修改DEMO代码，增加一些场景（extra.xlsx）

[fhdone]

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[zhuangjiaju]

没看懂 新增个xlsx 文件干啥用。然后新增了啥。

[fhdone]

xlsx原来就有的，增加了几个合并单元格，主要用来看下读取效果。 因为读取合并单元格的时候只有第一个cell有值，其他的都是空。

[zhuangjiaju]

如果要修改 03版本一起要修改的 具体改了啥 还是不是特别明白 就感觉一堆格式化了代码