阿里云HttpClient跨天之后解析不了域名

也许这是一个少见的情况，我使用HttpClient写了一个调用第三方服务的请求，在本机测试和腾讯云上测试都没有问题，但是放到阿里云之后，刚启动的时候是没有问题的，但是每次过零点之后，就会报异常：

java.net.UnknownHostException: www.xxxx.com: System error,异常栈如下：

java.net.UnknownHostException: wwww.xxx.com: System error
        at java.base/java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
        at java.base/java.net.InetAddress$PlatformNameService.lookupAllHostAddr(InetAddress.java:925)
        at java.base/java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1505)
        at java.base/java.net.InetAddress$NameServiceAddresses.get(InetAddress.java:844)
        at java.base/java.net.InetAddress.getAllByName0(InetAddress.java:1495)
        at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1354)
        at java.base/java.net.InetAddress.getAllByName(InetAddress.java:1288)
        at org.apache.http.impl.conn.SystemDefaultDnsResolver.resolve(SystemDefaultDnsResolver.java:45)
        at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:111)
        at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:353)
        at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:380)
        at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:236)
        at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184)
        at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88)
        at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
        at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:107)

只要重启一下java进程就好了。

在网上查找，说是jvm dns缓存导致的，在启动参数中添加下面两个参数:

设置解析成功的域名记录JVM中缓存的有效时间，这里修改为1秒钟有效，0表示禁止缓存，-1表示永远有效

-Dsun.net.inetaddr.ttl=1

设置解析失败的域名记录JVM中缓存的有效时间，这里修改为1秒钟有效，0表示禁止缓存，-1表示永远有效

-Dsun.net.inetaddr.negative.ttl=1

但是我设置了，貌似没有什么效果，有条件的同学可以试试。

最终没办法 ，使用Java jdk 自带的http服务重新写了一个请求，观察一段时间不再报那个异常，具体原因还是清楚，如果有知道的，谢谢告知。

package global.util;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;
import org.apache.http.Header;
import global.common.log.DKLog;

public class HttpUtil {
    //发送https post请求
    public static String sendHttpsPostRequest(String data, String requestUri, Header... headers) {
        DataOutputStream wr = null;
        BufferedReader in = null;
 　　　 HttpsUrlConnection con = null;
        try {
            URL obj = new URL(requestUri);
           //https请求
            con = (HttpsURLConnection) obj.openConnection();
            if(headers != null) {
                for(Header header : headers) {
                    con.setRequestProperty(header.getName(), header.getValue());
                }
            }
            con.setRequestProperty("Content-Type", " application/json");
            con.setConnectTimeout(15000);
            // 添加请求头
            con.setRequestMethod("POST");
            // 发送Post请求
            con.setDoOutput(true);
            wr = new DataOutputStream(con.getOutputStream());
            wr.writeBytes(data);
            wr.flush();
            int responseCode = con.getResponseCode();
            if (responseCode == 200) {
                in = new BufferedReader(new InputStreamReader(con.getInputStream()));
                String inputLine;
                StringBuffer response = new StringBuffer();
                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                return response.toString();
            } else {
                DKLog.system.error("请求服务器异常，返回异常码：{}", responseCode);
            }
        } catch (Exception e) {
            DKLog.system.error("Http请求失败,{},data:{}", requestUri, data, e);
        } finally {
            if (wr != null) {
                try {
                    wr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
            if(con != null){
　　　　　　　　　　con.disconnect();
             }
        }
        return null;
    }

}

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