格式和hiredis基本兼容:即%b对应二进制数据(指针+length),其他和printf的参数类似。对一些细节做了改进:当某个字段包含空格时,使用单引号或双引号包围起来会被视作一个字段。比如AddCommand("Set 'a key with space' 'a value with space as well'")中的key是a key with space,value是a value with space as well。在hiredis中必须写成redisvCommand(..., "SET %s %s", "a key with space", "a value with space as well");