在Fedora 8下面运行一个简单的Servlet，出现了下面的错误：[code]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:117)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:834)
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:640)
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1286)
java.lang.Thread.run(Thread.java:675)
root cause
java.lang.UnsupportedClassVersionError: servlet/HelloWorld : Unsupported major.minor version 51.0
java.lang.ClassLoader.defineClass1(Native Method)
java.lang.ClassLoader.defineClass(ClassLoader.java:638)
java.security.SecureClassLoader.defineClass(SecureClassLoader.java:143)
org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1853)
org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:875)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1330)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1209)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:834)
org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:640)
org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1286)
java.lang.Thread.run(Thread.java:675)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.26 logs.[/code]错误原因：Tomcat使用的Java版本与编译Servlet使用的Java版本不一致。
解决方法：在编译时加上参数：-source 1.4 -target 1.4
