.2$java Test http:/url-not-valid
java.lang.NullPointerException
        at sun.net.www.ParseUtil.toURI(ParseUtil.java:261)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:795)
        at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:726)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1049)
        at java.net.URLConnection.getContent(URLConnection.java:688)
        at java.net.URL.getContent(URL.java:1024)
        at Test.main(Test.java:9)
sh-3.2$java Test http:///url-not-valid
java.lang.IllegalArgumentException: protocol = http host = null
        at sun.net.spi.DefaultProxySelector.select(DefaultProxySelector.java:151)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:796)
        at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:726)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1049)
        at java.net.URLConnection.getContent(URLConnection.java:688)
        at java.net.URL.getContent(URL.java:1024)
        at Test.main(Test.java:9)
sh-3.2$java Test http:////url-not-valid
java.lang.NullPointerException
        at sun.net.www.ParseUtil.toURI(ParseUtil.java:261)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:795)
        at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:726)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1049)
        at java.net.URLConnection.getContent(URLConnection.java:688)
        at java.net.URL.getContent(URL.java:1024)
        at Test.main(Test.java:9)

最佳答案 你可以使用appache Validator Commons ..

UrlValidator urlValidator = new UrlValidator();
urlValidator.isValid("http://google.com");

http://commons.apache.org/validator/

http://commons.apache.org/validator/api-1.3.1/

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