Android DNS 获取

得到Android 客户端的DNS信息

方法1，运行command得到DNS，（getprop net.dns1/getprop net.dns2）

 1     private String getLocalDNS(){
 2         Process cmdProcess = null;
 3         BufferedReader reader = null;
 4         String dnsIP = "";
 5         try {
 6             cmdProcess = Runtime.getRuntime().exec("getprop net.dns1");
 7             reader = new BufferedReader(new InputStreamReader(cmdProcess.getInputStream()));
 8             dnsIP = reader.readLine();
 9             return dnsIP;
10         } catch (IOException e) {
11             return null;
12         } finally{
13             try {
14                 reader.close();
15             } catch (IOException e) {
16             }
17             cmdProcess.destroy();
18         }
19     }

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方法2，得到WiFiManager，WiFiManager中可以得到wifi的dns，ip等一些网络信息。

 1     public static Map<String,String> getWifiNetInfo(Context context){
 2         Map<String,String> wifiInfo = new HashMap<>();
 3         WifiManager wifi = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
 4         if(wifi  != null){
 5             DhcpInfo info = wifi.getDhcpInfo();
 6             wifiInfo.put("wifi-dns", intToIp(info.dns1) + ";" + intToIp(info.dns2));
 7             wifiInfo.put("wifi-gateway", intToIp(info.gateway));
 8             wifiInfo.put("wifi-ip", intToIp(info.ipAddress));
 9             wifiInfo.put("wifi-netmask", intToIp(info.netmask));
10             wifiInfo.put("wifi-leaseTime", String.valueOf(info.leaseDuration));
11             wifiInfo.put("wifi-dhcpServer", intToIp(info.serverAddress));
12         }
13         return wifiInfo;
14     }
15 
16     public static String intToIp(int addr) {
17         return  ((addr & 0xFF) + "." +
18                 ((addr >>>= 8) & 0xFF) + "." +
19                 ((addr >>>= 8) & 0xFF) + "." +
20                 ((addr >>>= 8) & 0xFF));
21     }

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在Android5.1上实验了方法1和方法2，方法2在手机wifi关闭后，dns,gateway,ip,netmask,leaseTime都得不到了，神奇的是dhcpServer竟然有值，实在不解。

方法1在4G/wifi都关闭后，依然可以得到dns信息，表现比较靠谱，推荐使用。