blocks|key|220883|text|检查您的连接。在我的计算机上，这两个IP都打印为可达：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|220884|220885|向127.0.0.1发送Ping请求|blockquote|220886|220887|主机可访问|220888|向173.194.32.38发送Ping请求|220889|220890|220891|编辑：|220892|您可以尝试修改代码以使用getByAddress()来获取地址：|220893|public+static+void+main(String[]+args)+throws+UnknownHostException,+IOException+{
++++InetAddress+inet;

++++inet+=+InetAddress.getByAddress(new+byte[]+{+127,+0,+0,+1+});
++++System.out.println("Sending+Ping+Request+to+"+%2B+inet);
++++System.out.println(inet.isReachable(5000)+?+"Host+is+reachable"+:+"Host+is+NOT+reachable");

++++inet+=+InetAddress.getByAddress(new+byte[]+{+(byte)+173,+(byte)+194,+32,+38+});
++++System.out.println("Sending+Ping+Request+to+"+%2B+inet);
++++System.out.println(inet.isReachable(5000)+?+"Host+is+reachable"+:+"Host+is+NOT+reachable");
}|code-block|syntax|javascript|220894|getByName()方法可能会尝试某种反向DNS查找，这在您的机器上可能是不可能的，getByAddress()可能会绕过它。|220895|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|10|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|11|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|12|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|13|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|14|8|@]|9|@]|A|$]]|$1|K|3|H|5|6|7|15|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|S|7|19|8|@]|9|@]|A|$T|U]]|$1|V|3|W|5|6|7|1A|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Y|$]]

Check your connectivity. On my Computer this prints REACHABLE for both IP's:

<blockquote>
 Sending Ping Request to 127.0.0.1 
 Host is reachable 
 Sending Ping Request to 173.194.32.38 
 Host is reachable
</blockquote>

EDIT:

You could try modifying the code to use getByAddress() to obtain the address:

<pre><code>public static void main(String[] args) throws UnknownHostException, IOException {
 InetAddress inet;

 inet = InetAddress.getByAddress(new byte[] { 127, 0, 0, 1 });
 System.out.println("Sending Ping Request to " + inet);
 System.out.println(inet.isReachable(5000) ? "Host is reachable" : "Host is NOT reachable");

 inet = InetAddress.getByAddress(new byte[] { (byte) 173, (byte) 194, 32, 38 });
 System.out.println("Sending Ping Request to " + inet);
 System.out.println(inet.isReachable(5000) ? "Host is reachable" : "Host is NOT reachable");
}
</code></pre>

The getByName() methods may attempt some kind of reverse DNS lookup which may not be possible on your machine, getByAddress() might bypass that.

blocks|key|3084236|text|您不能简单地在Java中ping，因为它依赖于ICMP，遗憾的是Java不支持ICMP|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084237|http://mindprod.com/jgloss/ping.html|offset|length|3084238|改用套接字|3084239|希望能有所帮助|3084240|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|10|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@$D|S|E|T|1|U]]|A|$]]|$1|F|3|G|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|C]]]]

You can not simply ping in Java as it relies on ICMP, which is sadly not supported in Java 

<a href="http://mindprod.com/jgloss/ping.html">http://mindprod.com/jgloss/ping.html</a>

Use sockets instead

Hope it helps

blocks|key|3084266|text|javadoc中的InetAddress.isReachable()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3084267|如果可以获得权限，典型的实现将使用|3084268|回显请求，否则将尝试在目标主机的端口7(回显)上建立连接。|blockquote|3084269|3084270|3084271|选项1+(ICMP)通常需要管理(root)权限。|3084272|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.oracle.com/javase/7/docs/api/java/net/InetAddress.html#isReachable%2528int%2529^0|9|P|0|7|0|0|0|0|0|0|G|6|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$]]|$1|K|3|-4|5|6|7|14|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|15|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|19|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

<code>InetAddress.isReachable()</code> according to <a href="http://docs.oracle.com/javase/7/docs/api/java/net/InetAddress.html#isReachable%28int%29">javadoc</a>:

<blockquote>
 ".. A typical implementation will use ICMP ECHO REQUESTs if the
 privilege can be obtained, otherwise it will try to establish a TCP
 connection on port 7 (Echo) of the destination host..".
</blockquote>

Option #1 (ICMP) usually requires administrative <code>(root)</code> rights.

blocks|key|3084286|text|它肯定会起作用的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084287|import+java.io.*;
import+java.util.*;

public+class+JavaPingExampleProgram
{

++public+static+void+main(String+args[])+
++throws+IOException
++{
++++//+create+the+ping+command+as+a+list+of+strings
++++JavaPingExampleProgram+ping+=+new+JavaPingExampleProgram();
++++List<String>+commands+=+new+ArrayList<String>();
++++commands.add("ping");
++++commands.add("-c");
++++commands.add("5");
++++commands.add("74.125.236.73");
++++ping.doCommand(commands);
++}

++public+void+doCommand(List<String>+command)+
++throws+IOException
++{
++++String+s+=+null;

++++ProcessBuilder+pb+=+new+ProcessBuilder(command);
++++Process+process+=+pb.start();

++++BufferedReader+stdInput+=+new+BufferedReader(new+InputStreamReader(process.getInputStream()));
++++BufferedReader+stdError+=+new+BufferedReader(new+InputStreamReader(process.getErrorStream()));

++++//+read+the+output+from+the+command
++++System.out.println("Here+is+the+standard+output+of+the+command:\n");
++++while+((s+=+stdInput.readLine())+!=+null)
++++{
++++++System.out.println(s);
++++}

++++//+read+any+errors+from+the+attempted+command
++++System.out.println("Here+is+the+standard+error+of+the+command+(if+any):\n");
++++while+((s+=+stdError.readLine())+!=+null)
++++{
++++++System.out.println(s);
++++}
++}

}|code-block|syntax|javascript|3084288|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|$]]

It will work for sure 

<pre><code>import java.io.*;
import java.util.*;

public class JavaPingExampleProgram
{

 public static void main(String args[]) 
 throws IOException
 {
 // create the ping command as a list of strings
 JavaPingExampleProgram ping = new JavaPingExampleProgram();
 List&lt;String&gt; commands = new ArrayList&lt;String&gt;();
 commands.add("ping");
 commands.add("-c");
 commands.add("5");
 commands.add("74.125.236.73");
 ping.doCommand(commands);
 }

 public void doCommand(List&lt;String&gt; command) 
 throws IOException
 {
 String s = null;

 ProcessBuilder pb = new ProcessBuilder(command);
 Process process = pb.start();

 BufferedReader stdInput = new BufferedReader(new InputStreamReader(process.getInputStream()));
 BufferedReader stdError = new BufferedReader(new InputStreamReader(process.getErrorStream()));

 // read the output from the command
 System.out.println("Here is the standard output of the command:\n");
 while ((s = stdInput.readLine()) != null)
 {
 System.out.println(s);
 }

 // read any errors from the attempted command
 System.out.println("Here is the standard error of the command (if any):\n");
 while ((s = stdError.readLine()) != null)
 {
 System.out.println(s);
 }
 }

}
</code></pre>

blocks|key|2870449|text|您可以使用此方法ping+Windows和其他平台上的主机：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2870450|private+static+boolean+ping(String+host)+throws+IOException,+InterruptedException+{
++++boolean+isWindows+=+System.getProperty("os.name").toLowerCase().contains("win");

++++ProcessBuilder+processBuilder+=+new+ProcessBuilder("ping",+isWindows?+"-n"+:+"-c",+"1",+host);
++++Process+proc+=+processBuilder.start();

++++int+returnVal+=+proc.waitFor();
++++return+returnVal+==+0;
}|code-block|syntax|javascript|2870451|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|$]]

You can use this method to ping hosts on Windows and other platforms: 

<pre><code>private static boolean ping(String host) throws IOException, InterruptedException {
 boolean isWindows = System.getProperty("os.name").toLowerCase().contains("win");

 ProcessBuilder processBuilder = new ProcessBuilder("ping", isWindows? "-n" : "-c", "1", host);
 Process proc = processBuilder.start();

 int returnVal = proc.waitFor();
 return returnVal == 0;
}
</code></pre>

blocks|key|3084311|text|在使用oracle-jdk的linux上，OP提交的代码在不是root时使用端口7，在root时使用ICMP。当按照文档指定的根用户身份运行时，它会执行真正的ICMP回显请求。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084312|如果您在MS机器上运行此应用程序，则可能必须以管理员身份运行该应用程序才能获得ICMP行为。|3084313|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

On linux with oracle-jdk the code the OP submitted uses port 7 when not root and ICMP when root. It does do a real ICMP echo request when run as root as the documentation specifies.

If you running this on a MS machine you may have to run the app as administrator to get the ICMP behaviour.

blocks|key|221182|text|我知道前面的条目已经回答了这个问题，但是对于任何其他遇到这个问题的人，我确实找到了一种方法，它不需要在windows中使用"ping“进程，然后再清理输出。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|221183|我所做的是使用JNA调用Window的IP帮助器库来执行ICMP回显|221184|请参阅my+own+answer+to+my+own+similar+issue|offset|length|221185|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/19383757/2821263^0|0|0|3|11|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@$F|S|G|T|1|U]]|A|$]]|$1|H|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]]]

I know this has been answered with previous entries, but for anyone else that comes to this question, I did find a way that did not require having use the "ping" process in windows and then scrubbing the output.

What I did was use JNA to invoke Window's IP helper library to do an ICMP echo

See <a href="https://stackoverflow.com/a/19383757/2821263">my own answer to my own similar issue</a>

blocks|key|3084329|text|我认为这段代码会对你有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084330|public+class+PingExample+{
++++public+static+void+main(String[]+args){
++++++++try{
++++++++++++InetAddress+address+=+InetAddress.getByName("192.168.1.103");
++++++++++++boolean+reachable+=+address.isReachable(10000);

++++++++++++System.out.println("Is+host+reachable?+"+%2B+reachable);
++++++++}+catch+(Exception+e){
++++++++++++e.printStackTrace();
++++++++}
++++}
}|code-block|syntax|javascript|3084331|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|$]]

I think this code will help you:

<pre><code>public class PingExample {
 public static void main(String[] args){
 try{
 InetAddress address = InetAddress.getByName("192.168.1.103");
 boolean reachable = address.isReachable(10000);

 System.out.println("Is host reachable? " + reachable);
 } catch (Exception e){
 e.printStackTrace();
 }
 }
}
</code></pre>

blocks|key|2870538|text|这只是别人给出的一个补充，即使它们工作得很好，但在某些情况下，如果互联网速度很慢或存在一些未知的网络问题，一些代码将不能工作，但下面提到的代码创建了一个进程，它充当windows的命令行+(cmd+ping)。它在所有情况下都适用于我，尝试和测试。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2870539|代码:-|2870540|public+class+JavaPingApp+{

public+static+void+runSystemCommand(String+command)+{

++++try+{
++++++++Process+p+=+Runtime.getRuntime().exec(command);
++++++++BufferedReader+inputStream+=+new+BufferedReader(
++++++++++++++++new+InputStreamReader(p.getInputStream()));

++++++++String+s+=+"";
++++++++//+reading+output+stream+of+the+command
++++++++while+((s+=+inputStream.readLine())+!=+null)+{
++++++++++++System.out.println(s);
++++++++}

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

public+static+void+main(String[]+args)+{

++++String+ip+=+"stackoverflow.com";+//Any+IP+Address+on+your+network+/+Web
++++runSystemCommand("ping+"+%2B+ip);
}
}|code-block|syntax|javascript|2870541|希望它能帮上忙，干杯！|2870542|entityMap^0|2L|V|0|0|4|0|0|0|B|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

Just an addition to what others have given, even though they work well but in some cases if internet is slow or some unknown network problem exists, some of the codes won't work (<code>isReachable()</code>). But this code mentioned below creates a process which acts as a command line ping (cmd ping) to windows. It works for me in all cases, tried and tested.

Code :-

<pre><code>public class JavaPingApp {

public static void runSystemCommand(String command) {

 try {
 Process p = Runtime.getRuntime().exec(command);
 BufferedReader inputStream = new BufferedReader(
 new InputStreamReader(p.getInputStream()));

 String s = "";
 // reading output stream of the command
 while ((s = inputStream.readLine()) != null) {
 System.out.println(s);
 }

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

public static void main(String[] args) {

 String ip = "stackoverflow.com"; //Any IP Address on your network / Web
 runSystemCommand("ping " + ip);
}
}
</code></pre>

Hope it helps, Cheers!!!

blocks|key|3084437|text|以下是一种在Windows和Unix系统上可以pinging通Java中的IP地址的方法：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3084438|import+org.apache.commons.lang3.SystemUtils;

import+java.io.BufferedReader;
import+java.io.IOException;
import+java.io.InputStreamReader;
import+java.util.ArrayList;
import+java.util.List;

public+class+CommandLine
{
++++/**
+++++*+@param+ipAddress+The+internet+protocol+address+to+ping
+++++*+@return+True+if+the+address+is+responsive,+false+otherwise
+++++*/
++++public+static+boolean+isReachable(String+ipAddress)+throws+IOException
++++{
++++++++List<String>+command+=+buildCommand(ipAddress);
++++++++ProcessBuilder+processBuilder+=+new+ProcessBuilder(command);
++++++++Process+process+=+processBuilder.start();

++++++++try+(BufferedReader+standardOutput+=+new+BufferedReader(new+InputStreamReader(process.getInputStream())))
++++++++{
++++++++++++String+outputLine;

++++++++++++while+((outputLine+=+standardOutput.readLine())+!=+null)
++++++++++++{
++++++++++++++++//+Picks+up+Windows+and+Unix+unreachable+hosts
++++++++++++++++if+(outputLine.toLowerCase().contains("destination+host+unreachable"))
++++++++++++++++{
++++++++++++++++++++return+false;
++++++++++++++++}
++++++++++++}
++++++++}

++++++++return+true;
++++}

++++private+static+List<String>+buildCommand(String+ipAddress)
++++{
++++++++List<String>+command+=+new+ArrayList<>();
++++++++command.add("ping");

++++++++if+(SystemUtils.IS_OS_WINDOWS)
++++++++{
++++++++++++command.add("-n");
++++++++}+else+if+(SystemUtils.IS_OS_UNIX)
++++++++{
++++++++++++command.add("-c");
++++++++}+else
++++++++{
++++++++++++throw+new+UnsupportedOperationException("Unsupported+operating+system");
++++++++}

++++++++command.add("1");
++++++++command.add(ipAddress);

++++++++return+command;
++++}
}|code-block|syntax|javascript|3084439|确保将Apache+Commons+Lang添加到您的依赖项中。|3084440|entityMap|0|LINK|mutability|MUTABLE|url|https://mvnrepository.com/artifact/org.apache.commons/commons-lang3^0|6|7|E|4|V|4|0|0|3|J|3|J|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]]|E|$]]|$1|M|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

Here is a method for pinging an IP address in <code>Java</code> that should work on <code>Windows</code> and <code>Unix</code> systems:

<pre><code>import org.apache.commons.lang3.SystemUtils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class CommandLine
{
 /**
 * @param ipAddress The internet protocol address to ping
 * @return True if the address is responsive, false otherwise
 */
 public static boolean isReachable(String ipAddress) throws IOException
 {
 List&lt;String&gt; command = buildCommand(ipAddress);
 ProcessBuilder processBuilder = new ProcessBuilder(command);
 Process process = processBuilder.start();

 try (BufferedReader standardOutput = new BufferedReader(new InputStreamReader(process.getInputStream())))
 {
 String outputLine;

 while ((outputLine = standardOutput.readLine()) != null)
 {
 // Picks up Windows and Unix unreachable hosts
 if (outputLine.toLowerCase().contains("destination host unreachable"))
 {
 return false;
 }
 }
 }

 return true;
 }

 private static List&lt;String&gt; buildCommand(String ipAddress)
 {
 List&lt;String&gt; command = new ArrayList&lt;&gt;();
 command.add("ping");

 if (SystemUtils.IS_OS_WINDOWS)
 {
 command.add("-n");
 } else if (SystemUtils.IS_OS_UNIX)
 {
 command.add("-c");
 } else
 {
 throw new UnsupportedOperationException("Unsupported operating system");
 }

 command.add("1");
 command.add(ipAddress);

 return command;
 }
}
</code></pre>

Make sure to add <a href="https://mvnrepository.com/artifact/org.apache.commons/commons-lang3" rel="nofollow noreferrer"><code>Apache Commons Lang</code></a> to your dependencies.

blocks|key|2870575|text|这应该是可行的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2870576|import+java.io.BufferedReader;
import+java.io.InputStreamReader;

public+class+Pinger+{

private+static+String+keyWordTolookFor+=+"average";

public+Pinger()+{
++++//+TODO+Auto-generated+constructor+stub
}


+public+static+void+main(String[]+args)+{
+//Test+the+ping+method+on+Windows.
+System.out.println(ping("192.168.0.1"));+}


public+String+ping(String+IP)+{
++++try+{
++++++++String+line;
++++++++Process+p+=+Runtime.getRuntime().exec("ping+-n+1+"+%2B+IP);
++++++++BufferedReader+input+=+new+BufferedReader(new+InputStreamReader(p.getInputStream()));
++++++++while+(((line+=+input.readLine())+!=+null))+{

++++++++++++if+(line.toLowerCase().indexOf(keyWordTolookFor.toLowerCase())+!=+-1)+{

++++++++++++++++String+delims+=+"[+]%2B";
++++++++++++++++String[]+tokens+=+line.split(delims);
++++++++++++++++return+tokens[tokens.length+-+1];
++++++++++++}+
++++++++}

++++++++input.close();
++++}+catch+(Exception+err)+{
++++++++err.printStackTrace();
++++}
++++return+"Offline";
}|code-block|syntax|javascript|2870577|}|2870578|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|$]]

This should work:

<pre><code>import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Pinger {

private static String keyWordTolookFor = "average";

public Pinger() {
 // TODO Auto-generated constructor stub
}


 public static void main(String[] args) {
 //Test the ping method on Windows.
 System.out.println(ping("192.168.0.1")); }


public String ping(String IP) {
 try {
 String line;
 Process p = Runtime.getRuntime().exec("ping -n 1 " + IP);
 BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
 while (((line = input.readLine()) != null)) {

 if (line.toLowerCase().indexOf(keyWordTolookFor.toLowerCase()) != -1) {

 String delims = "[ ]+";
 String[] tokens = line.split(delims);
 return tokens[tokens.length - 1];
 } 
 }

 input.close();
 } catch (Exception err) {
 err.printStackTrace();
 }
 return "Offline";
}
</code></pre>

}

blocks|key|217842|text|InetAddress并不总是返回正确的值。对于本地主机，它是成功的，但对于其他主机，这表明该主机是无法访问的。尝试使用下面给出的ping命令。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|217843|try+{
++++String+cmd+=+"cmd+/C+ping+-n+1+"+%2B+ip+%2B+"+%7C+find+\"TTL\"";++++++++
++++Process+myProcess+=+Runtime.getRuntime().exec(cmd);
++++myProcess.waitFor();

++++if(myProcess.exitValue()+==+0)+{

++++return+true;
++++}
++++else+{
++++++++return+false;
++++}
}
catch+(Exception+e)+{
++++e.printStackTrace();
++++return+false;
}|code-block|syntax|javascript|217844|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|$]]

InetAddress is not always return correct value. It is successful in case of Local Host but for other hosts this shows that the host is unreachable. Try using ping command as given below.

<pre><code>try {
 String cmd = "cmd /C ping -n 1 " + ip + " | find \"TTL\""; 
 Process myProcess = Runtime.getRuntime().exec(cmd);
 myProcess.waitFor();

 if(myProcess.exitValue() == 0) {

 return true;
 }
 else {
 return false;
 }
}
catch (Exception e) {
 e.printStackTrace();
 return false;
}
</code></pre>

blocks|key|221242|text|尽管这并不依赖于ICMP+on+Windows，但是这个实现在新的Duration+API中工作得很好|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|221243|public+static+Duration+ping(String+host)+{
++++Instant+startTime+=+Instant.now();
++++try+{
++++++++InetAddress+address+=+InetAddress.getByName(host);
++++++++if+(address.isReachable(1000))+{
++++++++++++return+Duration.between(startTime,+Instant.now());
++++++++}
++++}+catch+(IOException+e)+{
++++++++//+Host+not+available,+nothing+to+do+here
++++}
++++return+Duration.ofDays(1);
}|code-block|syntax|javascript|221244|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html^0|X|C|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Even though this does not rely on ICMP on Windows, this implementation works pretty well with the new <a href="https://docs.oracle.com/javase/8/docs/api/java/time/Duration.html" rel="nofollow noreferrer">Duration API</a>

<pre><code>public static Duration ping(String host) {
 Instant startTime = Instant.now();
 try {
 InetAddress address = InetAddress.getByName(host);
 if (address.isReachable(1000)) {
 return Duration.between(startTime, Instant.now());
 }
 } catch (IOException e) {
 // Host not available, nothing to do here
 }
 return Duration.ofDays(1);
}
</code></pre>

blocks|key|3084565|text|我尝试了几个选项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084566|3084567|Java+InetAddress|ordered-list-item|3084568|3084569|InetAddress.getByName(ipAddress)，windows上的网络在尝试了几次后开始运行不正常|offset|length|style|CODE|3084570|3084571|Java+HttpURLConnection|3084572|3084573|URL+siteURL+=新URL(url)；connection+=+(HttpURLConnection)+siteURL.openConnection()；connection.setRequestMethod("GET")；connection.setConnectTimeout(pingTime)；connection.connect()；code+=+connection.getResponseCode()；if+(代码代码200)+{+==+=+200；}。|3084574|这是可靠的，但有点慢。|3084575|3084576|Windows批处理文件|3084577|3084578|我最终决定在我的windows机器上创建一个包含以下内容的批处理文件：ping.exe+-n+%25echoCount%25+%25pingIp%25，然后在我的java代码中调用.bat文件，使用|3084579|public+int+pingBat(Network+network)+{
ProcessBuilder+pb+=+new+ProcessBuilder(pingBatLocation);
Map<String,+String>+env+=+pb.environment();

env.put(
++++++++"echoCount",+noOfPings+%2B+"");
env.put(
++++++++"pingIp",+pingIp);
File+outputFile+=+new+File(outputFileLocation);
File+errorFile+=+new+File(errorFileLocation);

pb.redirectOutput(outputFile);

pb.redirectError(errorFile);

Process+process;

try+{
++++process+=+pb.start();
++++process.waitFor();
++++String+finalOutput+=+printFile(outputFile);
++++if+(finalOutput+!=+null+&&+finalOutput.toLowerCase().contains("reply+from"))+{
++++++++return+200;
++++}+else+{
++++++++return+202;
++++}
}+catch+(IOException+e)+{
++++log.debug(e.getMessage());
++++return+203;
}+catch+(InterruptedException+e)+{
++++log.debug(e.getMessage());
++++return+204;
}|code-block|syntax|javascript|3084580|}|3084581|事实证明，这是最快、最可靠的方法|3084582|entityMap^0|0|0|0|0|0|W|0|0|0|0|0|0|0|0|0|Z|W|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1D|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|1F|8|@$I|1G|J|1H|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|N|3|O|5|E|7|1J|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1L|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1M|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]|$1|V|3|W|5|E|7|1O|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1Q|8|@$I|1R|J|1S|K|L]]|9|@]|A|$]]|$1|10|3|11|5|12|7|1T|8|@]|9|@]|A|$13|14]]|$1|15|3|16|5|6|7|1U|8|@]|9|@]|A|$]]|$1|17|3|18|5|6|7|1V|8|@]|9|@]|A|$]]|$1|19|3|-4|5|6|7|1W|8|@]|9|@]|A|$]]]|1A|$]]

I tried a couple of options:

<ol>
<li>Java InetAddress</li>
</ol>

<code>InetAddress.getByName(ipAddress)</code>, the network on windows started misbehaving after trying a couple of times

<ol start="2">
<li>Java HttpURLConnection

<pre><code> URL siteURL = new URL(url);
 connection = (HttpURLConnection) siteURL.openConnection();
 connection.setRequestMethod("GET");
 connection.setConnectTimeout(pingTime);
 connection.connect();

 code = connection.getResponseCode();
 if (code == 200) {
 code = 200;
 }.
</code></pre></li>
</ol>

This was reliable but a bit slow

<ol start="3">
<li>Windows Batch File</li>
</ol>

I finally settled to creating a batch file on my windows machine with the following contents: <code>ping.exe -n %echoCount% %pingIp%</code>
Then I called the .bat file in my java code using 

<pre><code>public int pingBat(Network network) {
ProcessBuilder pb = new ProcessBuilder(pingBatLocation);
Map&lt;String, String&gt; env = pb.environment();

env.put(
 "echoCount", noOfPings + "");
env.put(
 "pingIp", pingIp);
File outputFile = new File(outputFileLocation);
File errorFile = new File(errorFileLocation);

pb.redirectOutput(outputFile);

pb.redirectError(errorFile);

Process process;

try {
 process = pb.start();
 process.waitFor();
 String finalOutput = printFile(outputFile);
 if (finalOutput != null &amp;&amp; finalOutput.toLowerCase().contains("reply from")) {
 return 200;
 } else {
 return 202;
 }
} catch (IOException e) {
 log.debug(e.getMessage());
 return 203;
} catch (InterruptedException e) {
 log.debug(e.getMessage());
 return 204;
}
</code></pre>

}

This proved to be the fastest and most reliable way

blocks|key|3084624|text|简短的建议:不要使用isReachable()，调用系统ping，如上面的一些答案所建议的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084625|冗长的解释：|3084626|3084627|ping使用ICMP网络协议。要使用ICMP，原始套接字是指操作系统不允许needed|unordered-list-item|3084628|standard用户使用原始套接字|3084629|以下内容适用于fedora+30+linux，windows系统应类似|3084630|如果java以根用户身份运行，isReachable()实际上发送ICMP+ping请求|3084631|如果java不以根用户身份运行，isReachable()尝试连接到TCP端口7，称为回应端口。此服务通常不再使用，尝试使用它可能会对连接请求的任何类型的应答产生不正确的结果，并且拒绝(TCP+flag+RST)会从isReachable()|3084632|some防火墙|3084633|+RST为任何未显式打开的端口生成'true‘。如果发生这种情况，您将得到的主机甚至没有exist|3084634|further尝试分配必要的能力到一个java+process:|3084635|setcap套接字java可执行文件(分配权限使用原始的sockets)|3084636|test:+getcap+java可执行文件‘TCP’(能力是assigned)|3084637|the运行java仍然发送一个isReachable请求到端口7|3084638|检查运行的java进程与getpcaps+pid显示运行的java进程不具有原始套接字能力)的isReachable()+==+cap_net_raw%2Beip+->+'cap_net_raw%2Beip‘。显然，我的setcap已经被某些安全机制|3084639|覆盖了，因为安全需求不断增加，这可能会变得更加受限，除非s.b.实现一个异常，特别是对于ping+(但到目前为止在网络上找不到)|3084640|3084641|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|E|3|F|5|G|7|1B|8|@]|9|@]|A|$]]|$1|H|3|I|5|G|7|1C|8|@]|9|@]|A|$]]|$1|J|3|K|5|G|7|1D|8|@]|9|@]|A|$]]|$1|L|3|M|5|G|7|1E|8|@]|9|@]|A|$]]|$1|N|3|O|5|G|7|1F|8|@]|9|@]|A|$]]|$1|P|3|Q|5|G|7|1G|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1H|8|@]|9|@]|A|$]]|$1|T|3|U|5|G|7|1I|8|@]|9|@]|A|$]]|$1|V|3|W|5|G|7|1J|8|@]|9|@]|A|$]]|$1|X|3|Y|5|G|7|1K|8|@]|9|@]|A|$]]|$1|Z|3|10|5|G|7|1L|8|@]|9|@]|A|$]]|$1|11|3|12|5|G|7|1M|8|@]|9|@]|A|$]]|$1|13|3|14|5|G|7|1N|8|@]|9|@]|A|$]]|$1|15|3|-4|5|6|7|1O|8|@]|9|@]|A|$]]|$1|16|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|17|$]]

short recommendation: 
don't use isReachable(), call the system ping, as proposed in some of the answers above.

long explanation: 

<ul>
<li>ping uses the ICMP network protcol. To use ICMP, a 'raw socket' is needed</li>
<li>standard users are not allowed by the operating system to use raw sockets</li>
<li>the following applies to a fedora 30 linux, windows systems should be similar </li>
<li>if java runs as root, isReachable() actually sends ICMP ping requests</li>
<li>if java does not run as root, isReachable() tries to connect to TCP port 7, known as the echo port. This service is commonly not used any more, trying to use it might yield improper results</li>
<li>any kind of answer to the connection request, also a reject (TCP flag RST) yields a 'true' from isReachable()</li>
<li>some firewalls send RST for any port that is not explicitly open. If this happens, you will get isReachable() == true for a host that does not even exist</li>
<li>further tries to assign the necessary capabilities to a java process:</li>
<li>setcap cap_net_raw+eip java executable (assign the right to use raw sockets)</li>
<li>test: getcap java executable -> 'cap_net_raw+eip' (capability is assigned)</li>
<li>the running java still sends a TCP request to port 7</li>
<li>check of the running java process with getpcaps pid shows that the running java does not have the raw socket capablity. Obviously my setcap has been overridden by some security mechanism</li>
<li>as security requirements are increasing, this is likely to become even more restricted, unless s.b. implements an exception especially for ping (but nothing found on the net so far)</li>
</ul>

blocks|key|3084657|text|我更喜欢这样：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3084658|+++/**
+++++*
+++++*+@param+host
+++++*+@return+true+means+ping+success,false+means+ping+fail.
+++++*+@throws+IOException
+++++*+@throws+InterruptedException
+++++*/
++++private+static+boolean+ping(String+host)+throws+IOException,+InterruptedException+{
++++++++boolean+isWindows+=+System.getProperty("os.name").toLowerCase().contains("win");

++++++++ProcessBuilder+processBuilder+=+new+ProcessBuilder("ping",+isWindows?+"-n"+:+"-c",+"1",+host);
++++++++Process+proc+=+processBuilder.start();
++++++++return+proc.waitFor(200,+TimeUnit.MILLISECONDS);
++++}|code-block|syntax|javascript|3084659|这种方式可以将阻塞时间限制在特定的时间内，例如200ms。|3084660|它在MacOS、Android和Windows上运行良好，应该在jdk1.8中使用。|3084661|3084662|这个想法来自Mohammad+Banisaeid，但我无可奉告。(你必须有50个声誉才能评论)|blockquote|offset|length|3084663|3084664|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/users/671988/mohammad-banisaeid^0|0|0|0|0|0|6|I|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|11|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|13|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|14|8|@]|9|@$O|15|P|16|1|17]]|A|$]]|$1|Q|3|-4|5|6|7|18|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|S|$T|$5|U|V|W|A|$X|Y]]]]

I prefer to this way:
<pre class="lang-java prettyprint-override"><code> /**
 *
 * @param host
 * @return true means ping success,false means ping fail.
 * @throws IOException
 * @throws InterruptedException
 */
 private static boolean ping(String host) throws IOException, InterruptedException {
 boolean isWindows = System.getProperty(&quot;os.name&quot;).toLowerCase().contains(&quot;win&quot;);

 ProcessBuilder processBuilder = new ProcessBuilder(&quot;ping&quot;, isWindows? &quot;-n&quot; : &quot;-c&quot;, &quot;1&quot;, host);
 Process proc = processBuilder.start();
 return proc.waitFor(200, TimeUnit.MILLISECONDS);
 }
</code></pre>
This way can limit the blocking time to the specific time,such as 200 ms.
It works well in MacOS、Android and Windows, and should used in JDK 1.8.
<blockquote>
This idea comes from <a href="https://stackoverflow.com/users/671988/mohammad-banisaeid">Mohammad Banisaeid</a>,but I can't comment.
(You must have 50 reputation to comment)
</blockquote>

I am using this part of code to ping an ip address in java but only pinging localhost is successful and for the other hosts the program says the host is unreachable.
I disabled my firewall but still having this problem

<pre><code>public static void main(String[] args) throws UnknownHostException, IOException {
 String ipAddress = "127.0.0.1";
 InetAddress inet = InetAddress.getByName(ipAddress);

 System.out.println("Sending Ping Request to " + ipAddress);
 System.out.println(inet.isReachable(5000) ? "Host is reachable" : "Host is NOT reachable");

 ipAddress = "173.194.32.38";
 inet = InetAddress.getByName(ipAddress);

 System.out.println("Sending Ping Request to " + ipAddress);
 System.out.println(inet.isReachable(5000) ? "Host is reachable" : "Host is NOT reachable");
}
</code></pre>

The output is:

<blockquote>
 Sending Ping Request to 127.0.0.1 
 Host is reachable 
 Sending Ping Request to 173.194.32.38 
 Host is NOT reachable
</blockquote>

How to ping an IP address

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在使用这部分代码在java中ping一个ip地址，但只有ping本地主机成功，而对于其他主机，程序显示主机是无法访问的。我禁用了防火墙，但仍然有这个问题public static void main(String[] args) throws UnknownHostException, IOException { ...

问如何ping通IP地址
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