关于Android获取流量计数TrafficStats.getUidRxBytes(uid)和TrafficStats.getUidTxBytes(uid)返回-1解决方案

最近一个关于流量的项目在Android7.0系统的手机上运行，一直获取不到流量的使用数据，查看源码然后发现TrafficStats.getUidRxBytes(uid)和TrafficStats.getUidTxBytes(uid)一直都是返回的-1，

// 获取某个网络UID接收和发送字节的总和
long total = TrafficStats.getUidRxBytes(uid)
+ TrafficStats.getUidTxBytes(uid);

这就纳闷了！！！然后多方查找资料，问了公司的大神，给我说可以在“/proc/uid_stat/"文件夹中读取数据。后来总算是出来了。。。 不说了 贴代码

if (total == 0 || (TrafficStats.getUidRxBytes(uid) == -1) && (TrafficStats.getUidTxBytes(uid) == -1)) {
total = getTotalBytesManual(uid);
}

/**
* 通过uid查询文件夹中的数据
* @param localUid
* @return
*/
private Long getTotalBytesManual(int localUid) {
//        Log.e("BytesManual*****", "localUid:" + localUid);
File dir = new File("/proc/uid_stat/");
String[] children = dir.list();
StringBuffer stringBuffer = new StringBuffer();
for (int i = 0; i < children.length; i++) {
stringBuffer.append(children[i]);
stringBuffer.append("   ");
}
//        Log.e("children*****", children.length + "");
//        Log.e("children22*****", stringBuffer.toString());
if (!Arrays.asList(children).contains(String.valueOf(localUid))) {
return 0L;
}
File uidFileDir = new File("/proc/uid_stat/" + String.valueOf(localUid));
File uidActualFileReceived = new File(uidFileDir, "tcp_rcv");
File uidActualFileSent = new File(uidFileDir, "tcp_snd");
String textReceived = "0";
String textSent = "0";
try {
BufferedReader brReceived = new BufferedReader(new FileReader(uidActualFileReceived));
BufferedReader brSent = new BufferedReader(new FileReader(uidActualFileSent));
String receivedLine;
String sentLine;

if ((receivedLine = brReceived.readLine()) != null) {
textReceived = receivedLine;
//                Log.e("receivedLine*****", "receivedLine:" + receivedLine);
}
if ((sentLine = brSent.readLine()) != null) {
textSent = sentLine;
//                Log.e("sentLine*****", "sentLine:" + sentLine);
}
} catch (IOException e) {
e.printStackTrace();
//            Log.e("IOException*****", e.toString());
}
//        Log.e("BytesManualEnd*****", "localUid:" + localUid);
return Long.valueOf(textReceived).longValue() + Long.valueOf(textSent).longValue();
}