java DNS域名解析

package com.example.demo.util;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import javax.naming.Context;
import javax.naming.NamingException;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

public class DnsUtils {

    public static void main(String[] args) {
        String[] dnsServers = {"172.18.61.253"};
        Set<String> set = getAllIP("www.baidu.com",dnsServers,30,2);
        Iterator<String> it = set.iterator();
        while(it.hasNext()) {
            System.out.println(it.next());
        }
    }

    /**
     * (推荐)
     * 获取域名所有IP 支持高频次调用
     * @param domain  域名
     * @param dnsServers    DNS服务器列表
     * @param timeout 请求超时
     * @param retryCount    重试次数
     * @return
     */
    public static Set<String> getAllIP(String domain, String[] dnsServers,
                                       int timeout, int retryCount) {
        Set<String> ips = new HashSet<String>();

        for(String dnsServer: dnsServers) {
            List<String> ipList;
            try {
                ipList = getDNSRecs(domain, dnsServer, new String[]{"A"},
                        timeout, retryCount);
            } catch (NamingException e) {
                continue;
            }
            ips.addAll(ipList);
        }

        return ips;
    }

    /**
     * （不推荐）
     * 获取DNS服务器信息，高频次调用可能返回为空结果
     * @param domain  要获取DNS信息的域名
     * @param provider      DNS服务器
     * @param types   信息类型 "A"(IP信息)，"MX"
     * @param timeout 请求超时
     * @param retryCount    重试次数
     *
     * @return 所有信息组成的数组
     *
     * @throws NamingException
     *
     */

    @SuppressWarnings("rawtypes" )
    public static ArrayList<String> getDNSRecs(String domain, String provider,
                                               String [] types, int timeout, int retryCount) throws NamingException {

        ArrayList<String> results = new ArrayList<String>(15);

        Hashtable<String, String> env = new Hashtable<String, String>();

        env.put( "java.naming.factory.initial" ,
                "com.sun.jndi.dns.DnsContextFactory" );

        //设置域名服务器
        env.put(Context. PROVIDER_URL, "dns://" + provider);

        // 连接时间
        env.put( "com.sun.jndi.dns.timeout.initial" , String.valueOf(timeout));

        // 连接次数
        env.put( "com.sun.jndi.dns.timeout.retries" , String.valueOf(retryCount));

        DirContext ictx = new InitialDirContext(env);
        Attributes attrs = ictx.getAttributes(domain, types);

        for (Enumeration e = attrs.getAll(); e.hasMoreElements();) {
            Attribute a = (Attribute) e.nextElement();
            int size = a.size();
            for (int i = 0; i < size; i++) {
                results.add((String) a.get(i));
            }
        }
        return results;
    }
}

 

来源：CSDN

作者：晨曦下的微笑

链接：https://blog.csdn.net/sinat_15946141/article/details/103919970