首页 \ 问答 \ 无法打开JPA EntityManager进行事务[...]无法获取驱动程序类“null”和URL“null”的连接(Could not open JPA EntityManager for transaction […] A connection could not be obtained for driver class “null” and URL “null”)

无法打开JPA EntityManager进行事务[...]无法获取驱动程序类“null”和URL“null”的连接(Could not open JPA EntityManager for transaction […] A connection could not be obtained for driver class “null” and URL “null”)

 我在Tomcat 7上托管的基于Spring的Web应用程序中连接到我的数据库时遇到问题。在我寻找解决方案的过程中，我发现很多人遇到过类似的问题，但他们的解决方案似乎都不适合我。 我正在开发Eclipse（RAD 8.5）。  
 这是堆栈跟踪：  
2015-05-18_13:36:49.625 [http-bio-8080-exec-3] ERROR c.m.g.s.TenancyDetailsServiceImpl - Error condition: Could not open JPA EntityManager for transaction; nested exception is <openjpa-2.3.0-r422266:1540826 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: There were errors initializing your configuration: <openjpa-2.3.0-r422266:1540826 fatal user error> org.apache.openjpa.util.UserException: A connection could not be obtained for driver class "null" and URL "null".  You may have specified an invalid URL.
at org.apache.openjpa.jdbc.schema.DataSourceFactory.newConnectException(DataSourceFactory.java:255)
at org.apache.openjpa.jdbc.schema.DataSourceFactory.installDBDictionary(DataSourceFactory.java:241)
at org.apache.openjpa.jdbc.conf.JDBCConfigurationImpl.getConnectionFactory(JDBCConfigurationImpl.java:733)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.apache.openjpa.lib.conf.ConfigurationImpl.instantiateAll(ConfigurationImpl.java:310)
at org.apache.openjpa.conf.OpenJPAConfigurationImpl.instantiateAll(OpenJPAConfigurationImpl.java:1670)
at org.apache.openjpa.kernel.AbstractBrokerFactory.makeReadOnly(AbstractBrokerFactory.java:651)
at org.apache.openjpa.kernel.AbstractBrokerFactory.newBroker(AbstractBrokerFactory.java:203)
at org.apache.openjpa.kernel.DelegatingBrokerFactory.newBroker(DelegatingBrokerFactory.java:155)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:226)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:153)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:59)
at org.springframework.orm.jpa.JpaTransactionManager.createEntityManagerForTransaction(JpaTransactionManager.java:445)
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:366)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:196)
at com.sun.proxy.$Proxy56.getTransaction(Unknown Source)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:336)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at com.sun.proxy.$Proxy39.getTenancyDetailsWithTenantCode(Unknown Source)
at com.m.gsp.serviceimpl.TenancyDetailsServiceImpl.getTenancyDetailsWithTenantCode(TenancyDetailsServiceImpl.java:70)
at com.m.gsp.helper.TenancyDelegate.getTenancyDetailsWithTenantCode(TenancyDelegate.java:42)
at com.m.gsp.utils.WebUtils.fetchTenancyDetails(WebUtils.java:609)
at com.m.gsp.controllers.AuthenticationController.renderLoginPage(AuthenticationController.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at com.m.gsp.tenancy.TenantDispatcherServlet.service(TenantDispatcherServlet.java:101)
at com.m.gsp.tenancy.TenantDispatcherServletProxy.service(TenantDispatcherServletProxy.java:82)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at com.m.gsp.logging.MDCServletFilter.doFilter(MDCServletFilter.java:140)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:186)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at com.m.gsp.tenancy.security.TenantDelegatingFilterProxy.doFilter(TenantDelegatingFilterProxy.java:65)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1176)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:795)
 
 引起：org.apache.tomcat.dbcp.dbcp.SQLNestedException：无法为连接URL'jdbc：sqlserver：AX-RISCVMSQL74 \ SQL74：1435; databaseName =创建类'com.microsoft.sqlserver.jdbc.SQLServerDriver'的JDBC驱动程序GSPVN;” org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory（BasicDataSource.java:1452）org.apache.tomcat.dbcp.BasicDataSource.createDataSource（BasicDataSource.java:1371）atg.apache.tomcat.dbcp .dbcp.BasicDataSource.getConnection（BasicDataSource.java:1044）org.apache.openjpa.lib.jdbc.DelegatingDataSource.getConnection（DelegatingDataSource.java:116）atg.apache.openjpa.lib.jdbc.DecoratingDataSource.getConnection（DecoratingDataSource） .java：93）at org.apache.openjpa.jdbc.schema.DataSourceFactory.installDBDictionary（DataSourceFactory.java:233）... 84更多引起：java.sql.SQLException：java.sql.DriverManager上没有合适的驱动程序。 getDriver（DriverManager.java:289）at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory（BasicDataSource.java:1437）... 89更多  
 context.xml中：  
<Resource name="jdbc/salesvietnamMssqlGspDS"
auth="Container"
factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory"
driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
type="javax.sql.DataSource"
maxActive="50"
maxIdle="10"
maxWait="15000"
username="x"
password="y"
url="jdbc:sqlserver:server/instance:port;databaseName=dbname;"
removeAbandoned="true"
removeAbandonedTimeout="30"
logAbandoned="true" /> 
 
 应用程序的WEB-INF / web.xml：  
<resource-ref>
<description>JDBCconnection</description>
<res-ref-name>jdbc/salesvietnamMssqlGspDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
 
 
 我甚至将相同的resource-ref放在服务器的web.xml中。  
 sqljdbc4.jar存在于服务器的/lib目录中。 我将它添加到运行配置菜单中的用户条目下的Classpath中。 我甚至尝试在构建路径和部署程序集中添加它，我已经验证它确实显示在WEB-INF / lib中。  
 以上都没有任何影响。  
 我读到需要使用Class.forName("something.jdbc.driver.YourFubarDriver");注册驱动程序Class.forName("something.jdbc.driver.YourFubarDriver"); 但后来我也读到了不再需要JDBC4。  
 有任何想法吗？ 

I'm having an issue connecting to my DB in a Spring based web application hosted on Tomcat 7. In my search for a solution I've found many people who have had similar issues but none of their solutions seem to work for me. I'm developing in Eclipse (RAD 8.5). 
Here is the stack trace: 
2015-05-18_13:36:49.625 [http-bio-8080-exec-3] ERROR c.m.g.s.TenancyDetailsServiceImpl - Error condition: Could not open JPA EntityManager for transaction; nested exception is <openjpa-2.3.0-r422266:1540826 nonfatal general error> org.apache.openjpa.persistence.PersistenceException: There were errors initializing your configuration: <openjpa-2.3.0-r422266:1540826 fatal user error> org.apache.openjpa.util.UserException: A connection could not be obtained for driver class "null" and URL "null".  You may have specified an invalid URL.
at org.apache.openjpa.jdbc.schema.DataSourceFactory.newConnectException(DataSourceFactory.java:255)
at org.apache.openjpa.jdbc.schema.DataSourceFactory.installDBDictionary(DataSourceFactory.java:241)
at org.apache.openjpa.jdbc.conf.JDBCConfigurationImpl.getConnectionFactory(JDBCConfigurationImpl.java:733)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.apache.openjpa.lib.conf.ConfigurationImpl.instantiateAll(ConfigurationImpl.java:310)
at org.apache.openjpa.conf.OpenJPAConfigurationImpl.instantiateAll(OpenJPAConfigurationImpl.java:1670)
at org.apache.openjpa.kernel.AbstractBrokerFactory.makeReadOnly(AbstractBrokerFactory.java:651)
at org.apache.openjpa.kernel.AbstractBrokerFactory.newBroker(AbstractBrokerFactory.java:203)
at org.apache.openjpa.kernel.DelegatingBrokerFactory.newBroker(DelegatingBrokerFactory.java:155)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:226)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:153)
at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:59)
at org.springframework.orm.jpa.JpaTransactionManager.createEntityManagerForTransaction(JpaTransactionManager.java:445)
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:366)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:196)
at com.sun.proxy.$Proxy56.getTransaction(Unknown Source)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:336)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at com.sun.proxy.$Proxy39.getTenancyDetailsWithTenantCode(Unknown Source)
at com.m.gsp.serviceimpl.TenancyDetailsServiceImpl.getTenancyDetailsWithTenantCode(TenancyDetailsServiceImpl.java:70)
at com.m.gsp.helper.TenancyDelegate.getTenancyDetailsWithTenantCode(TenancyDelegate.java:42)
at com.m.gsp.utils.WebUtils.fetchTenancyDetails(WebUtils.java:609)
at com.m.gsp.controllers.AuthenticationController.renderLoginPage(AuthenticationController.java:128)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:619)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at com.m.gsp.tenancy.TenantDispatcherServlet.service(TenantDispatcherServlet.java:101)
at com.m.gsp.tenancy.TenantDispatcherServletProxy.service(TenantDispatcherServletProxy.java:82)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at com.m.gsp.logging.MDCServletFilter.doFilter(MDCServletFilter.java:140)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:186)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at com.m.gsp.tenancy.security.TenantDelegatingFilterProxy.doFilter(TenantDelegatingFilterProxy.java:65)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1176)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:795)
 
Caused by: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class 'com.microsoft.sqlserver.jdbc.SQLServerDriver' for connect URL 'jdbc:sqlserver:AX-RISCVMSQL74\SQL74:1435;databaseName=GSPVN;' at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044) at org.apache.openjpa.lib.jdbc.DelegatingDataSource.getConnection(DelegatingDataSource.java:116) at org.apache.openjpa.lib.jdbc.DecoratingDataSource.getConnection(DecoratingDataSource.java:93) at org.apache.openjpa.jdbc.schema.DataSourceFactory.installDBDictionary(DataSourceFactory.java:233) ... 84 more Caused by: java.sql.SQLException: No suitable driver at java.sql.DriverManager.getDriver(DriverManager.java:289) at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1437) ... 89 more 
Context.xml: 
<Resource name="jdbc/salesvietnamMssqlGspDS"
auth="Container"
factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory"
driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
type="javax.sql.DataSource"
maxActive="50"
maxIdle="10"
maxWait="15000"
username="x"
password="y"
url="jdbc:sqlserver:server/instance:port;databaseName=dbname;"
removeAbandoned="true"
removeAbandonedTimeout="30"
logAbandoned="true" /> 
 
Application's WEB-INF/web.xml: 
<resource-ref>
<description>JDBCconnection</description>
<res-ref-name>jdbc/salesvietnamMssqlGspDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
 
 
I even put the same resource-ref in the server's web.xml as well. 
sqljdbc4.jar is present in the server's /lib directory. I added it to the Classpath under user entries in the run configurations menu. I even tried adding it in the build path and deployment assembly, I've verified it does show up in WEB-INF/lib. 
None of the above have had any effect. 
I read about needing to register the driver using Class.forName("something.jdbc.driver.YourFubarDriver"); but then I also read that was no longer necessary with JDBC4. 
Any ideas?

原文：https://stackoverflow.com/questions/30311285

更新时间：2023-02-03 13:02

最满意答案

 您需要在代码中包含一些头文件：  
 
  unordered_map使用unordered_map STL。 而且，您只能在C ++ 11和C ++ 14中使用它。  
  vector使用矢量STL。  
  algorithm使用内置的sort（）函数。  
 
 还有一些错误：  
 
  函数的名称是MakeSet() ，你使用Makeset()调用它  
  您在for(Edge e: g.edges){}循环中使用了roo2而不是root2  
  for(Edge e: A){}循环中的cout语句在语法上不正确。  

There are a few header files you need to include in your code:  
 
 unordered_map to use the unordered_map STL. Moreover, you can use it only in C++11 and C++14.  
 vector to use the vector STL.  
 algorithm to use the inbuilt sort() function.  
 
A few more bugs:  
 
 The name of the function is MakeSet(), and you're calling it using Makeset() 
 You have used roo2 instead of root2 in your for(Edge e: g.edges){} loop 
 The cout statement in your for(Edge e: A){} loop is not syntactically correct.

无法打开JPA EntityManager进行事务[...]无法获取驱动程序类“null”和URL“null”的连接(Could not open JPA EntityManager for transaction […] A connection could not be obtained for driver class “null” and URL “null”)

最满意答案

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