如果连接在spring jpa中关闭，如何重新连接数据库？

Question

我使用弹簧启动，弹簧JPA中，MySQL在我的web application.When我的应用程序运行一段时间，我总是有以下情况除外：

2016-07-30 21:27:12.434 ERROR 13553 --- [http-nio-8090-exec-8] o.h.engine.jdbc.spi.SqlExceptionHelper : No operations allowed after connection closed. 
2016-07-30 21:27:12.434 WARN 13553 --- [http-nio-8090-exec-5] o.h.engine.jdbc.spi.SqlExceptionHelper : SQL Error: 0, SQLState: 08003 
2016-07-30 21:27:12.434 ERROR 13553 --- [http-nio-8090-exec-5] o.h.engine.jdbc.spi.SqlExceptionHelper : No operations allowed after connection closed. 
2016-07-30 21:27:12.438 ERROR 13553 --- [http-nio-8090-exec-8] [.[.[.[.c.c.Go2NurseJerseyConfiguration] : Servlet.service() for servlet [com.cooltoo.config.Go2NurseJerseyConfiguration] in context with path [] threw exception [org.springframework.dao.DataAccessResourceFailureException: could not prepare statement; nested exception is org.hibernate.exception.JDBCConnectionException: could not prepare statement] with root cause 

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:3119) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3570) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3559) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4110) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2570) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2815) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2322) ~[mysql-connector-java-5.1.25.jar!/:na] 
     at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:82) ~[hibernate-core-4.3.11.Final.jar!/:4.3.11.Final] 

我已经检查数据库运行良好。发生这种情况时，我必须重新启动弹簧引导应用程序。我如何检查问题是什么？为什么数据库连接关闭？如果发生这种情况，我是否可以重新连接数据库？ 下面是我application.properties：

spring.datasource.url=jdbc:mysql://192.168.99.100:3306/test?characterEncoding=utf8 
spring.datasource.username=admin 
spring.datasource.password=123456 
spring.datasource.driver-class-name=com.mysql.jdbc.Driver 
spring.datasource.max-active=150 

Answer 1

这似乎是与MySQL一个常见的错误。

1）添加到您的application.properties，看看它是如何去：

spring.datasource.testOnBorrow=true 
spring.datasource.validationQuery=SELECT 1 

testOnBorrow在spring doc这other stackoverflow question详述。然而，我无法在Spring的文档中找到关于validationQuery的参考，但它似乎有诀窍。

2）或者，您也可以使用testWhileIdle这里建议http://christoph-burmeister.eu/?p=2849

他建议说给你的application.properties：

spring.datasource.testWhileIdle = true 
spring.datasource.validationQuery = SELECT 1 

该解决方案还mentionned在其他计算器问题，这只是不被接受的答案，但似乎是一些解决方案。

3）在这种情况下，他们还增加了timeBetweenEvictionRunsMillis：

spring.datasource.testWhileIdle = true 
spring.datasource.validationQuery = SELECT 1 
spring.datasource.timeBetweenEvictionRunsMillis = 3600000 

编辑：另一个stackoverflow question覆盖此（一个非常完整的答案）