Use MongoClient()
to make a connection to a running MongoDB instance.
The following examples are not meant to provide an exhaustive list of ways to instantiate MongoClient
. For a complete list of the MongoClient constructors, see MongoClient() API documentation
.
Running MongoDB deployments to which to connect. For example, to connect to a standalone, you must have a running standalone.
The MongoDB Driver. See Installation for instructions on how to install the MongoDB driver.
The following import statements:
import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.ServerAddress;
import com.mongodb.MongoCredential;
import com.mongodb.MongoClientOptions;
import java.util.Arrays;
MongoClient
The MongoClient()
instance represents a pool of connections to the database; you will only need one instance of class MongoClient
even with multiple threads.
Typically you only create one MongoClient
instance for a given MongoDB deployment (e.g. standalone, replica set, or a sharded cluster) and use it across your application. However, if you do create multiple instances:
All resource usage limits (e.g. max connections, etc.) apply per MongoClient
instance.
To dispose of an instance, call MongoClient.close()
to clean up resources.
To connect to a standalone MongoDB instance:
You can instantiate a MongoClient
object without any parameters to connect to a MongoDB instance running on localhost on port 27017
:
MongoClient mongoClient = new MongoClient();
You can explicitly specify the hostname to connect to a MongoDB instance running on the specified host on port 27017
:
MongoClient mongoClient = new MongoClient( "host1" );
You can explicitly specify the hostname and the port:
MongoClient mongoClient = new MongoClient( "host1" , 27017 );
You can specify the MongoClientURI
connection string.
MongoClient mongoClient = new MongoClient(new MongoClientURI("mongodb://host1:27017"));
To connect to a replica set, you must specify one or more members to the MongoClient
constructor.
MongoDB will auto-discover the primary and the secondaries.
You can specify the members using the MongoClientURI
connection string:
To specify at least two members of the replica set:
MongoClient mongoClient = new MongoClient(
new MongoClientURI("mongodb://host1:27017,host2:27017,host3:27017"));
With at least one member of the replica set and the replicaSet
option:
MongoClient mongoClient = new MongoClient(
new MongoClientURI(
"mongodb://host1:27017,host2:27017,host3:27017/?replicaSet=myReplicaSet"));
You can specify a list of the all the replica set members’ ServerAddress
:
MongoClient mongoClient = new MongoClient(
Arrays.asList(new ServerAddress("host1", 27017),
new ServerAddress("host2", 27017),
new ServerAddress("host3", 27017)));
To connect to a sharded cluster, specify the mongos
instance or instances to the MongoClient
constructor.
To connect to a single mongos
instance:
You can specify the hostname and the port (or you can omit the parameters if mongos
is running on localhost
and port 27017
)
MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
You can specify the MongoClientURI
connection string:
MongoClient mongoClient = new MongoClient(new MongoClientURI("mongodb://localhost:27017"));
To connect to multiple mongos
instances:
You can specify the MongoClientURI
connection string with their hostnames and ports:
MongoClient mongoClient = new MongoClient(
new MongoClientURI("mongodb://host1:27017,host2:27017"));
You can specify a list of the mongos
instances’ ServerAddress
:
MongoClient mongoClient = new MongoClient(
Arrays.asList(new ServerAddress("host1", 27017),
new ServerAddress("host2", 27017)));
You can specify the connection settings using either the MongoClientURI
or MongoClientOptions
or both.
For example, you can specify TLS/SSL and authentication setting in the MongoClientURI
connection string:
MongoClientURI uri = new MongoClientURI("mongodb://user1:pwd1@host1/?authSource=db1&ssl=true");
MongoClient mongoClient = new MongoClient(uri);
You can also use MongoClientOptions
to specify TLS/SSL and the MongoCredential
for the authentication information:
String user; // the user name
String database; // the name of the database in which the user is defined
char[] password; // the password as a character array
// ...
MongoCredential credential = MongoCredential.createCredential(user, database, password);
MongoClientOptions options = MongoClientOptions.builder().sslEnabled(true).build();
MongoClient mongoClient = new MongoClient(new ServerAddress("host1", 27017),
Arrays.asList(credential),
options);
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