mongodb连接失败

[Wendy晓晓晓]

Android studio开发，遇到问题：
Unable to start activity ComponentInfo{com.example.myapplication/com.example.myapplication.MainActivity}: com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: Connection refused}}]


我用的包是org.mongodb:mongodb-driver-sync:3.8.1
代码如下：