我正在使用Netbeans和本地Glassfish服务器实例运行Web应用程序。一切都工作正常，但如果我让网站闲置几分钟，然后尝试导航到需要数据库操作的页面，数据库似乎超时。
我没有在persistence.xml或其他任何地方更改任何特定设置。一切都在默认设置下运行。
请注意，我连接的MySQL服务器不是我的服务器。我只能对我的数据库进行写访问，因此我无法更改任何全局MySQL配置文件或任何内容。
从堆栈跟踪看起来像eclipseLink问题，但我不知道如何修复它。
INFO: Communication failure detected when attempting to perform read query outside of a transaction. Attempting to retry query. Error was: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
Error Code: 0
Call: SELECT Reg, Colour, EngineCC, FuelType, ImagePath, IsAvailable, Make, Model, Price, Transmission, Year FROM Vehicle WHERE ((((Make = ?) AND (Transmission = ?)) AND (Price < ?)) AND (IsAvailable = ?))
bind => [4 parameters bound]
Query: ReadAllQuery(referenceClass=Vehicle sql="SELECT Reg, Colour, EngineCC, FuelType, ImagePath, IsAvailable, Make, Model, Price, Transmission, Year FROM Vehicle WHERE ((((Make = ?) AND (Transmission = ?)) AND (Price < ?)) AND (IsAvailable = ?))").
WARNING: Local Exception Stack:
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
Error Code: 0
Call: SELECT Reg, Colour, EngineCC, FuelType, ImagePath, IsAvailable, Make, Model, Price, Transmission, Year FROM Vehicle WHERE ((((Make = ?) AND (Transmission = ?)) AND (Price < ?)) AND (IsAvailable = ?))
bind => [4 parameters bound]
Query: ReadAllQuery(referenceClass=Vehicle sql="SELECT Reg, Colour, EngineCC, FuelType, ImagePath, IsAvailable, Make, Model, Price, Transmission, Year FROM Vehicle WHERE ((((Make = ?) AND (Transmission = ?)) AND (Price < ?)) AND (IsAvailable = ?))")
at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:340)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.processExceptionForCommError(DatabaseAccessor.java:1605)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:671)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:558)
at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:1995)
at org.eclipse.persistence.sessions.server.ServerSession.executeCall(ServerSession.java:570)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:299)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:694)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2714)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2667)
at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:477)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1155)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:899)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1114)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:402)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1202)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2894)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1797)
at org.eclipse.persistence.internal.sessions.AbstractSession.retryQuery(AbstractSession.java:1867)
at org.eclipse.persistence.sessions.server.ClientSession.retryQuery(ClientSession.java:685)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.retryQuery(UnitOfWorkImpl.java:5532)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1833)
at org.eclipse.persistence.internal.sessions.AbstractSession.retryQuery(AbstractSession.java:1867)
at org.eclipse.persistence.sessions.server.ClientSession.retryQuery(ClientSession.java:685)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.retryQuery(UnitOfWorkImpl.java:5532)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1833)
at org.eclipse.persistence.internal.sessions.AbstractSession.retryQuery(AbstractSession.java:1867)
at org.eclipse.persistence.sessions.server.ClientSession.retryQuery(ClientSession.java:685)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.retryQuery(UnitOfWorkImpl.java:5532)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1833)
at org.eclipse.persistence.internal.sessions.AbstractSession.retryQuery(AbstractSession.java:1867)
at org.eclipse.persistence.sessions.server.ClientSession.retryQuery(ClientSession.java:685)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.retryQuery(UnitOfWorkImpl.java:5532)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1833)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1779)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1744)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:468)
at Servlet.SearchServlet.processRequest(SearchServlet.java:66)
at Servlet.SearchServlet.doPost(SearchServlet.java:120)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:724)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.GeneratedConstructorAccessor135.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:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1014)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:988)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:974)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:919)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1290)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1282)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4468)
at com.mysql.jdbc.ConnectionImpl.prepareStatement(ConnectionImpl.java:4434)
at com.sun.gjc.spi.base.ConnectionHolder.prepareStatement(ConnectionHolder.java:514)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.prepareStatement(DatabaseAccessor.java:1551)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.prepareStatement(DatabaseAccessor.java:1500)
at org.eclipse.persistence.internal.databaseaccess.DatabaseCall.prepareStatement(DatabaseCall.java:778)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:619)
... 68 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet successfully received from the server was 303,413 milliseconds ago. The last packet sent successfully to the server was 1 milliseconds ago.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
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:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3603)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3492)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4043)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2794)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2322)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeSelect(DatabaseAccessor.java:1002)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:641)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:558)
at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:1995)
at org.eclipse.persistence.sessions.server.ServerSession.executeCall(ServerSession.java:570)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:299)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:694)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2714)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2667)
at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:477)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1155)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:899)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1114)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:402)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1202)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2894)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1797)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1779)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1744)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:468)
at Servlet.DisplayVehicles.processRequest(DisplayVehicles.java:35)
at Servlet.DisplayVehicles.doGet(DisplayVehicles.java:64)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
... 28 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:3052)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3503)
... 61 more
WARNING: StandardWrapperValve[SearchServlet]: Servlet.service() for servlet SearchServlet threw exception
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:3052)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3503)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3492)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4043)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2794)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2322)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeSelect(DatabaseAccessor.java:1002)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:641)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:558)
at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:1995)
at org.eclipse.persistence.sessions.server.ServerSession.executeCall(ServerSession.java:570)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:299)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:694)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2714)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2667)
at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:477)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:1155)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:899)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:1114)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:402)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1202)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2894)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1797)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1779)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1744)
at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:258)
at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:468)
at Servlet.DisplayVehicles.processRequest(DisplayVehicles.java:35)
at Servlet.DisplayVehicles.doGet(DisplayVehicles.java:64)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:724)
具有数据库查询的典型servlet：
@WebServlet(name = "DisplayVehicles", urlPatterns = {"/Browse"})
public class DisplayVehicles extends HttpServlet {
@PersistenceUnit
private EntityManagerFactory emf;
/** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
assert emf != null; //Make sure injection went through correctly.
EntityManager em = null;
try {
em = emf.createEntityManager();
//query for all the cars in database
List images = em.createQuery("SELECT v FROM Vehicle v WHERE v.imagePath IS NOT NULL AND v.isAvailable=1").getResultList();
request.setAttribute("searchResultsList",images);
//Forward to the jsp page for rendering
request.getRequestDispatcher("Browse.jsp").forward(request, response);
} catch (Exception ex) {
throw new ServletException(ex);
} finally {
//close the em to release any resources held up by the persistence provider
if(em != null) {
em.close();
}
}
}
答案 0 :(得分：0)
基于MySQLNonTransientConnectionException我要打赌，DB上的MySQL wait_timeout变量很短，你正在失去EM试图访问的连接。解决此问题的一种方法是使用Connection pool on your Glassfish server并让它控制DBConnections而不是EclipseLink。作为一个很好的副作用，它应该更具预感性。