tomcat7,hibernate 4,struts 2,再次找不到合适的驱动程序

Question

我正在一个基于struts framework 2.3.3和tomcat 7.0.26的项目中使用hibernate 4.1.2。我还使用mysql（和postgres）进行测试。这是我使用MySQL的hibernate.cfg.xml：

<session-factory>

  <property name="c3p0.min_size">5</property>
  <property name="c3p0.max_size">20</property>
  <property name="c3p0.timeout">300</property>
  <property name="c3p0.max_statements">50</property>
  <property name="c3p0.idle_text_period">3000</property>

  <property name="show_sql">true</property>

  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="connection.url">jdbc:mysql://localhost/struts2</property>
  <property name="connection.username">semperEst</property>
  <property name="connection.password">*******</property>
  <property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</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">create-drop</property>

  <mapping class="firstname.secondname.lesson2.User"/>

</session-factory>

我的WEB-INF/LIB包含：

antlr-2.7.7.jar

asm-3.3.jar

asm-commons-3.3.jar

asm-tree-3.3.jar

commons-fileupload-1.2.2.jar

commons-io-2.0.1.jar

commons-lang-2.4.jar

commons-lang3-3.1.jar

dom4j-1.6.1.jar

freemarker-2.3.19.jar

hibernate-commons-annotations-4.0.1.Final.jar 

hibernate-core-4.1.2.Final.jar

hibernate-jpa-2.0-api-1.0.1.Final.jar

javassist-3.11.0.GA.jar

javassist-3.15.0-GA.jar

jboss-logging-3.1.0.GA.jar

jboss-transaction-api_1.1_spec-1.0.0.Final.jar

log4j-1.2.16.jar

mysql-connector-java-5.1.20-bin.jar

ognl-3.0.5.jar

postgresql-9.1-902.jdbc4.jar

slf4j-api-1.6.4-sources.jar

slf4j-log4j12-1.6.4.jar

struts2-core-2.3.3.jar

xwork-core-2.3.3.jar

*我已经在$CATALINA_HOME/lib*中添加了mysql-connector-java-5.1.20-bin.jar

    at java.sql.DriverManager.getConnection(DriverManager.java:190)

    at  org.hibernate.service.jdbc.connections.internal.
       DriverManagerConnectionProviderImpl.
       getConnection(DriverManagerConnectionProviderImpl.java:192) 

    at org.hibernate.internal.
       AbstractSessionImpl$NonContextualJdbcConnectionAccess.
       obtainConnection(AbstractSessionImpl.java:278)

    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.
       obtainConnection(LogicalConnectionImpl.java:297)

    at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.
       getConnection(LogicalConnectionImpl.java:169)

    at org.hibernate.engine.transaction.internal.
       jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:67)

    at org.hibernate.engine.transaction.spi.
       AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160)

    at org.hibernate.internal.SessionImpl.
       beginTransaction(SessionImpl.java:1363)

    at firstname.lastname.lesson2.
       PortfolioService.usernameExists(PortfolioService.java:122)

    at firstname.lastname.lesson2.CreateUser.validate(CreateUser.java:255)

    at com.opensymphony.xwork2.validator.ValidationInterceptor.
       doBeforeInvocation(ValidationInterceptor.java:251)

    at com.opensymphony.xwork2.validator.ValidationInterceptor.
       doIntercept(ValidationInterceptor.java:263)

    at org.apache.struts2.interceptor.validation.
       AnnotationValidationInterceptor.
       doIntercept(AnnotationValidationInterceptor.java:68)
at 
     .
     .
     .(struts activation frame...)
     .
     at org.apache.catalina.core.ApplicationFilterChain.
        internalDoFilter(ApplicationFilterChain.java:243)

     at org.apache.catalina.core.ApplicationFilterChain.
        doFilter(ApplicationFilterChain.java:210)

     at org.apache.catalina.core.StandardWrapperValve.
       invoke(StandardWrapperValve.java:224)

     at org.apache.catalina.core.StandardContextValve.
        invoke(StandardContextValve.java:169)

      at org.apache.catalina.authenticator.AuthenticatorBase.
        invoke(AuthenticatorBase.java:472)

      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)

      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)

      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)

      at org.apache.catalina.core.StandardEngineValve.
         invoke(StandardEngineValve.java:118)

      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)

      at org.apache.coyote.http11.AbstractHttp11Processor.
          process(AbstractHttp11Processor.java:987)

      at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.
         process(AbstractProtocol.java:579)

      at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.
         run(JIoEndpoint.java:307)

      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)

      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)

      at java.lang.Thread.run(Thread.java:722)

提前致谢

Answer 1

当这种事情发生时（“找不到合适的驱动程序”），通常的问题是您的JDBC库不是在错误的地方（取决于您的需求），就是在太多的地方（比如在WEB-INF/lib中，以及在容器的lib/目录中）。

哪个组件实际上在创建您的JDBC连接池？如果是Tomcat（情况似乎并非如此），那么您的mysql.jar需要在Tomcat的lib/目录中（特别是不在WebApp的web-inf/lib目录中）。如果您在webapp中进行所有操作，那么您可能希望mysql.jar位于webapp中的web-inf/lib中，而/而不是/位于Tomcat的lib目录中。

如果您有多个WebApp，并且其中一些正在使用Tomcat的DataSource配置，那么最好将mysql.jar放入Tomcat的lib/目录中，并将其从所有webapps的WEB-INF/lib目录中删除。