Java 实例 - 查看端口是否已使用
以下实例演示了如何检测端口是否已经使用:
实例
importjava.net.*;
importjava.io.*;
publicclassMain{publicstaticvoidmain(String[]args){SocketSkt;
Stringhost = "localhost";
if(args.length > 0){host = args[0];
}for(inti = 0; i < 1024; i++){try{System.out.println("查看 "+ i);
Skt = newSocket(host, i);
System.out.println("端口 " + i + " 已被使用");
}catch(UnknownHostExceptione){System.out.println("Exception occured"+ e);
break;
}catch(IOExceptione){}}}}
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
importjava.io.IOException;
importjava.net.InetSocketAddress;
importjava.net.Socket;
importjava.net.SocketAddress;
importjava.net.SocketTimeoutException;
publicclassMain{publicstaticvoidmain(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
*/publicstaticbooleanisSocketAliveUitlitybyCrunchify(StringhostName, intport){booleanisAlive = false;
// 创建一个套接字SocketAddresssocketAddress = newInetSocketAddress(hostName, port);
Socketsocket = newSocket();
// 超时设置,单位毫秒inttimeout = 2000;
log("hostName: " + hostName + ", port: " + port);
try{socket.connect(socketAddress, timeout);
socket.close();
isAlive = true;
}catch(SocketTimeoutExceptionexception){System.out.println("SocketTimeoutException " + hostName + ":" + port + ". " + exception.getMessage());
}catch(IOExceptionexception){System.out.println("IOException - Unable to connect to " + hostName + ":" + port + ". " + exception.getMessage());
}returnisAlive;
}privatestaticvoidlog(Stringstring){System.out.println(string);
}privatestaticvoidlog(booleanisAlive){System.out.println("是否真正在使用: " + isAlive + "\n");
}}
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