Android: 檢查SD卡可用容量MB

public boolean isAvaiableSpace(float sizeMB){
 if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
   String sdcard =Environment.getExternalStorageDirectory().getPath();
   StatFs statFs =new StatFs(sdcard);
   long blockSize=statFs.getBlockSize();
   long ablocks  =statFs.getAvailableBlocks();
   float available=(float)((ablocks*blockSize)/(1024*1024));
   if (sizeMB > available)
       return false;
   else
       return true;
 }
 return false;
}