blocks|key|128108|text|您可以使用java.net.URI-class从字符串中提取主机名。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|128109|下面是一个方法，你可以从一个字符串中提取你的主机名。|128110|public+String+getHostName(String+url)+{
++++URI+uri+=+new+URI(url);
++++String+hostname+=+uri.getHost();
++++//+to+provide+faultproof+result,+check+if+not+null+then+return+only+hostname,+without+www.
++++if+(hostname+!=+null)+{
++++++++return+hostname.startsWith("www.")+?+hostname.substring(4)+:+hostname;
++++}
++++return+hostname;
}|code-block|syntax|javascript|128111|上面给出的是主机名，如果你的主机名是以hostname.com/...或www.hostname.com/...开头的，它将返回'+hostname‘，这是完全正确的。|128112|如果给定的url无效(未定义的主机名)，则返回null。|128113|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/net/URI.html^0|5|C|5|C|0|0|0|0|J|G|10|K|0|5|3|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|6|7|14|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|15|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|O|3|P|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

You can use the <a href="http://docs.oracle.com/javase/7/docs/api/java/net/URI.html" rel="noreferrer"><code>java.net.URI</code></a>-class to extract the hostname from the string.

Here below is a method from which you can extract your hostname from a string.

<pre><code>public String getHostName(String url) {
 URI uri = new URI(url);
 String hostname = uri.getHost();
 // to provide faultproof result, check if not null then return only hostname, without www.
 if (hostname != null) {
 return hostname.startsWith("www.") ? hostname.substring(4) : hostname;
 }
 return hostname;
}
</code></pre>

This above gives you the hostname, and is faultproof if your hostname does start with either <code>hostname.com/...</code> or <code>www.hostname.com/...</code>, which will return with 'hostname'.

If the given <code>url</code> is invalid (undefined hostname), it returns with null.

blocks|key|4634112|text|java.net.URL+aURL;
try+{
++++aURL+=+new+java.net.URL("http://example.com:80/docs/");
++++System.out.println("host+=+"+%2B+aURL.getHost());+//example.com
}+catch+(MalformedURLException+e)+{
++++//+TODO+Auto-generated+catch+block
++++e.printStackTrace();
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4634113|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>java.net.URL aURL;
try {
 aURL = new java.net.URL("http://example.com:80/docs/");
 System.out.println("host = " + aURL.getHost()); //example.com
} catch (MalformedURLException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
}
</code></pre>

blocks|key|4634099|text|java.net.URL+u+=+new+URL("http://hostname:port_no/control/login.jsp");
System.err.println(u.getHost());|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4634100|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>java.net.URL u = new URL("http://hostname:port_no/control/login.jsp");
System.err.println(u.getHost());
</code></pre>

blocks|key|128070|text|如果您想要字符串工作，请尝试以下代码示例，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|128071|String+URL=+"http://hostname:port_no/control/login.jsp";
String+s_URL[]+=+ULR.split("//");
String+s1+=+s_URL[1];
String+s2[]+=+s1.split(":");
String+hostname+=+s2[0];|code-block|syntax|javascript|128072|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you want string work, then try the following code sample,

<pre><code>String URL= "http://hostname:port_no/control/login.jsp";
String s_URL[] = ULR.split("//");
String s1 = s_URL[1];
String s2[] = s1.split(":");
String hostname = s2[0];
</code></pre>

blocks|key|4634226|text|在Java中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4634227|String+hostname+=+url.split("://")[1].split(":")[0];
String+portnumber+=+url.split("://")[1].split(":")[1].split("/")[0];|code-block|syntax|javascript|4634228|希望这能有所帮助。|4634229|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

In Java:

<pre><code>String hostname = url.split("://")[1].split(":")[0];
String portnumber = url.split("://")[1].split(":")[1].split("/")[0];
</code></pre>

Hope this helps.

blocks|key|128181|text|@KarelG的答案是最好的答案，尽管我对某些非标准域名有特定的问题。示例问题包含在下面。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|128182|对于某些“现实世界”的输入值，我必须在URI方案中添加一个检查，以避免某些地址的错误解析。这是更改后的代码。|128183|import+java.net.URI;
import+java.net.*;

public+class+Domain+{
++++public+static+String+getDomainName(String+url)+{
++++++++try+{
++++++++++++URI+uri+=+new+URI(url);
++++++++++++String+domain+=+uri.getHost();
++++++++++++System.out.println("domain:+"+%2B+domain);
++++++++++++if+(uri.getScheme()+!=+null)+{
++++++++++++++++return+domain.startsWith("www.")+?+domain.substring(4)+:+domain;
++++++++++++}+else+{
++++++++++++++++return+uri.getSchemeSpecificPart();
++++++++++++}

++++++++}+catch+(Exception+e)+{
++++++++++++e.printStackTrace();
++++++++++++return+null;
++++++++}
++++}

}|code-block|syntax|javascript|128184|下面是失败的测试用例和值。|128185|Domain.java+javac+Domain.java+java域|128186|import+java.net.URI;
import+java.net.*;
import+java.io.*;

public+class+Domain+{

++++public+static+String+longname+=+"https://www.3dprintingmedia.network/longform/page.html";
++++public+static+String+name+=+"www.3dprintingmedia.network";

++++public+static+void+getDomain(String+url)+{
++++++++try+{
++++++++++++++++++++++++URI+uri+=+new+URI(url);
++++++++++++++++++++++++String+domain+=+uri.getHost();
++++++++++++System.out.println("protocol:+"+%2B+uri.getScheme());
++++++++++++System.out.println("path:+"+%2B+uri.getPath());
++++++++++++++++++++++++System.out.println("name:+"+%2B+name);
++++++++++++++++++++++++System.out.println("domain:+"+%2B+domain);
++++++++++++++++++++++++System.out.println(domain.startsWith("www.")+?+domain.substring(4)+:+domain);
++++++++}+catch+(Exception+e)+{
++++++++++++++++++++++++e.printStackTrace();
++++++++}
+++}

++++public+static+void+main(String[]+args)+{
+++++++System.out.println("Parsing+domain:+"+%2B+name);+
+++++++getDomain(longname);
+++++++getDomain(name);
+++++++System.exit(0);
++++}
}|128187|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|T|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|V|8|@]|9|@]|A|$G|H]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

@KarelG's answer is the best answer, though I had specific issues with certain non-standard domains. The example issue is self contained below. 

For certain "real world" input values, I had to add a check to the URI scheme to avoid mis-parsing of some addresses. This is the changed code. 

<pre><code>import java.net.URI;
import java.net.*;

public class Domain {
 public static String getDomainName(String url) {
 try {
 URI uri = new URI(url);
 String domain = uri.getHost();
 System.out.println("domain: " + domain);
 if (uri.getScheme() != null) {
 return domain.startsWith("www.") ? domain.substring(4) : domain;
 } else {
 return uri.getSchemeSpecificPart();
 }

 } catch (Exception e) {
 e.printStackTrace();
 return null;
 }
 }

}
</code></pre>

Below is the test case and value that was failing.

Domain.java
javac Domain.java
java Domain

<pre><code>import java.net.URI;
import java.net.*;
import java.io.*;

public class Domain {

 public static String longname = "https://www.3dprintingmedia.network/longform/page.html";
 public static String name = "www.3dprintingmedia.network";

 public static void getDomain(String url) {
 try {
 URI uri = new URI(url);
 String domain = uri.getHost();
 System.out.println("protocol: " + uri.getScheme());
 System.out.println("path: " + uri.getPath());
 System.out.println("name: " + name);
 System.out.println("domain: " + domain);
 System.out.println(domain.startsWith("www.") ? domain.substring(4) : domain);
 } catch (Exception e) {
 e.printStackTrace();
 }
 }

 public static void main(String[] args) {
 System.out.println("Parsing domain: " + name); 
 getDomain(longname);
 getDomain(name);
 System.exit(0);
 }
}
</code></pre>

blocks|key|4634331|text|使用正则表达式和组的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4634332|++++String+pattern+=+"(\\w*://)([\\w-_.]%2B)([:\\w\\W]*)";
++++Pattern+r+=+Pattern.compile(pattern);
++++Matcher+m+=+r.matcher(a);
++++if+(m.find())
++++{
++++++++System.out.println(m.group(0));
++++++++System.out.println(m.group(1));
++++++++System.out.println(m.group(2));
++++++++System.out.println(m.group(3));
++++}|code-block|syntax|javascript|4634333|group(2)是主机名。|4634334|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

A solution using Regular expression and group:

<pre><code> String pattern = "(\\w*://)([\\w-_.]+)([:\\w\\W]*)";
 Pattern r = Pattern.compile(pattern);
 Matcher m = r.matcher(a);
 if (m.find())
 {
 System.out.println(m.group(0));
 System.out.println(m.group(1));
 System.out.println(m.group(2));
 System.out.println(m.group(3));
 }
</code></pre>

group(2) is the hostname.

I have a URL like <code>http://hostname:port_no/control/login.jsp</code>.

I have the above url stored in some String.Now, I need to extract <code>hostname</code> from the String.

I am doing like this in my Java code

<pre><code>String domain = url.substring(url.indexOf('/') + 2, url.lastIndexOf(':'));
</code></pre>

I want to know if there is any better way to do the same.

Extract host name/domain name from URL string

Java

我有一个像http://hostname:port_no/control/login.jsp这样的网址。我有上面的网址存储在一些String.Now中，我需要从字符串中提取hostname。我在Java代码中就是这样做的String domain = url.substring(url.indexOf('/') + 2, url.lastIndexOf(':'));我想知道是否有更好的方法来做同样

问从URL字符串中提取主机名/域名
EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问从URL字符串中提取主机名/域名EN

回答 7

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问从URL字符串中提取主机名/域名
EN