springboot内置了mongo驱动，默认配置localhost：27017，若本机没有配置mongoDB，则会连接失败。报错。
com.mongodb.MongoSocketOpenException: Exception opening socket
at com.mongodb.connection.SocketStream.open(SocketStream.java:63) ~[mongo-java-driver-3.2.2.jar!/:na]
at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:114) ~[mongo-java-driver-3.2.2.jar!/:na]
at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:128) ~[mongo-java-driver-3.2.2.jar!/:na]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_102]
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_102]
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_102]
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_102]
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_102]
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_102]
at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_102]
at com.mongodb.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:50) ~[mongo-java-driver-3.2.2.jar!/:na]
at com.mongodb.connection.SocketStream.open(SocketStream.java:58) ~[mongo-java-driver-3.2.2.jar!/:na]
... 3 common frames omitted
解决方法：
springbootapplication注解上面声明取消mongo自动配置
@SpringBootApplication(exclude = {MongoAutoConfiguration.class, MongoDataAutoConfiguration.class})
