MongoClient se connecte à la base de données

public class DbManager {
    
    
    private static volatile DbManager instance;

    private static final Logger logger = LoggerFactory.getLogger(DbManager.class);

    private MongoClient mongoClient;

    private DbManager() {
    
    

    }

    public static DbManager getInstance() {
    
    

        if (null == instance) {
    
    
            synchronized (DbManager.class) {
    
    
                if (null == instance) {
    
    
                    instance = new DbManager();
                    instance.init();
                }

            }
        }

        return instance;
    }

    private void init() {
    
    

        // 连接池选项
     
        // 选项构建者
        com.mongodb.MongoClientOptions.Builder builder = new MongoClientOptions.Builder();
        
        // 每个地址最大请求数
        builder.connectionsPerHost(8);
        builder.threadsAllowedToBlockForConnectionMultiplier(4);
        
        // 设置连接超时时间
        builder.connectTimeout(10000);
        
        // 设置最大等待时间
        builder.maxWaitTime(120000);
        
        // 读取数据的超时时间
        builder.socketTimeout(1500);

        MongoClientOptions options = builder.build();

        List<ServerAddress> hosts = new ArrayList<ServerAddress>();

        String host = "127.0.0.1";
        logger.info("dbhost:"+host);
        int port = 27017;
        ServerAddress serverAddress = new ServerAddress(host, port);
        hosts.add(serverAddress);

        List<MongoCredential> credentials = new ArrayList<MongoCredential>();

        MongoCredential credential = MongoCredential.createCredential("admin","admin","123456".toCharArray());  // 需要验证
        credentials.add(credential);
　　　　　//不使用用户名密码
       // mongoClient = new MongoClient(hosts);　　　　　　　　　//使用用户名密码
         mongoClient=new MongoClient(serverAddress, Arrays.asList(credential));

    }

    public MongoClient getMongoClient() {
    
    
        return mongoClient;
    }
    
    public DB getDataDb() {
    
    
        DB db = mongoClient.getDB("data");

        return db;
    }
}