• MySQL連接8小時，沒有請求，則斷開連接。報錯如下：

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 51,000,697 milliseconds ago.  The last packet sent successfully to the server was 51,000,698 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.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:989)
    at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3746)
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2509)
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680)
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2487)
    at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858)
    at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1966)
    at sun.reflect.GeneratedMethodAccessor22.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.tomcat.jdbc.pool.StatementFacade$StatementProxy.invoke(StatementFacade.java:114)
    at com.sun.proxy.$Proxy57.executeQuery(Unknown Source)
    at org.springframework.jdbc.core.JdbcTemplate$1.doInPreparedStatement(JdbcTemplate.java:692)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:633)
    ... 42 common frames omitted
Caused by: java.net.SocketException: 斷開的管道 (Write failed)
    at java.net.SocketOutputStream.socketWrite0(Native Method)
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
    at java.net.SocketOutputStream.write(SocketOutputStream.java:155)
    at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
    at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
    at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3728)
    ... 54 common frames omitted

• 解決辦法：application.properties中加入以下配置

#驗證連接的有效性
master.spring.datasource.test-while-idle=true
#獲取連接時候驗證，會影響性能
master.spring.datasource.test-on-borrow=true
master.spring.datasource.validation-query=SELECT 1 FROM DUAL
#空閑連接回收的時間間隔，與test-while-idle一起使用，設置5分鐘
master.spring.datasource.time-between-eviction-runs-millis=300000
#連接池空閑連接的有效時間 ，設置30分鐘
master.spring.datasource.min-evictable-idle-time-millis=1800000

• 參考帖子

spring boot mysql 8小時連接超時