后台tomcat启动错误提示：

2012-08-01 18:34:09,567 ERROR [org.hibernate.util.JDBCExceptionReporter] - Cannot load JDBC driver class 'org.postgresql.Driver'

前台页面执行时后台报错：

2012-08-01 18:36:47,642 ERROR [org.hibernate.util.JDBCExceptionReporter] - Cannot load JDBC driver class 'org.postgresql.Driver'
   2012-08-01 18:36:47,642 ERROR [org.hibernate.util.JDBCExceptionReporter] - Cannot load JDBC driver class 'org.postgresql.Driver'
   2012-8-1 18:36:47 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet jsp threw exception
java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class org.postgresql.Driver)
	at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1854)
	at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:890)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1354)
	at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233)
	at java.lang.ClassLoader.loadClassInternal(Unknown Source)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Unknown Source)
	at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1130)
	at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)
	at org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:82)
	at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
	at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
	at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
	at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1573)
	at org.hibernate.loader.Loader.doQuery(Loader.java:696)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
	at org.hibernate.loader.Loader.doList(Loader.java:2228)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2125)
	at org.hibernate.loader.Loader.list(Loader.java:2120)
	at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401)
	at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:361)
	at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1148)
	at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
	at com.tintek.dao.impl.LoginInfoDaoImpl.findAll(LoginInfoDaoImpl.java:37)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy8.findAll(Unknown Source)
	at com.tintek.service.impl.LoginInfoServiceImpl.findAllInfo(LoginInfoServiceImpl.java:31)
	at org.apache.jsp.testdb_jsp._jspService(testdb_jsp.java:98)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
	at java.lang.Thread.run(Unknown Source)

环境：

jdk1.6.0_18+MyEclipse6.5+apache-tomcat-6.0.20

Struts1.3+Spring2.5+Hibernate3+Postgresql9.0

分析：

检查了一下我的MyEclipse6.5配置，发现在MyEclipse里面给Tomcat 配置的JDK是其默认的MyEclipse6.5.

解决：

在myEclipse中修改编译器版本：

Window->Preferences...->MyEclipse Enterprise Workbench->Servers->Tomcat->Tomcat 6.x->JDK

在这个界面可以看到jdk原来默认是MyEclipse6.5自带的版本。

单击右边的“Add...”按钮添加我们装在本机的jdk1.6

在上图中选择了jdk1.6安装目录下的jre6目录，然后ok就可以了。

在上面第一幅图中选择新添加的Tomcat JDK name--------------jre6

确定之后，重新编译项目，ok，问题解决。