以下实例演示了如何检测端口是否已经使用： 实例 import java . net .*;
import java . io .*;
public class Main {
public static void main ( String [ ] args ) {
Socket Skt ;
String host = " localhost " ;
if ( args . length > 0 ) {
host = args [ 0 ] ;
}
for ( int i = 0 ; i < 1024 ; i ++ ) {
try {
System . out . println ( " 查看 " + i ) ;
Skt = new Socket ( host , i ) ;
System . out . println ( " 端口 " + i + " 已被使用 " ) ;
}
catch ( UnknownHostException e ) {
System . out . println ( " Exception occured " + e ) ;
break ;
}
catch ( IOException e ) {
}
}
}}
以上代码运行输出结果为：
……
查看 17
查看 18
查看 19
查看 20
查看 21
端口 21 已被使用
查看 22
查看 23
查看 24
……
也可以指定主机的端口： Main.java 文件 import java . io . IOException ;
import java . net . InetSocketAddress ;
import java . net . Socket ;
import java . net . SocketAddress ;
import java . net . SocketTimeoutException ;
public class Main {
public static void main ( String [ ] args ) {
// 检测本地 80 端口
log ( isSocketAliveUitlitybyCrunchify ( " localhost " , 80 ) ) ;
// 检测本地 8080 端口
log ( isSocketAliveUitlitybyCrunchify ( " localhost " , 8080 ) ) ;
// 检测本地 8081 端口
log ( isSocketAliveUitlitybyCrunchify ( " localhost " , 8081 ) ) ;
// 检测 runoob.com 的 80 端口
log ( isSocketAliveUitlitybyCrunchify ( " runoob.com " , 80 ) ) ;
// 检测 runoob.com 的 443 端口
log ( isSocketAliveUitlitybyCrunchify ( " runoob.com " , 443 ) ) ;
// 检测 runoob.com 的 81 端口
log ( isSocketAliveUitlitybyCrunchify ( " runoob.com " , 81 ) ) ;
}
/* *
* 判断主机端口
*
* @param hostName
* @param port
* @return boolean - true/false
*/
public static boolean isSocketAliveUitlitybyCrunchify ( String hostName , int port ) {
boolean isAlive = false ;
// 创建一个套接字
SocketAddress socketAddress = new InetSocketAddress ( hostName , port ) ;
Socket socket = new Socket ( ) ;
// 超时设置，单位毫秒
int timeout = 2000 ;
log ( " hostName: " + hostName + " , port: " + port ) ;
try {
socket . connect ( socketAddress , timeout ) ;
socket . close ( ) ;
isAlive = true ;
} catch ( SocketTimeoutException exception ) {
System . out . println ( " SocketTimeoutException " + hostName + " : " + port + " . " + exception . getMessage ( ) ) ;
} catch ( IOException exception ) {
System . out . println (
" IOException - Unable to connect to " + hostName + " : " + port + " . " + exception . getMessage ( ) ) ;
}
return isAlive ;
}
private static void log ( String string ) {
System . out . println ( string ) ;
}
private static void log ( boolean isAlive ) {
System . out . println ( " 是否真正在使用: " + isAlive + "" ) ;
}
}
以上代码运行输出结果为：
hostName: localhost, port: 80
IOException - Unable to connect to localhost:80. Connection refused
是否真正在使用: true
hostName: localhost, port: 8080
IOException - Unable to connect to localhost:8080. Connection refused
是否真正在使用: false
hostName: localhost, port: 8081
IOException - Unable to connect to localhost:8081. Connection refused
是否真正在使用: false
hostName: runoob.com, port: 80
是否真正在使用: true
hostName: runoob.com, port: 443
是否真正在使用: true
hostName: runoob.com, port: 81
SocketTimeoutException runoob.com:81. connect timed out
是否真正在使用: false
