最近一個關於流量的專案在Android7.0系統的手機上執行，一直獲取不到流量的使用資料，檢視原始碼然後發現TrafficStats.getUidRxBytes(uid)和TrafficStats.getUidTxBytes(uid)一直都是返回的-1，

// 獲取某個網路UID接收和傳送位元組的總和
long total = TrafficStats.getUidRxBytes(uid)
        + TrafficStats.getUidTxBytes(uid);

這就納悶了！！！然後多方查詢資料，問了公司的大神，給我說可以在“/proc/uid_stat/"資料夾中讀取資料。後來總算是出來了。。。 不說了 貼程式碼

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

/**
     * 通過uid查詢資料夾中的資料
     * @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();
}