DNSJAVA 库返回"no records found"

Question

我在我的安卓项目"android studio"中使用dnsjava，我已经导入了库。但是当我运行代码时，我得到"找不到记录"有人遇到这种情况吗？我在这里找到了一篇讨论类似问题的帖子，但解决方案不起作用。因为我将查询类型更改为 ANY 或 A 或 NS。它只是不起作用。有谁知道这是否是由于库代码故障造成的？欢迎任何建议。

package org.pctechtips.netdroid.async;
import android.os.AsyncTask;
import android.util.Log;
import org.pctechtips.netdroid.response.DnsAsyncResponse;
import org.xbill.DNS.Lookup;
import org.xbill.DNS.Record;
import org.xbill.DNS.TextParseException;
import org.xbill.DNS.Type;
import java.lang.ref.WeakReference;
public class DnsLookupAsyncTask extends AsyncTask<String, Void, String> {
    private final WeakReference<DnsAsyncResponse> delegate;
    /**
     * Constructor to set the delegate
     *
     * @param delegate Called when the DNS lookup finishes
     */
    public DnsLookupAsyncTask(DnsAsyncResponse delegate) {
        this.delegate = new WeakReference<>(delegate);
    }
    /**
     * Performs the appropriate lookup for specified record type
     *
     * @param params
     * @return DNS answer
     */
    @Override
    protected String doInBackground(String... params) {
        String domain = params[0];
        int recordType = Integer.parseInt(params[1]);
        Record[] records;
        try {
            records = new Lookup("google.com", Type.ANY).run();
            Log.d("DNS", records.toString());
            if (records == null) {
                return "No records found.";
            }
            StringBuilder answer = new StringBuilder();
            for (Record record : records) {
                String rClass = this.parseRecordClass(record.getDClass());
                answer.append(String.format("%stttt%stttt%stttt%s%n%n", record.getName(), record.getTTL(), rClass, record.rdataToString()));
            }
            return answer.toString();
        } catch (TextParseException e) {
            return "Error performing lookup!";
        }
    }
    /**
     * Determines the string representation of the DNS record class
     *
     * @param recordClass Numeric record class
     * @return Human readable record class
     */
    private String parseRecordClass(int recordClass) {
        switch (recordClass) {
            case 1:
                return "IN";
            case 2:
                return "CS";
            case 3:
                return "CH";
            case 4:
                return "HS";
            default:
                return "IN";
        }
    }
    /**
     * Calls the delegate when the DNS lookup has finished
     *
     * @param result DNS answer
     */
    @Override
    protected void onPostExecute(String result) {
        DnsAsyncResponse activity = delegate.get();
        if (activity != null) {
            activity.processFinish(result);
        }
    }
}

Answer 1

Android Oreo进行了阻止查找DNS服务器的更改。 https://developer.android.com/about/versions/oreo/android-8.0-changes.html#o-pri

有关更多详细信息和解决方法，请参阅：https://stackoverflow.com/a/48973823/5420880。

作为 dnsjava 的特定解决方法，您可以通过 dns.server 系统属性提供以逗号分隔的 DNS 服务器列表。