说明：  VB.Net实现7Bit编码与解码,7Bit编码主要用于对单字节字符进行编码，因为单字节字符的ASCII码在00～7F之间，最高位始终为0实际有效的只有7个Bit，因此可以通过编码的方式将无效的最高位利用起来从而达到使用7个字节存储8个单字节字符的目的。
(VB.Net Realize 7bit encoding and decoding. 7bit encoding is mainly used to encode single byte characters. Because the ASCII code of single byte character is between 00 and 7F, and the highest bit is always 0, only 7 bits are actually valid. Therefore, the highest invalid bit can be used by encoding to achieve the purpose of using 7 bytes to store 8 single byte characters.)