手机简洁记账软件排行:关于servlet，我的tomcat怎么总是显示500

HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Error allocating a servlet instance
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:175)
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:207)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:647)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:497)
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:575)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:649)
java.lang.Thread.run(Unknown Source)

root cause

java.lang.UnsupportedClassVersionError: mySession/ShowItems (Unsupported major.minor version 49.0)
java.lang.ClassLoader.defineClass0(Native Method)
java.lang.ClassLoader.defineClass(Unknown Source)
java.security.SecureClassLoader.defineClass(Unknown Source)
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1656)
org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:891)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1340)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1220)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:175)
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:207)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:647)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:497)
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:575)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:649)
java.lang.Thread.run(Unknown Source)

note The full stack trace of the root cause is available in the Tomcat logs.

是不是我的tomcat有毛病了？我在别的机器上调试好的程序在我的电脑上怎么总是显示上面的东西？
不是一个代码的问题，是所有的代码全是这样的．我在别的机器上弄好的，很正常，可是一到我的机器是就出现上面的情况．我的tomcat是5.0版的．别的用的是4.0吧好象．可是以前我用着也行，为什么现在不行了？
下面是代码：
哎呀不行 代码百度不让贴，有点长