window上mongodb错误：No connection could be made

今天在慕课网（很不错的一个it技术免费网站）上学习nodejs开发电影网站，其中使用到了mongo数据库，但是在执行中遇到了如下错误！

failed to connect to 127.0.0.1:27017, reason: errno:10061 no connection could be made because the target machine actively refused it.

...

error: couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connection attempt failed at src/mongo/shell/mongo.js:146 exception: connect failed

在http://stackoverflow.com/questions/23726684/mongodb-on-a-windows-7-machine-no-connection-could-be-made中找到了解决办法，如下：

i got same error and fixed it by:

1) mkdir c:\data

2) cd data

3) mongod -dbpath .

4) now in another command window i was able to connect from my client using "mongo" command.

试了一下，使用两个命令行，一个用于接收连接，一个用于发送连接。问题是解决了，但是还是没发现问题的本质原因，如有知道了，请给我留言，谢谢各位。