背景
springboot项目启动时，报错
com.mongodb.MongoSocketOpenException: Exception opening socketat com.mongodb.internal.connection.SocketStream.open(SocketStream.java:70) ~[mongodb-driver-core-3.11.2.jar:na]at com.mongodb.internal.connection.InternalStreamConnection.open(InternalStreamConnection.java:128) ~[mongodb-driver-core-3.11.2.jar:na]at com.mongodb.internal.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:117) ~[mongodb-driver-core-3.11.2.jar:na]at java.lang.Thread.run(Thread.java:748) [na:1.8.0_181]
Caused by: java.net.ConnectException: Connection refused: connectat java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) ~[na:1.8.0_181]at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) ~[na:1.8.0_181]at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_181]at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_181]at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_181]at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) ~[na:1.8.0_181]at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_181]at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_181]at com.mongodb.internal.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:64) ~[mongodb-driver-core-3.11.2.jar:na]at com.mongodb.internal.connection.SocketStream.initializeSocket(SocketStream.java:79) ~[mongodb-driver-core-3.11.2.jar:na]at com.mongodb.internal.connection.SocketStream.open(SocketStream.java:65) ~[mongodb-driver-core-3.11.2.jar:na]... 3 common frames omitted
并且用工具能够连接mongodb，已经排除是mongodb不能连接的问题
原因
项目中配置了自定义的MongoClient：
@Beanpublic MongoDatabase mongoDatabase() {String host = mongodbProperties.getHost();Integer port = mongodbProperties.getPort();MongoClientOptions.Builder options = new MongoClientOptions.Builder();options.connectionsPerHost(mongodbProperties.getPoolSize());options.threadsAllowedToBlockForConnectionMultiplier(mongodbProperties.getBlockSize());options.build();MongoClient mongoClient = null;ServerAddress serverAddress = new ServerAddress(mongodbProperties.getHost(), mongodbProperties.getPort());List<ServerAddress> seeds = new ArrayList<>();seeds.add(serverAddress);String userName = mongodbProperties.getUserName();String password = mongodbProperties.getPassword();if (StringUtils.isNotBlank(userName) && StringUtils.isNotBlank(password)){MongoCredential credentials = MongoCredential.createCredential(userName, mongodbProperties.getDatabase(), password.toCharArray());List<MongoCredential> credentialsList = new ArrayList<>();credentialsList.add(credentials);mongoClient = new MongoClient(seeds, credentialsList);}else {mongoClient = new MongoClient(host, port);}return mongoClient.getDatabase(mongodbProperties.getDatabase());}
而springboot在启动时会自动实例化一个MongoClient：
源码如下：
/** Copyright 2012-2019 the original author or authors.** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at** https://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package org.springframework.boot.autoconfigure.mongo;import com.mongodb.MongoClientURI;import org.springframework.boot.context.properties.ConfigurationProperties;/*** Configuration properties for Mongo.** @author Dave Syer* @author Phillip Webb* @author Josh Long* @author Andy Wilkinson* @author Eddú Meléndez* @author Stephane Nicoll* @author Nasko Vasilev* @author Mark Paluch* @author Artsiom Yudovin* @since 1.0.0*/
@ConfigurationProperties(prefix = "spring.data.mongodb")
public class MongoProperties {/*** Default port used when the configured port is {@code null}.*/public static final int DEFAULT_PORT = 27017;/*** Default URI used when the configured URI is {@code null}.*/public static final String DEFAULT_URI = "mongodb://localhost/test";/*** Mongo server host. Cannot be set with URI.*/private String host;/*** Mongo server port. Cannot be set with URI.*/private Integer port = null;/*** Mongo database URI. Cannot be set with host, port and credentials.*/private String uri;/*** Database name.*/private String database;/*** Authentication database name.*/private String authenticationDatabase;/*** GridFS database name.*/private String gridFsDatabase;/*** Login user of the mongo server. Cannot be set with URI.*/private String username;/*** Login password of the mongo server. Cannot be set with URI.*/private char[] password;/*** Fully qualified name of the FieldNamingStrategy to use.*/private Class<?> fieldNamingStrategy;/*** Whether to enable auto-index creation.*/private Boolean autoIndexCreation;public String getHost() {return this.host;}public void setHost(String host) {this.host = host;}public String getDatabase() {return this.database;}public void setDatabase(String database) {this.database = database;}public String getAuthenticationDatabase() {return this.authenticationDatabase;}public void setAuthenticationDatabase(String authenticationDatabase) {this.authenticationDatabase = authenticationDatabase;}public String getUsername() {return this.username;}public void setUsername(String username) {this.username = username;}public char[] getPassword() {return this.password;}public void setPassword(char[] password) {this.password = password;}public Class<?> getFieldNamingStrategy() {return this.fieldNamingStrategy;}public void setFieldNamingStrategy(Class<?> fieldNamingStrategy) {this.fieldNamingStrategy = fieldNamingStrategy;}public String getUri() {return this.uri;}public String determineUri() {return (this.uri != null) ? this.uri : DEFAULT_URI;}public void setUri(String uri) {this.uri = uri;}public Integer getPort() {return this.port;}public void setPort(Integer port) {this.port = port;}public String getGridFsDatabase() {return this.gridFsDatabase;}public void setGridFsDatabase(String gridFsDatabase) {this.gridFsDatabase = gridFsDatabase;}public String getMongoClientDatabase() {if (this.database != null) {return this.database;}return new MongoClientURI(determineUri()).getDatabase();}public Boolean isAutoIndexCreation() {return this.autoIndexCreation;}public void setAutoIndexCreation(Boolean autoIndexCreation) {this.autoIndexCreation = autoIndexCreation;}}
解决方法
禁用SpringBoot对Mongo的自动配置，以免和自定义的配置冲突，在SpringBoot启动类上加上：
@SpringBootApplication(exclude = MongoAutoConfiguration.class)
由此可见，在任何springboot项目中，如果自定义了MongoClient且交与了springboot管理，都需要排除掉springboot对mongodb的自动配置