网址规范化（或网址规范化）是以一致的方式修改和标准化网址的过程。规范化过程的目标是将 URL 转换为规范化或规范 URL，以便可以确定两个语法上不同的 URL 是否等效。
策略包括添加尾部斜杠，https = > http等。维基百科页面列出了许多。
有一种最喜欢的方法可以在Java中执行此操作吗？也许是一个图书馆（Nutch？），但我是开放的。依赖项越小越少越好。
我现在将手动编写一些代码，并密切关注这个问题。
编辑：我想积极地规范化，如果URL引用相同的内容，则将其计数为相同。例如，我忽略了参数utm_source、utm_medium utm_campaign。例如，如果标题相同，我将忽略子域。
我昨晚发现了这个问题，但没有我正在寻找的答案，所以我做了自己的答案。在这里，以防将来有人想要它：
/**
* - Covert the scheme and host to lowercase (done by java.net.URL)
* - Normalize the path (done by java.net.URI)
* - Add the port number.
* - Remove the fragment (the part after the #).
* - Remove trailing slash.
* - Sort the query string params.
* - Remove some query string params like "utm_*" and "*session*".
*/
public class NormalizeURL
{
public static String normalize(final String taintedURL) throws MalformedURLException
{
final URL url;
try
{
url = new URI(taintedURL).normalize().toURL();
}
catch (URISyntaxException e) {
throw new MalformedURLException(e.getMessage());
}
final String path = url.getPath().replace("/$", "");
final SortedMap<String, String> params = createParameterMap(url.getQuery());
final int port = url.getPort();
final String queryString;
if (params != null)
{
// Some params are only relevant for user tracking, so remove the most commons ones.
for (Iterator<String> i = params.keySet().iterator(); i.hasNext();)
{
final String key = i.next();
if (key.startsWith("utm_") || key.contains("session"))
{
i.remove();
}
}
queryString = "?" + canonicalize(params);
}
else
{
queryString = "";
}
return url.getProtocol() + "://" + url.getHost()
+ (port != -1 && port != 80 ? ":" + port : "")
+ path + queryString;
}
/**
* Takes a query string, separates the constituent name-value pairs, and
* stores them in a SortedMap ordered by lexicographical order.
* @return Null if there is no query string.
*/
private static SortedMap<String, String> createParameterMap(final String queryString)
{
if (queryString == null || queryString.isEmpty())
{
return null;
}
final String[] pairs = queryString.split("&");
final Map<String, String> params = new HashMap<String, String>(pairs.length);
for (final String pair : pairs)
{
if (pair.length() < 1)
{
continue;
}
String[] tokens = pair.split("=", 2);
for (int j = 0; j < tokens.length; j++)
{
try
{
tokens[j] = URLDecoder.decode(tokens[j], "UTF-8");
}
catch (UnsupportedEncodingException ex)
{
ex.printStackTrace();
}
}
switch (tokens.length)
{
case 1:
{
if (pair.charAt(0) == '=')
{
params.put("", tokens[0]);
}
else
{
params.put(tokens[0], "");
}
break;
}
case 2:
{
params.put(tokens[0], tokens[1]);
break;
}
}
}
return new TreeMap<String, String>(params);
}
/**
* Canonicalize the query string.
*
* @param sortedParamMap Parameter name-value pairs in lexicographical order.
* @return Canonical form of query string.
*/
private static String canonicalize(final SortedMap<String, String> sortedParamMap)
{
if (sortedParamMap == null || sortedParamMap.isEmpty())
{
return "";
}
final StringBuffer sb = new StringBuffer(350);
final Iterator<Map.Entry<String, String>> iter = sortedParamMap.entrySet().iterator();
while (iter.hasNext())
{
final Map.Entry<String, String> pair = iter.next();
sb.append(percentEncodeRfc3986(pair.getKey()));
sb.append('=');
sb.append(percentEncodeRfc3986(pair.getValue()));
if (iter.hasNext())
{
sb.append('&');
}
}
return sb.toString();
}
/**
* Percent-encode values according the RFC 3986. The built-in Java URLEncoder does not encode
* according to the RFC, so we make the extra replacements.
*
* @param string Decoded string.
* @return Encoded string per RFC 3986.
*/
private static String percentEncodeRfc3986(final String string)
{
try
{
return URLEncoder.encode(string, "UTF-8").replace("+", "%20").replace("*", "%2A").replace("%7E", "~");
}
catch (UnsupportedEncodingException e)
{
return string;
}
}
}
