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;    //讀取偏好, 這里默認的是從主節點讀取.    private ReadPreference readPreference = ReadPreference.primary();    //使用服務器默認的寫關注?    private WriteConcern writeConcern = WriteConcern.ACKNOWLEDGED;    //使用服務的默認讀關注,默認是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;    //設置服務器選擇超時（以毫秒為單位），它定義驅動程序在拋出異常之前等待服務器選擇成功的時間    //值為0表示如果沒有可用的服務器，它將立即超時。 負值意味著無限期等待    private int serverSelectionTimeout = 1000 * 30;    //線程等待連接變為可用的最長時間    private int maxWaitTime = 1000 * 60 * 2;    // 線程池中連接的最大空閑時間    private int maxConnectionIdleTime;    private int maxConnectionLifeTime;    //連接超時時間,必須大于0    private int connectTimeout = 1000 * 10;    //socket超時時間    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;    //設置心跳頻率。 這是驅動程序將嘗試確定群集中每個服務器的當前狀態的頻率。 默認值為10,000毫秒    private int heartbeatFrequency = 10000;    //設置最小心跳頻率。 如果驅動程序必須經常重新檢查服務器的可用性，它將至少在上一次檢查后等待很長時間，以避免浪費精力。 默認值為500毫秒。    private int minHeartbeatFrequency = 500;    //設置用于集群心跳的連接的連接超時    private int heartbeatConnectTimeout = 20000;    //設置用于集群心跳的連接的套接字超時    private int heartbeatSocketTimeout = 20000;    //本地閾值    private int localThreshold = 15;    private String requiredReplicaSetName;    private DBDecoderFactory dbDecoderFactory = DefaultDBDecoder.FACTORY;    private DBEncoderFactory dbEncoderFactory = DefaultDBEncoder.FACTORY;    private SocketFactory socketFactory;    private boolean cursorFinalizerEnabled = true;...}

//讀取偏好, 首先從從節點讀取.private ReadPreference readPreference = ReadPreference.secondaryPreferred();//寫關注為1 ,寫入主節點即返回.private WriteConcern writeConcern = WriteConcern.W1;//使用服務的默認讀關注,默認是local(決定到某個讀取數據時，能讀到什么樣的數據)private ReadConcern readConcern = ReadConcern.LOCAL;

//線程池空閑時保持的最小連接數minConnectionsPerHost=20//線程池允許的最大連接數connectionsPerHost=100//connectionsPerHost* 5 =最大隊列數threadsAllowedToBlockForConnectionMultiplier=5//線程池中連接的最大空閑時間,5分鐘maxConnectionIdleTime = 5*60*1000 // 線程池中連接的最長生存時間,采用默認值maxConnectionLifeTime

//設置服務器選擇超時（以毫秒為單位），它定義驅動程序在拋出異常之前等待服務器選擇成功的時間//值為0表示如果沒有可用的服務器，它將立即超時。 負值意味著無限期等待private int serverSelectionTimeout = 1000 * 30;//連接超時時間,必須大于0private int connectTimeout = 1000 * 5;//線程等待連接變為可用的最長時間.maxWaitTime=6000