How can I log actual queries to MongoDB with mongo java driver

If you're using Spring Boot 1.5.x (I'm on 1.5.19) you'll need to override the version of org.mongodb:mongodb-driver to at least version 3.7.0 to get the additional info in the logs.

See this ticket for more details: https://jira.mongodb.org/browse/JAVA-2698

You can set the logger level for org.mongodb to DEBUG and your Java driver will emit detailed logging like this:

2018-01-18 16:51:07|[main]|[NA]|INFO |org.mongodb.driver.connection|Opened connection [connectionId{localValue:2, serverValue:39}] to localhost:27017  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.insert|Inserting 1 documents into namespace stackoverflow.sample on connection [connectionId{localValue:2, serverValue:39}] to server localhost:27017  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.insert|Insert completed  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.command|Sending command {find : BsonString{value='sample'}} to database stackoverflow on connection [connectionId{localValue:2, serverValue:39}] to server localhost:27017  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.command|Command execution completed  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.command|Sending command {findandmodify : BsonString{value='sample'}} to database stackoverflow on connection [connectionId{localValue:2, serverValue:39}] to server localhost:27017  
2018-01-18 16:51:07|[main]|[NA]|DEBUG|org.mongodb.driver.protocol.command|Command execution completed  

In the above log output you can see the details of a query submitted by the client:

org.mongodb.driver.protocol.command|Sending command {find : BsonString{value='sample'}}

Alternatively, you can enable profiling on the server side ...

db.setProfilingLevel(2)

... causes the MongoDB profiler to collect data for all operations against that database.

The profiler output (which includes the query submitted by the client) is written to the system.profile collection in whichever database profiling has been enabled.

More details in the docs but the short summary is:

// turn up the logging
db.setProfilingLevel(2)

// ... run some commands

// find all profiler documents, most recent first
db.system.profile.find().sort( { ts : -1 } )

// turn down the logging
db.setProfilingLevel(0)