org.mongodb.driver.cluster : Exception in monitor thread while connecting to server localhost:27017

com.mongodb.MongoSocketOpenException: Exception opening socket
    at com.mongodb.connection.SocketStream.open(SocketStream.java:63) ~[mongodb-driver-core-3.0.4.jar:na]
    at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:114) ~[mongodb-driver-core-3.0.4.jar:na]
    at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:127) ~[mongodb-driver-core-3.0.4.jar:na]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_45]
Caused by: java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) ~[na:1.8.0_45]
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) ~[na:1.8.0_45]
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:345) ~[na:1.8.0_45]
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_45]
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_45]
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) ~[na:1.8.0_45]
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_45]
    at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_45]
    at com.mongodb.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:50) ~[mongodb-driver-core-3.0.4.jar:na]
    at com.mongodb.connection.SocketStream.open(SocketStream.java:58) ~[mongodb-driver-core-3.0.4.jar:na]
    ... 3 common frames omitted

解决方案:

Spring Boot has a feature called "auto configuration". In this case, as soon as the Mongo driver is detected on the classpath, the MongoAutoConfiguration is activated with default values, which point to localhost:27017. If you don't want that behaviour, you can now either configure the properties for MongoDB (see http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-mongodb for valid property keys) or disable the MongoAutoConfiguration:

@SpringBootApplication(exclude = {MongoAutoConfiguration.class, MongoDataAutoConfiguration.class})