Using client to operate MongoDB replica-Set

For the MongoDB Java driver, after 2.10.0, the document reminds that the Mongo class will be abolished and the mongoclient class is encouraged at the beginning.

The following shows how a Java program uses the latest mongoclient class to write data to MongoDB.

Assume that there is already a replica-Set cluster, namely, D1, D2, and D3 virtual machines.

Create a Java application built by Maven. Maven exec plugin is used to conveniently execute jar packages and customize parameters.

Let's take a look at pom. xml:

  <build>    <plugins>      <plugin><groupId>org.codehaus.mojo</groupId><artifactId>exec-maven-plugin</artifactId><version>1.2.1</version><executions>  <execution>    <goals>      <goal>java</goal>    </goals>  </execution></executions><configuration>  <mainClass>org.freebird.dbtool.App</mainClass>  <arguments>    <argument>d1,d2,d3</argument>  </arguments></configuration>      </plugin>    </plugins>  </build>

Three parameters are passed. They are separated by commas (,). They are different host names: D1, D2, and D3.

Check out the code initialization section:

    public static void main(String[] args) throws UnknownHostException {System.out.println(args[0]);        String[] hosts = args[0].split(",");        int portNumber = 27017;        System.out.println(hosts[0]);        System.out.println(hosts[1]);        System.out.println(hosts[2]);                MongoClient client = new MongoClient(Arrays.asList(new ServerAddress(hosts[0], portNumber),                                      new ServerAddress(hosts[1], portNumber),                                      new ServerAddress(hosts[2], portNumber)));        MyApp.getInstance().setDbName("kaimei");        MyApp.getInstance().setClient(client);

The three hosts are separated, and three serveraddress objects are created, and then the Consumer Client object is constructed.

At the same time, a singleton object of MyApp is created to store this Consumer Client object, and getdb () is provided to facilitate database connection obtaining in the future.

public class MyApp {        private MyApp() {    }        public static MyApp getInstance() {        return MyAppHolder.INSTANCE;    }        private static class MyAppHolder {        private static final MyApp INSTANCE = new MyApp();    }        @Getter @Setter    String dbName;        @Setter    MongoClient client;        public DB getDB() {        return client.getDB(dbName);    }}

When you need to use a connection anywhere in the future:

    public static void bind(final String address, final String userId) {DB db = MyApp.getInstance().getDB();DBCollection collection = db.getCollection(DISPLAY_COLLECTION);DBObject condition = new BasicDBObject();condition.put("address", address);DBObject field = new BasicDBObject();field.put("user_id", new ObjectId(userId));DBObject set = new BasicDBObject();set.put("$set", field);collection.update(condition, set, false, false);    }

It's easy.