Android2.2中WifiManager.calculateSignalLevel函数的BUG

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android.net.wifi.WifiManager.calculateSignalLevel(int rssi, int numLevels) 当传递的numLevels的值大于等于46的时候，会出现除数为0的错误。

该函数在Android2.2 sdk中的实现如下

    public static int calculateSignalLevel(int rssi, int numLevels) {        if (rssi <= MIN_RSSI) {            return 0;        } else if (rssi >= MAX_RSSI) {            return numLevels - 1;        } else {            int partitionSize = (MAX_RSSI - MIN_RSSI) / (numLevels - 1);//当numLevels > 46时，partitionSize = (-55 - -100) / (46 - 1) = 0            return (rssi - MIN_RSSI) / partitionSize;//错误：除数为0        }    }

可以自己实现该函数从而避免这一BUG：

    public static int calculateSignalLevel(int rssi, int numLevels){    int MIN_RSSI        = -100;    int MAX_RSSI        = -55;      int levels          = 101;                if (rssi <= MIN_RSSI) {            return 0;        } else if (rssi >= MAX_RSSI) {            return levels - 1;        } else {            float inputRange = (MAX_RSSI - MIN_RSSI);            float outputRange = (levels - 1);            return (int)((float)(rssi - MIN_RSSI) * outputRange / inputRange);        }    }

参考：

http://code.google.com/p/android/issues/detail?id=2555

http://stackoverflow.com/questions/2873469/issue-with-wifimanager-calculatesignallevelrssi-5