java - 如果连接在 spring jpa 中关闭，如何重新连接数据库？

Question

我在我的 web 应用程序中使用 spring-boot、spring-jpa、mysql。当我的应用程序运行几个小时时，我总是遇到以下异常:

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]

我已经检查过数据库运行良好。发生这种情况时，我必须重新启动我的 spring-boot 应用程序。我怎样才能检查问题是什么？为什么数据库连接关闭了？如果发生这种情况，我是否可以重新连接数据库？下面是我的 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 MySQL 的常见错误。

1) 将此添加到您的 application.properties 并查看它的运行情况:

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

testOnBorrow 在 spring doc 中有详细说明还有这个other stackoverflow question .然而，我无法在 Spring 的文档中找到关于 validationQuery 的引用，但它似乎可以解决问题。

2) 或者，您可以按照此处的建议使用 testWhileIdle http://christoph-burmeister.eu/?p=2849

他建议将此添加到您的 application.properties:

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

在其他 stackoverflow 问题中也提到了这个解决方案，它只是没有被接受的答案，但似乎是某些人的解决方案。

3) 在这种情况下，他们还添加了timeBetweenEvictionRunsMillis:

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

编辑:另一个 stackoverflow question涵盖了这一点(有一个非常完整的答案)