如何在GWT中覆盖EntityLocator的isLive

时间：2012-12-07 06:31:15

标签： gwt requestfactory

我是GWT的新手，我在项目中将GWT与spring框架集成在一起。 模块页面包括两个部分：LeftSide（树视图）和RightPanel（gridview）。 我从数据库（Department，Employee）构建了treeview节点。 Gridview用于在从树视图中选择节点时显示结果。问题是当我打开网址（http://127.0.0.1:8888/ams.html?gwt.codesvr=127.0.0.1:9997），有时，树视图没有显示任何内容，并在控制台上打印以下例外。但是正确的gridview是可以的。如果我覆盖EntityLocator的isLive（只返回true）方法，那么它总是正常

javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: could not load an entity: [com.sparj.ams.server.domain.staff.Department#50001]
    at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1214)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:635)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:589)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:365)
    at $Proxy31.find(Unknown Source)
    at com.sparj.ams.server.locator.EntityLocator.find(EntityLocator.java:47)
    at com.sparj.ams.server.locator.EntityLocator.find(EntityLocator.java:1)
    at com.google.web.bindery.requestfactory.shared.Locator.isLive(Locator.java:96)
    at com.google.web.bindery.requestfactory.server.LocatorServiceLayer.doIsLive(LocatorServiceLayer.java:188)
    at com.google.web.bindery.requestfactory.server.LocatorServiceLayer.isLive(LocatorServiceLayer.java:85)
    at com.google.web.bindery.requestfactory.server.ServiceLayerDecorator.isLive(ServiceLayerDecorator.java:116)
    at com.google.web.bindery.requestfactory.server.ServiceLayerDecorator.isLive(ServiceLayerDecorator.java:116)
    at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.createReturnOperations(SimpleRequestProcessor.java:282)
    at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:240)
    at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:135)
    at com.google.web.bindery.requestfactory.server.RequestFactoryServlet.doPost(RequestFactoryServlet.java:133)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1097)
    at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:147)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1088)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)
Caused by: org.hibernate.exception.JDBCConnectionException: could not load an entity: [com.sparj.ams.server.domain.staff.Department#50001]
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
    at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2041)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:86)
    at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:76)
    at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3268)
    at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:496)
    at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:477)
    at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:227)
    at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:285)
    at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
    at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1090)
    at org.hibernate.impl.SessionImpl.get(SessionImpl.java:1005)
    at org.hibernate.impl.SessionImpl.get(SessionImpl.java:998)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:614)
    ... 41 more
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after statement closed.
    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:525)
    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.StatementImpl.checkClosed(StatementImpl.java:463)
    at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:3783)
    at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:3832)
    at com.mysql.jdbc.PreparedStatement.setLong(PreparedStatement.java:3849)
    at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.setLong(NewProxyPreparedStatement.java:703)
    at org.hibernate.type.descriptor.sql.BigIntTypeDescriptor$1.doBind(BigIntTypeDescriptor.java:52)
    at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:89)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:282)
    at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:277)
    at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1873)
    at org.hibernate.loader.Loader.bindParameterValues(Loader.java:1844)
    at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1716)
    at org.hibernate.loader.Loader.doQuery(Loader.java:801)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
    at org.hibernate.loader.Loader.loadEntity(Loader.java:2037)
    ... 53 more

1 个答案:

答案 0 :(得分：2)

问题不在于isLive，而是你管理Hibernate会话生命周期的方式：在调用isLive之前会话以某种方式关闭。

使用RequestFactory，您拥有来使用session-per-http-request（又名OpenSessionInView）模式。

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