他的回答从来都不起作用。与Java7无关。这不会测试at端口是否可用。它测试它是否处于侦听状态,IP地址是否可访问,等等。此外,这个测试非常慢(每个端口将近一秒钟)。当捕获IOException时,它不应该返回false吗?@BaroudiSafwen它完
他的回答从来都不起作用。与Java7无关。这不会测试at端口是否可用。它测试它是否处于侦听状态,IP地址是否可访问,等等。此外,这个测试非常慢(每个端口将近一秒钟)。当捕获IOException时,它不应该返回false吗?@BaroudiSafwen它完,java,sockets,port,Java,Sockets,Port,他的回答从来都不起作用。与Java7无关。这不会测试at端口是否可用。它测试它是否处于侦听状态,IP地址是否可访问,等等。此外,这个测试非常慢(每个端口将近一秒钟)。当捕获IOException时,它不应该返回false吗?@BaroudiSafwen它完全取决于异常的实际情况。对于ConnectException:“连接被拒绝”,它应该返回false。对于超时,它可能返回的任何内容都无效,因为实际答案未知。这就是为什么这项技术在这方面是无用的。不是要求的。不是要求的。还有套接字泄漏。这适用于U
他的回答从来都不起作用。与Java7无关。这不会测试at端口是否可用。它测试它是否处于侦听状态,IP地址是否可访问,等等。此外,这个测试非常慢(每个端口将近一秒钟)。当捕获IOException时,它不应该返回false吗?@BaroudiSafwen它完全取决于异常的实际情况。对于
ConnectException:“连接被拒绝”
,它应该返回false。对于超时,它可能返回的任何内容都无效,因为实际答案未知。这就是为什么这项技术在这方面是无用的。不是要求的。不是要求的。还有套接字泄漏。这适用于UDP端口。问题似乎是关于TCP端口的。谢谢,在macOS 11(大苏尔)上为我工作过
public static boolean isAvailable(int portNr) {
boolean portFree;
try (var ignored = new ServerSocket(portNr)) {
portFree = true;
} catch (IOException e) {
portFree = false;
}
return portFree;
}
/**
* Checks to see if a specific port is available.
*
* @param port the port to check for availability
*/
public static boolean available(int port) {
if (port < MIN_PORT_NUMBER || port > MAX_PORT_NUMBER) {
throw new IllegalArgumentException("Invalid start port: " + port);
}
ServerSocket ss = null;
DatagramSocket ds = null;
try {
ss = new ServerSocket(port);
ss.setReuseAddress(true);
ds = new DatagramSocket(port);
ds.setReuseAddress(true);
return true;
} catch (IOException e) {
} finally {
if (ds != null) {
ds.close();
}
if (ss != null) {
try {
ss.close();
} catch (IOException e) {
/* should not be thrown */
}
}
}
return false;
}
try {
log.debug("{}: Checking if port open by trying to connect as a client", portNumber);
Socket sock = new Socket("localhost", portNumber);
sock.close();
log.debug("{}: Someone responding on port - seems not open", portNumber);
return false;
} catch (Exception e) {
if (e.getMessage().contains("refused")) {
return true;
}
log.error("Troubles checking if port is open", e);
throw new RuntimeException(e);
}
private static boolean available(int port) {
System.out.println("--------------Testing port " + port);
Socket s = null;
try {
s = new Socket("localhost", port);
// If the code makes it this far without an exception it means
// something is using the port and has responded.
System.out.println("--------------Port " + port + " is not available");
return false;
} catch (IOException e) {
System.out.println("--------------Port " + port + " is available");
return true;
} finally {
if( s != null){
try {
s.close();
} catch (IOException e) {
throw new RuntimeException("You should handle this error." , e);
}
}
}
}
private static boolean available(int port) {
try (Socket ignored = new Socket("localhost", port)) {
return false;
} catch (IOException ignored) {
return true;
}
}
Sigar sigar = new Sigar();
int flags = NetFlags.CONN_TCP | NetFlags.CONN_SERVER | NetFlags.CONN_CLIENT; NetConnection[] netConnectionList = sigar.getNetConnectionList(flags);
for (NetConnection netConnection : netConnectionList) {
if ( netConnection.getLocalPort() == port )
return false;
}
return true;
Socket Skt;
String host = "localhost";
int i = 8983; // port no.
try {
System.out.println("Looking for "+ i);
Skt = new Socket(host, i);
System.out.println("There is a Server on port "
+ i + " of " + host);
}
catch (UnknownHostException e) {
System.out.println("Exception occured"+ e);
}
catch (IOException e) {
System.out.println("port is not used");
}
boolean isPortOccupied(int port) {
DatagramSocket sock = null;
try {
sock = new DatagramSocket(port);
sock.close();
return false;
} catch (BindException ignored) {
return true;
} catch (SocketException ex) {
System.out.println(ex);
return true;
}
}
import java.net.DatagramSocket;
import java.net.BindException;
import java.net.SocketException;
public static boolean isTcpPortAvailable(int port) {
try (ServerSocket serverSocket = new ServerSocket()) {
// setReuseAddress(false) is required only on OSX,
// otherwise the code will not work correctly on that platform
serverSocket.setReuseAddress(false);
serverSocket.bind(new InetSocketAddress(InetAddress.getByName("localhost"), port), 1);
return true;
} catch (Exception ex) {
return false;
}
}
/**
* Check to see if a port is available.
*
* @param port
* the port to check for availability.
*/
public static boolean isPortAvailable(int port) {
try (var ss = new ServerSocket(port); var ds = new DatagramSocket(port)) {
return true;
} catch (IOException e) {
return false;
}
}