mysql重連，連接丟失：The last packet successfully received from the server

1.1 錯誤信息：

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 20,820,001 milliseconds ago.  The last packet sent successfully to the server was 20,820,002 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.
		at sun.reflect.GeneratedConstructorAccessor29.newInstance(Unknown Source) ~[na:na]
		at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.7.0_51]
		at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[na:1.7.0_51]
		at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1129) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3988) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2598) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2828) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5372) ~[mysql-connector-java-5.1.29.jar:na]
		at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:881) ~[c3p0-0.9.1.1.jar:0.9.1.1]
		at org.quartz.impl.jdbcjobstore.AttributeRestoringConnectionInvocationHandler.setAutoCommit(AttributeRestoringConnectionInvocationHandler.java:98) ~[quartz-2.2.1.jar:na]

1.2 解決方法

- 如果使用的是JDBC，在JDBC URL上添加?autoReconnect=true，如：

jdbc:mysql://10.10.10.10:3306/mydb?autoReconnect=true

- 如果是在Spring中使用DBCP連接池，在定義datasource增加屬性validationQuery和testOnBorrow，如：

<bean id="vrsRankDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName" value="${jdbc.driverClassName}" />
    <property name="url" value="${countNew.jdbc.url}" />
    <property name="username" value="${countNew.jdbc.user}" />
    <property name="password" value="${countNew.jdbc.pwd}" />
    <property name="validationQuery" value="SELECT 1" />
    <property name="testOnBorrow" value="true"/>
</bean>

- 如果是在Spring中使用c3p0連接池，則在定義datasource的時候，添加屬性testConnectionOnCheckin和testConnectionOnCheckout，如：

<bean name="cacheCloudDB" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <property name="driverClass" value="${jdbc.driver}"/>
    <property name="jdbcUrl" value="${cache.url}"/>
    <property name="user" value="${cache.user}"/>
    <property name="password" value="${cache.password}"/>
    <property name="initialPoolSize" value="10"/>
    <property name="maxPoolSize" value="${cache.maxPoolSize}"/>
    <property name="testConnectionOnCheckin" value="false"/>
    <property name="testConnectionOnCheckout" value="true"/>
    <property name="preferredTestQuery" value="SELECT 1"/>
</bean>