MongoDB Java access

MongoDB Java drivers have provided comprehensive operations, divided into three parts:

1. Common user operations

2. Administrator operations

3. oplog operations

You can add an eclipse testng plug-in and import the testng. jar package to the project.

This article describes the usage and precautions.

1. Connect a replica set (replica sets) into D:

The replica set is a mongo solution for stability and can implement read/write splitting. Here we introduce the java connection method of the replica set.

[Java]

1. StaticMongo m;
3. Static{
4. List <ServerAddress> addresslist =NewArrayList <ServerAddress> ();
5. Try{
6. Addresslist. add (NewServerAddress ("Fig: 10240"));
7. Addresslist. add (NewServerAddress ("Fig: 11240"));
8. Addresslist. add (NewServerAddress ("Fig: 12240"));
9. }Catch(UnknownHostException e ){
10. System. err. println ("Address check error .");
11. System. exit (-1);
12. }
14. Optional options =NewUsing options ();
15. Options. autoConnectRetry =True;
16. Options. connectionsPerHost =20;
17. Options. connectTimeout =6000;
18. Options. maxAutoConnectRetryTime =12000;
19. Options. maxWaitTime =12000;
20. Options. socketKeepAlive =True;
21. Options. socketTimeout =2000;
23. Try{
24. M =NewMongo (addresslist, options );
25. }Catch(Except exception e ){
26. System. err. println ("Mongo create error .");
27. System. exit (-1);
28. }
29. }

Note: The connection method used in the general example is to directly connect to a mongod service, but as a single production environment, the security is obviously insufficient. Therefore, the replica set method is used, and the connection is different from the general method.

[Java]

1. PublicMongo (List <ServerAddress> replicaSetSeeds, using options)ThrowsExcept exception

Method.

When options is set according to your needs, there are already many parameter descriptions.

Note that mongo instances use Singleton mode.

2. Obtain the database:

[Java]

1. DB db = m. getDB ("Test");

Note: Obtain the database named test for the operation. If the database does not exist, the Operation will create the corresponding database.

3. Get the set:

[Java]

1. DBCollection col = db. getCollection ("Offer");

Note: This is a set named offer. It is similar to a db table.

The above three operations are to establish a connection, followed by common operations in db.

4. Query:

[Java]

1. DBCursor cursor = col. find ();
2. While(Cursor. hasNext ()){
3. System. out. println (cursor. next ());
4. I ++;
5. }

Note: The full-set query outputs each record. Normally, similar operations are not performed. remember two things: find () and cursor.

[Java]

1. BasicDBObject query =NewBasicDBObject ();
2. Query =NewBasicDBObject ();
3. Query. put ("I",NewBasicDBObject ("$ Gt",20). Append ("$ Lte",30));// I. e. 20 <I <= 30
4. <Pre name ="Code" Class="Java"> DBCursor cur = coll. find (query );
5. While(Cur. hasNext ()){
6. System. out. println (cur. next ());
7. }

Note: query the offer information of a specified condition.

[Java]

1. DBObject tmpdoc = col. findOne (doc );

Note: query a single record. When it is clear that one record has only one record, findOne () is more convenient to avoid the trouble of moving the cursor.

5. Update:

[Java]

1. DBObject tmpdoc = col. findOne (doc );
2. Tmpdoc. put ("I", (Integer) tmpdoc. get ("I") +1);
3. System. out. println ("Update obj :"+ Col. findOne (tmpdoc ));

Note: to update a record, read the entire record and then update some information before writing it, Do not read some updates back.

6. insert:

[Java]

1. IntI =1000;
2. BasicDBObject doc =NewBasicDBObject ();
3. Doc. put ("I", I +1);
4. Col. insert (doc );
5. System. out. println ("Insert obj :"+ Col. findOne (doc ));

Note: Insert a record {I: 1001}, _ id is automatically generated.

7. Delete:

[Java]

1. BasicDBObject doc =NewBasicDBObject ();
2. Doc. put ("I", I +1);
4. Col. remove (doc );
5. System. out. println ("Insert obj :"+ Col. findOne (doc ));

Note: delete a record.