Java Utililty Methods URL to Host Name

List of utility methods to do URL to Host Name

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Description

The list of methods to do URL to Host Name are organized into topic(s).

Method

String[]getHostAndPortFromUrl(String url)
Parse the string as a URL and extract the host name from it. 
int size = url.length();
char[] url_chars = url.toCharArray();
String scheme = getScheme(url_chars);
if (protocol_ports.get(scheme) == null)
    return null;
int start_pos, end_pos;
int start_hostname, end_hostname;
int start_port, end_port;
...
StringgetHostFromURL(final String urlSpec)
get Host From URL 
if (urlSpec == null) {
    return null;
try {
    final URL url = new URL(urlSpec);
    final String host = url.getHost();
    final int port = url.getPort();
    if (port == -1) {
...
StringgetHostname(String completeUrl)
This method will parse the passed in String which is presumably a complete URL and return the base URL e.g. 
URL baseUrl = null;
try {
    baseUrl = new URL(completeUrl);
    return new URL(baseUrl.getProtocol(), baseUrl.getHost(), baseUrl.getPort(), "").toString();
} catch (MalformedURLException e) {
    throw new RuntimeException("Invalid URL: " + completeUrl);
StringgetHostName(String url)
Gets a host from given URL 
URI uri = new URI(url);
return uri.getHost();
StringgetHostName(String url)
get Host Name 
URI uri = new URI(url);
String hostname = uri.getHost();
if (hostname != null) {
    hostname = hostname.startsWith("www.") ? hostname.substring(4) : hostname;
    hostname = uri.getScheme() + "://" + hostname;
    return hostname;
return hostname;
...
StringgetHostName(String url)
Returns the Host Name as a String, parsed from the given URL. 
String hostName = url.split("://")[1].split(":")[0];
if (hostName.equals("localhost") || hostName.equals("127.0.0.1")) {
    try {
        hostName = InetAddress.getLocalHost().getHostName();
    } catch (UnknownHostException e) {
        throw new AssertionError(e);
return hostName;
StringgetHostName(String url)
get Host Name 
if (url == null || url.length() == 0)
    return "";
url = url.toLowerCase();
if (!url.startsWith("http://") && !url.startsWith("https://") && !url.startsWith("ftp://"))
    throw new MalformedURLException("Unknown schema!");
int doubleslash = url.indexOf("//");
doubleslash += 2;
int end = url.length();
...
StringgetHostname(String urlStr)
returns the hostname of the given URL 
URL url;
try {
    url = new URL(urlStr);
    String hostname = url.getHost();
    return hostname;
} catch (MalformedURLException e) {
    return null;
String[]getHostSegments(URL url)
Partitions of the hostname of the url by "." 
String host = url.getHost();
if (IP_PATTERN.matcher(host).matches())
    return new String[] { host };
return host.split("\\.");