Question

java判断输入的字符串是否一个域名。

源代码为：
package com.phy.tools;

import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
* PingDomain.java
*
* @author 判断输入的域名是否有效
*/
public class PingDomain {

public void isDomain(String addressArr) throws IOException {
boolean flag=false;
InetAddress address = InetAddress.getByName(addressArr);
if(address.isReachable(30)){
flag=true;
}
System.out.println("是一个域名吗?"+flag);
System.out.println("---------------------------------------");
}

public static void main(String[] args) throws Exception {
PingDomain pmd = new PingDomain();
pmd.isDomain("111.a.htm");
}
}

运行时抛出:Exception in thread "main" java.net.UnknownHostException: 111.a.htm
这样的错误。

求解。

Answer 1

address.isReachable(30),这个不好使，ping得通这个函数也可能返回false
根据你的目标平台，修改"bytes from"即可

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;

/**
* PingDomain.java
*
* @author 判断输入的域名是否有效
*/
public class PingDomain {

public void isDomain(String addressArr) throws IOException {
boolean flag=false;
InetAddress address = null;
try {
address = InetAddress.getByName(addressArr);
System.out.println("address = " + address);
} catch (UnknownHostException e) {
System.out.println("输入非法！");
return;
}

System.out.println("是一个域名吗?"+isReachable(address.getHostAddress()));
System.out.println("---------------------------------------");
}

private boolean isReachable(String ip) {
Runtime r = Runtime.getRuntime();
int timeout = 2;
String pingCommand = "ping " + ip + " -w " + timeout;
BufferedReader in = null;
try {
Process p = r.exec(pingCommand);
if (p == null) {
System.out.println("Failed.");
}
in = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line = null;
while ( (line = in.readLine()) != null) {
System.out.println(line);
if (line.contains("bytes from")) {
System.out.println("Conected.");
p.destroy();
return true;
}
}
} catch (Exception ex) {
System.out.println("Failed.");
} finally {
try {
in.close();
} catch (Exception ex) {
}
}
return false;
}

public static void main(String[] args) throws Exception {
PingDomain pmd = new PingDomain();
BufferedReader in=new BufferedReader(new InputStreamReader(System.in));
String inputline=in.readLine();
pmd.isDomain(inputline);
}
}

Answer 2

InetAddress.getByName()这个是通过计算机名字来得到的地址，根本不是你所要求的判断域名是否有效，最终只是判断计算机名是否存在，而且你设的时间是isReachable(30)中30太小了，设置大点

Answer 3

public void isDomain(String addressArr) throws IOException 把这句的IOException改成Exception就行了啊！ 因为InetAddress address = InetAddress.getByName(addressArr);貌似也要抛出异常并且不是IOException