1.如果不想用花生殼這類的工具，可以利用阿里雲的動態域名解析api來動態解析域名。
2.原理就是定期檢查ip是否改變，如果改變就利用api重新解析域名

一、pom.xml

 <dependencies>
        <!--retrofit-->
        <dependency>
            <groupId>com.squareup.retrofit2</groupId>
            <artifactId>retrofit</artifactId>
            <version
 
>2.2.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.squareup.retrofit/converter-gson -->
        <dependency>
            <groupId>com.squareup.retrofit2</groupId>
            <artifactId>converter-gson</artifactId>
            <version
 
>2.2.0</version>
        </dependency>

        <!--ok-http-->
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>3.7.0</version>
        </dependency>

        <dependency
 
>
            <groupId>com.aliyun</groupId>
            <artifactId>aliyun-java-sdk-alidns</artifactId>
            <version>2.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.aliyun</groupId>
            <artifactId>aliyun-java-sdk-core</artifactId>
            <version>3.5.0</version>
        </dependency>
    </dependencies>

二、

import com.aliyuncs.DefaultAcsClient;
import com.aliyuncs.IAcsClient;
import com.aliyuncs.alidns.model.v20150109.DescribeDomainRecordsRequest;
import com.aliyuncs.alidns.model.v20150109.DescribeDomainRecordsResponse;
import com.aliyuncs.alidns.model.v20150109.UpdateDomainRecordRequest;
import com.aliyuncs.alidns.model.v20150109.UpdateDomainRecordResponse;
import com.aliyuncs.profile.DefaultProfile;
import com.aliyuncs.profile.IClientProfile;
import http.RetroFitHelper;

import java.util.List;

public class start {
    private static IAcsClient client = null;


    static {
        String regionId = "cn-hangzhou"; //必填固定值，必須為“cn-hanghou”
        String accessKeyId = ""; // your accessKey
        String accessKeySecret = "";// your accessSecret
        //或者設定為空，然後下邊有從阿里雲獲取的方法，只是不建議每次都去阿里雲獲取。

        IClientProfile profile = DefaultProfile.getProfile(regionId, accessKeyId, accessKeySecret);

        // 若報Can not find endpoint to access異常，請新增以下此行程式碼
        // DefaultProfile.addEndpoint("cn-hangzhou", "cn-hangzhou", "Alidns", "alidns.aliyuncs.com");
        client = new DefaultAcsClient(profile);
    }
    public static void main(String[] args) throws Exception {
        String domain = "xxx.com";  //頂級域名
        String rr = "yyy";//子域名
        DescribeDomainRecordsResponse.Record record = GetRecordId(domain, rr);
        String recordId = record.getRecordId();
        String ip = record.getValue();
        if (recordId==null|| recordId == "") return;
        if (ip==null|| ip == "") return;


        String curIp = RetroFitHelper.getCurIp();   //獲取對外ip地址
        if (!ip.equals(curIp)){
            UpdateDomainRecordRequest request = new UpdateDomainRecordRequest();
            request.setRecordId(recordId);
            request.setRR(record.getRR());
            request.setType(record.getType());
            request.setValue(curIp);
            request.setTTL(record.getTTL());
            request.setLine(record.getLine());
            request.setPriority(10l);

            UpdateDomainRecordResponse response = client.getAcsResponse(request);

            System.out.println(response.getRecordId());
        }
    }


    private static DescribeDomainRecordsResponse.Record GetRecordId(String domainString,String rr) {
        DescribeDomainRecordsRequest request = new DescribeDomainRecordsRequest();
        request.setDomainName(domainString);
        request.setRRKeyWord(rr);
        DescribeDomainRecordsResponse response;
        // describeRegionsRequest.setProtocol(ProtocolType.HTTPS); //指定訪問協議
        // describeRegionsRequest.setAcceptFormat(FormatType.JSON); //指定api返回格式
        // describeRegionsRequest.setMethod(MethodType.POST); //指定請求方法
        // describeRegionsRequest.setRegionId("cn-hangzhou");//指定要訪問的Region,僅對當前請求生效，不改變client的預設設定。
        try {
            response = client.getAcsResponse(request);
            List<DescribeDomainRecordsResponse.Record> list = response.getDomainRecords();
            for (DescribeDomainRecordsResponse.Record record : list) {
                if (domainString.equals(record.getDomainName()) && rr.equals(record.getRR())) {
                    return record;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

}