title: How to reconnect database if the connection closed in spring jpa?
body: <p>I am using spring-boot, spring-jpa, mysql in my web application.When my application is running for some hours, I always got below exceptions:</p>
  
  <pre><code>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]
  </code></pre>
  
  <p>I have checked that the database is running well. I have to restart my spring-boot application when that happened. How can I check what the problem is? Why the database connection got closed? If that happened, whether I can re-connect the database?
  Below is my application.properties:</p>
  
  <pre><code>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
  </code></pre>