Spring Boot data-mongodb连接MongoDB数据库失败

用了spring-boot-starter-data-mongodb模块后，连接本机的Mongodb一直失败，用户也创建了，密码也设了，就是连不上啊。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

总是报错：

com.mongodb.MongoSecurityException: Exception authenticating MongoCredential{mechanism=null, userName='test', source='test', password=<hidden>, mechanismProperties={}}
    at com.mongodb.connection.SaslAuthenticator.wrapException(SaslAuthenticator.java:162)
    at com.mongodb.connection.SaslAuthenticator.access$200(SaslAuthenticator.java:39)
    at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:68)
    at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:46)
    at com.mongodb.connection.SaslAuthenticator.doAsSubject(SaslAuthenticator.java:168)
    at com.mongodb.connection.SaslAuthenticator.authenticate(SaslAuthenticator.java:46)
    at com.mongodb.connection.DefaultAuthenticator.authenticate(DefaultAuthenticator.java:32)
    at com.mongodb.connection.InternalStreamConnectionInitializer.authenticateAll(InternalStreamConnectionInitializer.java:122)
    at com.mongodb.connection.InternalStreamConnectionInitializer.initialize(InternalStreamConnectionInitializer.java:52)
    at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:127)
    at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:114)
    at java.lang.Thread.run(Thread.java:748)
Caused by: com.mongodb.MongoCommandException: Command failed with error 18: 'Authentication failed.' on server localhost:27017. The full response is { "ok" : 0.0, "errmsg" : "Authentication failed.", "code" : 18, "codeName" : "AuthenticationFailed" }
    at com.mongodb.connection.ProtocolHelper.getCommandFailureException(ProtocolHelper.java:164)
    at com.mongodb.connection.InternalStreamConnection.receiveCommandMessageResponse(InternalStreamConnection.java:295)
    at com.mongodb.connection.InternalStreamConnection.sendAndReceive(InternalStreamConnection.java:255)
    at com.mongodb.connection.CommandHelper.sendAndReceive(CommandHelper.java:84)
    at com.mongodb.connection.CommandHelper.executeCommand(CommandHelper.java:34)
    at com.mongodb.connection.SaslAuthenticator.sendSaslContinue(SaslAuthenticator.java:123)
    at com.mongodb.connection.SaslAuthenticator.access$100(SaslAuthenticator.java:39)
    at com.mongodb.connection.SaslAuthenticator$1.run(SaslAuthenticator.java:65)
    ... 9 common frames omitted

References:

• https://segmentfault.com/q/1010000012110119
• https://www.jianshu.com/p/237a0c5ad9fa

由于mongodb在本机登录是不需要验证的，所以起初我认为是没有用户导致的，就去创建了用户。
用以下语句创建root用户，用户名和密码为root/123456。按需修改。

use admin  
db.createUser({
  user: 'root',  // 用户名
  pwd: '123456',  // 密码
  roles:[{
    role: 'root',  // 角色
    db: 'admin'  // 数据库
  }]
})

然后操作了下，发现还是报错，就创建了针对单数据库的普通用户。

use test // 跳转到需要添加用户的数据库
db.createUser({
    user: 'test', // 用户名
    pwd: '123456', // 密码
    roles: [{
        role: 'readWrite', // 角色拥有读写权限
        db: 'test' // 数据库
    }]
})

发现还是不行……
然后查了文章，发现不知道为什么配置文件的配置方式改下就行了，辣鸡mongo
连接失败的配置：

spring:
  data:
    mongodb:
      host: localhost
      port: 27017
      database: test
      username: test
      password: 123456

连接成功的配置：

spring:
  application:
    name: xc-service-manage-cms
  data:
    mongodb:
#      uri: mongodb://用户名:密码@IP:端口/数据库名
      uri: mongodb://test:123456@localhost:27017/test