- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
我有一个 J2EE 应用程序,它使用 JSP 页面作为前端,使用 Struts2 作为 Controller 。我还使用 Hibernate 将我的对象映射到 MySql 数据库中。当我在服务器上部署应用程序时,它工作正常,但在不可预知的时间段(如 1 或两天)之后,无论我在哪里使用 hibernate 查询,我都会不断收到此错误:
org.hibernate.exception.JDBCConnectionException: could not execute query
更有趣的是,当这种情况发生时,并不是 100% 的查询都以这个异常结束!有时其中一些会被正确执行。
发生错误的代码示例:
public synchronized static Player getPlayerByID(String playerID) throws NoSuchPlayer {
Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();
Player player = (Player) session.createQuery(
"from Player as player where player.loginName = '" + playerID
+ "'").uniqueResult();//THE ERROR HAPPENS HERE
session.getTransaction().commit();
if (player == null)
throw new NoSuchPlayer();
return player;
}
这是各自的堆栈跟踪:
'org.hibernate.exception.JDBCConnectionException: could not execute query
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.loader.Loader.doList(Loader.java:2297)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:448)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1258)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:859)
at com.hposg.domain.HPOSG.getPlayerByID(HPOSG.java:117)
at com.hposg.login.UserSession.getPlayerById(UserSession.java:39)
at com.hposg.controller.struts.BuyAction.execute(BuyAction.java:74)
at sun.reflect.GeneratedMethodAccessor1098.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:636)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.Connection was implicitly closed due to underlying exception/error:
** BEGIN NESTED EXCEPTION **
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException
MESSAGE: Communications link failure
Last packet sent to the server was 0 ms ago.
STACKTRACE:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
Last packet sent to the server was 0 ms 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:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:353)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2583)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2871)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1601)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1710)
at com.mysql.jdbc.Connection.execSQL(Connection.java:2436)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1402)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1556)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1849)
at org.hibernate.loader.Loader.doQuery(Loader.java:718)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:448)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1258)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at com.hposg.domain.HPOSG.getGameList(HPOSG.java:222)
at com.hposg.controller.struts.GamesLoadActionAjax.execute(GamesLoadActionAjax.java:23)
at sun.reflect.GeneratedMethodAccessor1047.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:636)
Caused by: java.io.EOFException
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1958)
at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2372)
... 83 more
** END NESTED EXCEPTION **
at sun.reflect.GeneratedConstructorAccessor139.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:353)
at com.mysql.jdbc.Util.getInstance(Util.java:336)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:985)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:957)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
at com.mysql.jdbc.Connection.checkClosed(Connection.java:1103)
at com.mysql.jdbc.Connection.prepareStatement(Connection.java:3865)
at com.mysql.jdbc.Connection.prepareStatement(Connection.java:3831)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:534)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:452)
at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1596)
at org.hibernate.loader.Loader.doQuery(Loader.java:717)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
... 74 more
'
最后这是我的 hibernate 配置文件:
<?xml version='1.0' encoding='utf-8'?>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">
jdbc:mysql://localhost/hposg?characterEncoding=UTF-8
</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>
<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>
<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>
<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>
<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">update</property>
<!-- Mapping files -->
<mapping resource="com/hposg/hibernate/resources/Player.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Game.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Portfolio.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Purchase.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Sale.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Message.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Admin.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/News.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Invitation.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/CustomGameCreationRequest.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Alert.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/AlertLimits.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/StockIndex.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/HPOSG.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Tradeable.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/GlobalGameConfig.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/Announcement.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/AdviserMsg.hbm.xml"/>
<mapping resource="com/hposg/hibernate/resources/SystemConfiguration.hbm.xml"/>
</session-factory>
顺便说一句,我没有使用 c3p0 连接池,我不知道这是否相关。只是觉得提一下。
有什么想法吗?
最佳答案
Hibernate uses a primitive connection pooling mechanism ,这不适合生产目的(它甚至在日志文件中说!)。您应该始终使用连接池机制,无论是您的容器提供的机制,还是捆绑在您的应用程序中的机制(例如 c3p0)。您看到的异常是因为 MySQL 关闭了 Hibernate 仍在使用的“旧”连接。您可以尝试添加一个 JDBC URL 选项,例如“autoReconnect”,但这确实不是一个长期的解决方案。
理想情况下,您应该配置您的容器以通过 JNDI 为您的应用程序提供连接。这可以通过 JBoss 中的“-ds.xml”文件或 Tomcat 的 context.xml 轻松完成。
关于java - 继续获取 org.hibernate.exception.JDBCConnectionException : could not execute query,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5218663/
有时我一直在努力理解为什么在尝试创建航路点任务时任务管理器会收到错误“无法执行执行”。我附上了我正在使用的工作流程,如果您能看一下,我将不胜感激。 1.Initialize FlightControl
我正在 Python 中使用 SQLAlchemy 核心,并且我已多次阅读文档,但仍然需要有关 engine.execute() 的说明。与 connection.execute() . 据我了解,e
在我的 Zend 框架项目中,我想检查是否设置了 cookie。如果是这种情况,我想使用 cookie 内容登录用户。 由于我必须在调用任何 Controller 之前执行此自动登录,因此我尝试将其放
我正在尝试为我创建的 2 个选择语句的 UNION 创建一个 View 。 UNION 在单独执行时工作正常 但问题是当我将它作为 View 执行时,只有 UNION 的第一部分被执行。 我正在使用的
下面我写了一个简单的例子来演示我遇到的问题。执行代码后,我得到一个 cygwin 异常 7200。我环顾四周并尝试了一些事情,但没有解决。有人可以解释为什么我得到它,我该如何解决?感谢您抽出宝贵时间,
从池中获取连接然后在连接上调用 execute 而不是直接在池对象上调用 execute 的用例是什么? 在 Pool 的文档中类,显示此示例: con = await pool.acquire()
我正在尝试通过 SQL 将变量中的 2 个值插入表中,代码完成时没有错误,但条目未显示在表中。 我尝试在即时窗口中执行代码,但这给了我一个关于括号的错误(我真的不知道如何在那里正确输入提示),所以我将
我对广播接收器有点困惑。我有一个广播接收器,它在 TIME_SET 和 TIMEZONE_CHANGED 操作时触发(代码在下面给出)。我想知道的是,当 TIME_SET 和 TIMEZONE_CHA
我必须与需要随每个请求发送访问 token 的外部服务集成。访问 token 的到期时间很短(只有几个小时)。我决定以乐观的方式使用访问 token 。我将使用当前 token 调用外部服务。如果出现
如果我在 swift 中运行以下代码,步骤 1.、2.、3. 和 4. 是否始终按此顺序执行(它们应该如此),或者如果循环存在异步执行的风险,排序等,花费的时间比预期的要长? // 1. fo
我在我的 C++ 应用程序中看到访问冲突错误。在发生违规并使用 !analyze 时将 windbg 附加到进程时,我发现访问违规是由于试图执行不可执行的地址。我知道导致此问题的正在执行的地址。什么可
在使用 Ubuntu 大约一年之后,这对我来说是第一次。 我接手了一个跟踪维修的汽车服务项目。我可以看到每个文件的完整源代码,但是有一个没有扩展名的文件,但在 Ubuntu 中,属性显示为可执行文件(
什么是 LinqPad“自动跟踪执行”和“跳转到执行点”?如何使用它们,如果你能给出一个详细的例子将不胜感激。 最佳答案 这不是一个详细的示例,但它说明了该功能。如果你有一个像 "1".Dump()
我使用 Q.js 来实现 promise 。在下面的代码中,每个方法都会进行 ajax 调用,然后返回一个 Promise。一切都按预期进行,每个方法在下一个方法开始之前执行并完成: function
我有一个类,它实现了 Runnable接口(interface),并且是一个一旦启动就会无限期运行的任务(长时间运行的线程)。 public class LongRunningTask impleme
PDOStatement::execute() [pdostatement.execute]: SQLSTATE[HY093]: 无效的参数数量:绑定(bind)变量的数量与标记数量不匹配 我收到此错
关闭。这个问题是not reproducible or was caused by typos .它目前不接受答案。 这个问题是由于错别字或无法再重现的问题引起的。虽然类似的问题可能是on-topi
想要为执行的每个 linux 命令添加 aspect:executionTime 有什么方法可以添加默认方面环境,以便必须为执行的 linux 命令获取 executionTime 最佳答案 根据 m
我正在尝试安装一个名为 MFOC 的工具.我按照其网站中提到的说明进行操作,如下所示: ebrahim@ubuntu:~$ cd Desktop/mfoc-master/ ebrahim@ubuntu
我刚开始使用 numba 来提高我的程序的性能。我已经减少了我将要呈现的情况 import numba as nb import numpy as np from time import time d
我是一名优秀的程序员,十分优秀!