import com.sun.jmx.snmp.SnmpEngineId; //导入依赖的package包/类
/**
 * Constructor. A Local Configuration Datastore is passed to the engine. It will be used to store and retrieve data (engine Id, engine boots).
 * <P> WARNING : The SnmpEngineId is computed as follow:
 * <ul>
 * <li> If an lcd file is provided containing the property "localEngineID", this property value is used.</li>.
 * <li> If not, if the passed engineID is not null, this engine ID is used.</li>
 * <li> If not, a time based engineID is computed.</li>
 * </ul>
 * This constructor should be called by an <CODE>SnmpEngineFactory</CODE>. Don't call it directly.
 * @param fact The factory used to instantiate this engine.
 * @param lcd The local configuration datastore.
 * @param engineid The engine ID to use. If null is provided, an SnmpEngineId is computed using the current time.
 * @throws UnknownHostException Exception thrown, if the host name located in the property "localEngineID" is invalid.
 */
public SnmpEngineImpl(SnmpEngineFactory fact,
                      SnmpLcd lcd,
                      SnmpEngineId engineid) throws UnknownHostException {

    init(lcd, fact);
    initEngineID();
    if(this.engineid == null) {
        if(engineid != null)
            this.engineid = engineid;
        else
            this.engineid = SnmpEngineId.createEngineId();
    }
    lcd.storeEngineId(this.engineid);
    if (SNMP_LOGGER.isLoggable(Level.FINER)) {
        SNMP_LOGGER.logp(Level.FINER, SnmpEngineImpl.class.getName(),
                "SnmpEngineImpl(SnmpEngineFactory,SnmpLcd,SnmpEngineId)",
                "LOCAL ENGINE ID: " + this.engineid);
    }
}