public static boolean sdCardIsAvailable() { 
  String status = Environment.getExternalStorageState(); 
  if (!status.equals(Environment.MEDIA_MOUNTED)) { 
   return false; 
  } 
  return true; 
} 

private static boolean hasExternalCacheDir() { 
  return Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO; 
} 
/** 
* @param context 上下文 
* @return The external cache dir SD卡路径 
*/ 
private static String getExternalCacheDir(Context context) { 
  // android 2.2 以后才支持的特性 
  if (hasExternalCacheDir()) { 
   return context.getExternalCacheDir().getPath() + File.separator + "gesture"; 
  } 
  // Before Froyo we need to construct the external cache dir ourselves 
  // 2.2以前我们需要自己构造 
  final String cacheDir = "/Android/data/" + context.getPackageName() + "/cache/gesture/"; 
  return Environment.getExternalStorageDirectory().getPath() + cacheDir; 
} 

public static long getRealSizeOnSdcard() { 
  File path = new File(Environment.getExternalStorageDirectory().getAbsolutePath()); 
  StatFs stat = new StatFs(path.getPath()); 
  long blockSize = stat.getBlockSize(); 
  long availableBlocks = stat.getAvailableBlocks(); 
  return availableBlocks * blockSize; 
} 

/** 
* @param updateSize 指定的检测空间大小 
* @return True 空间足够返回true,不足返回false 
*/ 
public static boolean enoughSpaceOnSdCard(long updateSize) { 
  String status = Environment.getExternalStorageState(); 
  if (!status.equals(Environment.MEDIA_MOUNTED)) 
   return false; 
  return (updateSize < getRealSizeOnSdcard()); 
} 

public static long getRealSizeOnPhone() { 
  File path = Environment.getDataDirectory(); 
  StatFs stat = new StatFs(path.getPath()); 
  long blockSize = stat.getBlockSize(); 
  long availableBlocks = stat.getAvailableBlocks(); 
  long realSize = blockSize * availableBlocks; 
  return realSize; 
} 

/** 
* @param updateSize 指定的检测空间大小 
* @return 空间足够返回true,不足返回false 
*/ 
public static boolean enoughSpaceOnPhone(long updateSize) { 
  return getRealSizeOnPhone() > updateSize; 
} 

/** 
* 获取底部虚拟按键高度(针对没有物理按键的手机) 
* @return 
*/ 
private int getNavigationBarHeight() { 
  int resourceId = getResources().getIdentifier("navigation_bar_height", "dimen", "android"); 
  if (resourceId > 0) { 
   return getResources().getDimensionPixelSize(resourceId); 
  } 
  return 0; 
}