Android 获取系统存储空间大小（不是内存）

    public String getDataTotalSize(Context context){  
        StatFs sf = new StatFs(context.getCacheDir().getAbsolutePath());  
        long blockSize = sf.getBlockSize();  
        long totalBlocks = sf.getBlockCount();  
        return Formatter.formatFileSize(context, blockSize*totalBlocks);  
    }