异常如下：
com.mongodb.MongoSocketOpenException: Exception opening socket
at com.mongodb.connection.SocketStream.open(SocketStream.java:62) ~[mongodb-driver-core-3.6.3.jar:na]
at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:126) ~[mongodb-driver-core-3.6.3.jar:na]
at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:114) ~[mongodb-driver-core-3.6.3.jar:na]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_152]
Caused by: java.net.SocketTimeoutException: connect timed out
at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) ~[na:1.8.0_152]
at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) ~[na:1.8.0_152]
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_152]
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_152]
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_152]
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) ~[na:1.8.0_152]
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_152]
at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_152]
at com.mongodb.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:59) ~[mongodb-driver-core-3.6.3.jar:na]
at com.mongodb.connection.SocketStream.open(SocketStream.java:57) ~[mongodb-driver-core-3.6.3.jar:na]
… 3 common frames omitted

这个时候我们就要检查我们的SpringBoot项目的配置文件的MongoDB的ip地址是否有错误，我们可以利用远程连接工具secureCRT，输入ip addr，查看ip地址，结果会发现配置文件的ip和远程ip不一致，我们只需要将其改正一下，SpringBoot就可以正常运行MongoDB了。