有一个这样的场景，2台mysql数据库同步，正常的情况下一般只会连接其中的一台，如果其中一台down掉以后，应用程序能自动连接到另外一台，这样的场景和我上一篇文章描述的有所不同，详见: 《MySQL JDBC 集群》 一文，前面提到的是轮询访问，现在是一直访问一
有一个这样的场景，2台mysql数据库同步，正常的情况下一般只会连接其中的一台，如果其中一台down掉以后，应用程序能自动连接到另外一台，这样的场景和我上一篇文章描述的有所不同，详见:《MySQL JDBC 集群》一文，前面提到的是轮询访问，现在是一直访问一台，直到另外一台down机以后将会自动切换到另外一台上去，当然实现这样的场景你的应用程序必须使用JDBC的数据库连接池才会有效。
其实MySQL关于集群 的 JDBC参数还有很多，下面这些参数是我从MySQL官方网站上杂录的一部分，提供大家参考，
High Availability and Clustering.
| Property Name | Definition | Default Value | Since Version |
| autoReconnect | Should the driver try to re-establish stale and/or dead connections? If enabled the driver will throw an exception for a queries issued on a stale or dead connection, which belong to the current transaction, but will attempt reconnect before the next query issued on the connection in a new transaction. The use of this feature is not recommended, because it has side effects related to session state and data consistency when applications don't handle SQLExceptions properly, and is only designed to be used when you are unable to configure your application to handle SQLExceptions resulting from dead and stale connections properly. Alternatively, investigate setting the MySQL server variable "wait_timeout" to some high value rather than the default of 8 hours. | false | 1.1 |
| autoReconnectForPools | Use a reconnection strategy appropriate for connection pools (defaults to 'false') | false | 3.1.3 |
| failOverReadOnly | When failing over in autoReconnect mode, should the connection be set to 'read-only'? | true | 3.0.12 |
| maxReconnects | Maximum number of reconnects to attempt if autoReconnect is true, default is '3'. | 3 | 1.1 |
| reconnectAtTxEnd | If autoReconnect is set to true, should the driver attempt reconnections at the end of every transaction? | false | 3.0.10 |
| retriesAllDown | When using loadbalancing, the number of times the driver should cycle through available hosts, attempting to connect. Between cycles, the driver will pause for 250ms if no servers are available. | 120 | 5.1.6 |
| initialTimeout | If autoReconnect is enabled, the initial time to wait between re-connect attempts (in seconds, defaults to '2'). | 2 | 1.1 |
| roundRobinLoadBalance | When autoReconnect is enabled, and failoverReadonly is false, should we pick hosts to connect to on a round-robin basis? | false | 3.1.2 |
| queriesBeforeRetryMaster | Number of queries to issue before falling back to master when failed over (when using multi-host failover). Whichever condition is met first, 'queriesBeforeRetryMaster' or 'secondsBeforeRetryMaster' will cause an attempt to be made to reconnect to the master. Defaults to 50. | 50 | 3.0.2 |
| secondsBeforeRetryMaster | How long should the driver wait, when failed over, before attempting | 30 | 3.0.2 |
| selfDestructOnPingMaxOperations | =If set to a non-zero value, the driver will report close the connection and report failure when Connection.ping() or Connection.isValid(int) is called if the connnection's count of commands sent to the server exceeds this value. | 0 | 5.1.6 |
| selfDestructOnPingSecondsLifetime | If set to a non-zero value, the driver will report close the connection and report failure when Connection.ping() or Connection.isValid(int) is called if the connnection's lifetime exceeds this value. | 0 | 5.1.6 |
| resourceId | A globally unique name that identifies the resource that this datasource or connection is connected to, used for XAResource.isSameRM() when the driver can't determine this value based on hostnames used in the URL | 5.0.1 |
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原文地址：MySQL JDBC中autoReconnectForPools的用途, 感谢原作者分享。
