public class

Mongo

extends Object
java.lang.Object
   ↳ com.mongodb.Mongo

Class Overview

A database connection with internal pooling. For most application, you should have 1 Mongo instance for the entire JVM. The following are equivalent, and all connect to the local database running on the default port: 

 Mongo mongo1 = new Mongo( "127.0.0.1" );
 Mongo mongo2 = new Mongo( "127.0.0.1", 27017 );
 Mongo mongo3 = new Mongo( new DBAddress( "127.0.0.1", 27017, "test" ) );
 Mongo mongo4 = new Mongo( new ServerAddress( "127.0.0.1") );
Mongo instances have connection pooling built in - see the requestStart and requestDone methods for more information. http://www.mongodb.org/display/DOCS/Java+Driver+Concurrency

Connecting to a Replica Set

You can connect to a replica set using the Java driver by passing several a list if ServerAddress to the Mongo constructor. For example: 

 List addrs = new ArrayList();
 addrs.add( new ServerAddress( "127.0.0.1" , 27017 ) );
 addrs.add( new ServerAddress( "127.0.0.1" , 27018 ) );
 addrs.add( new ServerAddress( "127.0.0.1" , 27019 ) );

 Mongo mongo = new Mongo( addrs );

By default, all read and write operations will be made on the master. But it's possible to read from the slave(s) by using slaveOk: 

 mongo.slaveOk();

Summary

Nested Classes
class Mongo.Holder Mongo.Holder can be used as a static place to hold several instances of Mongo. 
Constants
int MAJOR_VERSION This constant is deprecated. Replaced by Mongo.getMajorVersion()
int MINOR_VERSION This constant is deprecated. Replaced by Mongo.getMinorVersion()
Public Constructors
Mongo()
Creates a Mongo instance based on a (single) mongodb node (localhost, default port)
Mongo(String host)
Creates a Mongo instance based on a (single) mongodb node (default port)
Mongo(String host, MongoOptions options)
Creates a Mongo instance based on a (single) mongodb node (default port)
Mongo(String host, int port)
Creates a Mongo instance based on a (single) mongodb node
Mongo(ServerAddress addr)
Creates a Mongo instance based on a (single) mongodb node
Mongo(ServerAddress addr, MongoOptions options)
Creates a Mongo instance based on a (single) mongo node using a given ServerAddress
Mongo(ServerAddress left, ServerAddress right)

Creates a Mongo in paired mode.

Mongo(ServerAddress left, ServerAddress right, MongoOptions options)

Creates a Mongo connection in paired mode.

Mongo(List<ServerAddress> replicaSetSeeds)

Creates a Mongo based on a replica set, or pair.

Mongo(List<ServerAddress> replicaSetSeeds, MongoOptions options)

Creates a Mongo based on a replica set, or pair.

Mongo(MongoURI uri)
Creates a Mongo described by a URI.
Public Methods
void addOption(int option)
adds a default query option
void close()
closes the underlying connector, which in turn closes all open connections.
static DB connect(DBAddress addr)
returns a database object
String debugString()
returns a string representing the hosts used in this Mongo instance
void dropDatabase(String dbName)
Drops the database if it exists.
CommandResult fsync(boolean async)
Forces the master server to fsync the RAM data to disk This is done automatically by the server at intervals, but can be forced for better reliability.
CommandResult fsyncAndLock()
Forces the master server to fsync the RAM data to disk, then lock all writes.
ServerAddress getAddress()
Gets the address of the current master
List<ServerAddress> getAllAddress()
Gets a list of all server addresses used when this Mongo was created
String getConnectPoint()
Gets the current master's hostname
DBTCPConnector getConnector()
Gets the underlying TCP connector
DB getDB(String dbname)
gets a database object
List<String> getDatabaseNames()
gets a list of all database names present on the server@return
static int getMajorVersion()
Gets the major version of this library
int getMaxBsonObjectSize()
Gets the maximum size for a BSON object supported by the current master server.
static int getMinorVersion()
Gets the minor version of this library
MongoOptions getMongoOptions()
Returns the mongo options.
int getOptions()
gets the default query options
ReadPreference getReadPreference()
Gets the default read preference
ReplicaSetStatus getReplicaSetStatus()
Gets the replica set status object
List<ServerAddress> getServerAddressList()
Gets the list of server addresses currently seen by the connector.
Collection<DB> getUsedDatabases()
gets a collection of DBs used by the driver since this Mongo instance was created.
String getVersion()
gets this driver version
WriteConcern getWriteConcern()
Gets the default write concern
boolean isLocked()
Returns true if the database is locked (read-only), false otherwise.
void resetOptions()
reset the default query options
void setOptions(int options)
sets the default query options
void setReadPreference(ReadPreference preference)
Sets the read preference for this database.
void setWriteConcern(WriteConcern concern)
Sets the write concern for this database.
void slaveOk()
This method is deprecated. Replaced with ReadPreference.SECONDARY
String toString()
DBObject unlock()
Unlocks the database, allowing the write operations to go through.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final int MAJOR_VERSION

This constant is deprecated.
Replaced by Mongo.getMajorVersion()

Constant Value: 2 (0x00000002)

public static final int MINOR_VERSION

This constant is deprecated.
Replaced by Mongo.getMinorVersion()

Constant Value: 8 (0x00000008)

Public Constructors

public Mongo ()

Creates a Mongo instance based on a (single) mongodb node (localhost, default port)

Throws
UnknownHostException
MongoException
UnknownHostException

public Mongo (String host)

Creates a Mongo instance based on a (single) mongodb node (default port)

Parameters
host server to connect to
Throws
UnknownHostException if the database host cannot be resolved
MongoException

public Mongo (String host, MongoOptions options)

Creates a Mongo instance based on a (single) mongodb node (default port)

Parameters
host server to connect to
options default query options
Throws
UnknownHostException if the database host cannot be resolved
MongoException

public Mongo (String host, int port)

Creates a Mongo instance based on a (single) mongodb node

Parameters
host the database's host address
port the port on which the database is running
Throws
UnknownHostException if the database host cannot be resolved
MongoException

public Mongo (ServerAddress addr)

Creates a Mongo instance based on a (single) mongodb node

Parameters
addr the database address
Throws
MongoException
See Also

public Mongo (ServerAddress addr, MongoOptions options)

Creates a Mongo instance based on a (single) mongo node using a given ServerAddress

Parameters
addr the database address
options default query options
Throws
MongoException
See Also

public Mongo (ServerAddress left, ServerAddress right)

Creates a Mongo in paired mode.
This will also work for a replica set and will find all members (the master will be used by default).

Parameters
left left side of the pair
right right side of the pair
Throws
MongoException
See Also

public Mongo (ServerAddress left, ServerAddress right, MongoOptions options)

Creates a Mongo connection in paired mode.
This will also work for a replica set and will find all members (the master will be used by default).

Parameters
left left side of the pair
right right side of the pair
Throws
MongoException
See Also

public Mongo (List<ServerAddress> replicaSetSeeds)

Creates a Mongo based on a replica set, or pair. It will find all members (the master will be used by default). If you pass in a single server in the list, the driver will still function as if it is a replica set. If you have a standalone server, use the Mongo(ServerAddress) constructor.

Parameters
replicaSetSeeds Put as many servers as you can in the list and the system will figure out the rest.
Throws
MongoException
See Also

public Mongo (List<ServerAddress> replicaSetSeeds, MongoOptions options)

Creates a Mongo based on a replica set, or pair. It will find all members (the master will be used by default).

Parameters
replicaSetSeeds put as many servers as you can in the list. the system will figure the rest out
options default query options
Throws
MongoException
See Also

public Mongo (MongoURI uri)

Creates a Mongo described by a URI. If only one address is used it will only connect to that node, otherwise it will discover all nodes.

Throws
MongoException
UnknownHostException
MongoException
UnknownHostException
See Also

Public Methods

public void addOption (int option)

adds a default query option

public void close ()

closes the underlying connector, which in turn closes all open connections. Once called, this Mongo instance can no longer be used.

public static DB connect (DBAddress addr)

returns a database object

Parameters
addr the database address

public String debugString ()

returns a string representing the hosts used in this Mongo instance

public void dropDatabase (String dbName)

Drops the database if it exists.

Parameters
dbName name of database to drop
Throws
MongoException

public CommandResult fsync (boolean async)

Forces the master server to fsync the RAM data to disk This is done automatically by the server at intervals, but can be forced for better reliability.

Parameters
async if true, the fsync will be done asynchronously on the server.

public CommandResult fsyncAndLock ()

Forces the master server to fsync the RAM data to disk, then lock all writes. The database will be read-only after this command returns.

public ServerAddress getAddress ()

Gets the address of the current master

Returns
  • the address

public List<ServerAddress> getAllAddress ()

Gets a list of all server addresses used when this Mongo was created

public String getConnectPoint ()

Gets the current master's hostname

public DBTCPConnector getConnector ()

Gets the underlying TCP connector

public DB getDB (String dbname)

gets a database object

Parameters
dbname the database name

public List<String> getDatabaseNames ()

gets a list of all database names present on the server@return

Throws
MongoException

public static int getMajorVersion ()

Gets the major version of this library

Returns
  • the major version, e.g. 2

public int getMaxBsonObjectSize ()

Gets the maximum size for a BSON object supported by the current master server. Note that this value may change over time depending on which server is master. If the size is not known yet, a request may be sent to the master server

Returns
  • the maximum size

public static int getMinorVersion ()

Gets the minor version of this library

Returns
  • the minor version, e.g. 8

public MongoOptions getMongoOptions ()

Returns the mongo options.

public int getOptions ()

gets the default query options

public ReadPreference getReadPreference ()

Gets the default read preference

public ReplicaSetStatus getReplicaSetStatus ()

Gets the replica set status object

public List<ServerAddress> getServerAddressList ()

Gets the list of server addresses currently seen by the connector. This includes addresses auto-discovered from a replica set.

public Collection<DB> getUsedDatabases ()

gets a collection of DBs used by the driver since this Mongo instance was created. This may include DBs that exist in the client but not yet on the server.

public String getVersion ()

gets this driver version

public WriteConcern getWriteConcern ()

Gets the default write concern

public boolean isLocked ()

Returns true if the database is locked (read-only), false otherwise.

public void resetOptions ()

reset the default query options

public void setOptions (int options)

sets the default query options

public void setReadPreference (ReadPreference preference)

Sets the read preference for this database. Will be used as default for reads from any collection in any database. See the documentation for ReadPreference for more information.

Parameters
preference Read Preference to use

public void setWriteConcern (WriteConcern concern)

Sets the write concern for this database. Will be used as default for writes to any collection in any database. See the documentation for WriteConcern for more information.

Parameters
concern write concern to use

public void slaveOk ()

This method is deprecated.
Replaced with ReadPreference.SECONDARY

makes it possible to run read queries on slave nodes

See Also
  • com.mongodb.ReadPreference.SECONDARY

public String toString ()

public DBObject unlock ()

Unlocks the database, allowing the write operations to go through. This command may be asynchronous on the server, which means there may be a small delay before the database becomes writable.