connectionPoolSettings = ConnectionPoolSettings.builder()

                                                       .minSize(getMinConnectionsPerHost())

                                                       .maxSize(getConnectionsPerHost())

                                                       .maxWaitQueueSize(getThreadsAllowedToBlockForConnectionMultiplier()

                                                                         * getConnectionsPerHost())

                                                       .maxWaitTime(getMaxWaitTime(), MILLISECONDS)

                                                       .maxConnectionIdleTime(getMaxConnectionIdleTime(), MILLISECONDS)

                                                       .maxConnectionLifeTime(getMaxConnectionLifeTime(), MILLISECONDS)

                                                       .build();

public static class Builder {

        private String description;

        private String applicationName;

        //读取偏好, 这里默认的是从主节点读取.

        private ReadPreference readPreference = ReadPreference.primary();

        //使用服务器默认的写关注?

        private WriteConcern writeConcern = WriteConcern.ACKNOWLEDGED;

        //使用服务的默认读关注,默认是local

        private ReadConcern readConcern = ReadConcern.DEFAULT;

        private CodecRegistry codecRegistry = MongoClient.getDefaultCodecRegistry();

        private final List<CommandListener> commandListeners = new ArrayList<CommandListener>();

        private final List<ClusterListener> clusterListeners = new ArrayList<ClusterListener>();

        private final List<ServerListener> serverListeners = new ArrayList<ServerListener>();

        private final List<ServerMonitorListener> serverMonitorListeners = new ArrayList<ServerMonitorListener>();

        private int minConnectionsPerHost;

        private int maxConnectionsPerHost = 100;

        private int threadsAllowedToBlockForConnectionMultiplier = 5;

        //设置服务器选择超时（以毫秒为单位），它定义驱动程序在抛出异常之前等待服务器选择成功的时间

        //值为0表示如果没有可用的服务器，它将立即超时。 负值意味着无限期等待

        private int serverSelectionTimeout = 1000 * 30;

        //线程等待连接变为可用的最长时间

        private int maxWaitTime = 1000 * 60 * 2;

        // 线程池中连接的最大空闲时间

        private int maxConnectionIdleTime;

        private int maxConnectionLifeTime;

        //连接超时时间,必须大于0

        private int connectTimeout = 1000 * 10;

        //socket超时时间

        private int socketTimeout = 0;

        //socket是否保活

        private boolean socketKeepAlive = false;

        private boolean sslEnabled = false;

        private boolean sslInvalidHostNameAllowed = false;

        private boolean alwaysUseMBeans = false;

        //设置心跳频率。 这是驱动程序将尝试确定群集中每个服务器的当前状态的频率。 默认值为10,000毫秒

        private int heartbeatFrequency = 10000;

        //设置最小心跳频率。 如果驱动程序必须经常重新检查服务器的可用性，它将至少在上一次检查后等待很长时间，以避免浪费精力。 默认值为500毫秒。

        private int minHeartbeatFrequency = 500;

        //设置用于集群心跳的连接的连接超时

        private int heartbeatConnectTimeout = 20000;

        //设置用于集群心跳的连接的套接字超时

        private int heartbeatSocketTimeout = 20000;

        //本地阈值

        private int localThreshold = 15;

        private String requiredReplicaSetName;

        private DBDecoderFactory dbDecoderFactory = DefaultDBDecoder.FACTORY;

        private DBEncoderFactory dbEncoderFactory = DefaultDBEncoder.FACTORY;

        private SocketFactory socketFactory;

        private boolean cursorFinalizerEnabled = true;

...}