Last packet sent to the server was 0 ms ago.

異常以下

org.springframework.dao.RecoverableDataAccessException: PreparedStatementCallback; SQL []; Communications link failure

Last packet sent to the server was 0 ms ago.; nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 0 ms ago.
	at org.springframework.jdbc.support.SQLExceptionSubclassTranslator.doTranslate(SQLExceptionSubclassTranslator.java:98)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:72)
	at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:80)
	at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:603)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:637)
	at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:662)
	at net.paoding.rose.jade.dataaccess.DataAccessImpl.select(DataAccessImpl.java:55)
	at net.paoding.rose.jade.statement.SelectQuerier.execute(SelectQuerier.java:63)
	at net.paoding.rose.jade.statement.SelectQuerier.execute(SelectQuerier.java:56)
	at net.paoding.rose.jade.statement.JdbcStatement.execute(JdbcStatement.java:146)
	at net.paoding.rose.jade.statement.cached.CachedStatement.execute(CachedStatement.java:98)
	at net.paoding.rose.jade.context.JadeInvocationHandler.invoke(JadeInvocationHandler.java:128)
	at com.sun.proxy.$Proxy8.getSubjectNoQualify(Unknown Source)
	at com.chaoxing.subject.service.SubjectService.getSubjectNoQualify(SubjectService.java:189)
	at com.chaoxing.subject.jobs.SubjectJobFromKafka.run(SubjectJobFromKafka.java:60)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Last packet sent to the server was 0 ms ago.
	at sun.reflect.GeneratedConstructorAccessor71.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2985)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2871)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3414)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1936)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2060)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
	at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1885)
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:2714)
	at com.alibaba.druid.wall.WallFilter.preparedStatement_executeQuery(WallFilter.java:603)
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:2711)
	at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_executeQuery(FilterEventAdapter.java:465)
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:2711)
	at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_executeQuery(FilterEventAdapter.java:465)
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_executeQuery(FilterChainImpl.java:2711)
	at com.alibaba.druid.proxy.jdbc.PreparedStatementProxyImpl.executeQuery(PreparedStatementProxyImpl.java:132)
	at com.alibaba.druid.pool.DruidPooledPreparedStatement.executeQuery(DruidPooledPreparedStatement.java:227)
	at org.springframework.jdbc.core.JdbcTemplate$1.doInPreparedStatement(JdbcTemplate.java:644)
	at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:587)
	... 11 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
	at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2431)
	at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2882)
	... 29 more

緣由：

因爲MySQL服務在長時間（默認8小時）不鏈接超時了，因此個人Java程序數據庫鏈接池中的全部鏈接都是不可用的，但Java程序分辨不了（須要配置屬性在解決方法中說明）認爲鏈接可用，這時若是有用戶請求訪問就會如上異常。這就是異常的緣由

兩種解決辦法：

1 、配置MySQL屬性wait_timeout=(配一個大的時間)

二、 配置testOnBorrow和validationQuery每次檢測鏈接是否可用

<property name=」minEvictableIdleTimeMillis」 value=」1800000″ />
<property name=」numTestsPerEvictionRun」 value=」3″ />
<property name=」testOnBorrow」 value=」true」 />
<property name=」testWhileIdle」 value=」true」 />
<property name=」testOnReturn」 value=」true」 />
<property name=」validationQuery」 value=」SELECT 1″ />