我在Google的App Engine上运行了一个Java应用程序，但我在连接数据库时失败了。我相信这个问题之前肯定已被问过多次，但我找不到任何对我有用的东西。我已经广泛使用了persistence.xml文件，我确信这是我的问题所在，但我看不到它。
错误日志显示：
org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions: An SQLException was provoked by the following failure: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup") (SqlExceptionHelper.java:144)
com.mycompany.rfc.web.servlet.ProcessServlet doGet: Problem with servlet operation (ProcessServlet.java:356)
javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Could not open connection
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1387)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1310)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:273)
at com.mycompany.rfc.data.dao.dbimpl.RfcAccess.getAllOpenForUser(RfcAccess.java:25)
at com.mycompany.rfc.web.servlet.ProcessServlet.doGet(ProcessServlet.java:192)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:37)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:60)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:48)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:257)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:145)
at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:511)
at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.hibernate.exception.GenericJDBCException: Could not open connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:221)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:157)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:56)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$5.doPrepare(StatementPreparerImpl.java:161)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:182)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareQueryStatement(StatementPreparerImpl.java:159)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1854)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1831)
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1811)
at org.hibernate.loader.Loader.doQuery(Loader.java:899)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
at org.hibernate.loader.Loader.doList(Loader.java:2516)
at org.hibernate.loader.Loader.doList(Loader.java:2502)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2332)
at org.hibernate.loader.Loader.list(Loader.java:2327)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:490)
at org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1268)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:264)
... 36 more
Caused by: java.sql.SQLException: An SQLException was provoked by the following failure: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:62)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.<init>(C3P0PooledConnectionPoolManager.java:228)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getPoolManager(AbstractPoolBackedDataSource.java:460)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:84)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:292)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:214)
... 56 more
Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:484)
at java.security.AccessController.checkPermission(AccessController.java:698)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at com.google.apphosting.runtime.security.CustomSecurityManager.checkPermission(CustomSecurityManager.java:55)
at com.google.apphosting.runtime.security.CustomSecurityManager.checkAccess(CustomSecurityManager.java:136)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.Thread.init(Thread.java:391)
at java.lang.Thread.init(Thread.java:349)
at java.lang.Thread.<init>(Thread.java:445)
at java.util.TimerThread.<init>(Timer.java:499)
at java.util.Timer.<init>(Timer.java:101)
at java.util.Timer.<init>(Timer.java:146)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.poolsInit(C3P0PooledConnectionPoolManager.java:95)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPoolManager.<init>(C3P0PooledConnectionPoolManager.java:221)
... 61 more
我的persistence.xml文件是： http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd“＆GT;
<persistence-unit name="rfcJPA2" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<mapping-file>META-INF/orm.xml</mapping-file>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://<IPaddr>:3306/rfc_db" />
<property name="javax.persistence.jdbc.password" value="<pw>" />
<property name="javax.persistence.jdbc.user" value="<user>" />
<property name="hibernate.transaction.factory_class"
value="org.hibernate.transaction.JDBCTransactionFactory" />
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.hbm2ddl.auto" value="update" />
<property name="hibernate.connection.provider_class"
value="org.hibernate.connection.C3P0ConnectionProvider" />
<property name="hibernate.c3p0.max_size" value="100" />
<property name="hibernate.c3p0.min_size" value="0" />
<property name="hibernate.c3p0.acquire_increment" value="1" />
<property name="hibernate.c3p0.idle_test_period" value="300" />
<property name="hibernate.c3p0.timeout" value="100" />
</properties>
</persistence-unit>
我可以在本地工作，但在将代码推送到Google Cloud时会遇到异常。我使用MySql客户端使用persistence.xml文件中的IP和凭据附加到数据库。
我尝试过使用MySQLDialect Dialect（目前是MySQL5Dialect）。我目前正在使用Hibernate版本4.2.0.Final，因为我读过后来的版本会产生谷歌禁止的线程。
在堆栈跟踪中，我注释了RfcAccess的第25行。
public class RfcAccess extends Access implements IRfcAccess, IAccess {
public RfcAccess() {
super();
}
@Override
public Map<Long, Rfc> getAllOpenForUser(String user) {
List<?> results = null;
results = em.createNamedQuery("getAllOpenRfcForUser").setParameter("owner", user).getResultList(); // This is line 25
if (results == null) {
return null;
}
...
}
public class Access implements IAccess {
EntityManager em;
public Access() {
em = EMF.get().createEntityManager();
}
public class EMF {
protected static final EntityManagerFactory emfInstance = Persistence
.createEntityManagerFactory("rfcJPA2");
private EMF() {
}
public static EntityManagerFactory get() {
return emfInstance;
}
}
在我的ORM中，我有以下命名查询
<named-query name="getAllOpenRfcForUser">
<query>select o from Rfc o where o.status = 0 and o.owner = :owner</query>
<hint name="org.hibernate.timeout" value="200" />
</named-query>
有人可以对此有所了解吗？目前，表（Rfc）未在数据库中创建。谢谢。
答案 0 :(得分：0)
我最终解决了问题（以及有关App Engine在此过程中的工作方式的学习负载）。事实证明C3P0使用线程 - 而GAE不允许线程。我已经设法使用DBCP来实现这一点。