java.lang.NoSuchMethodError: javax.servlet.ServletContext.getEffectiveSessionTrackingModes()

最近在把jboss从4.2.2升级到6.0.0时候，遇到各种各样的问题，主要都是类版本冲突，好容易把问题都找出来服务器run起来之前，第一次访问抛出了这个异常

An exception or error occurred in the container during the request processing: java.lang.NoSuchMethodError: javax.servlet.ServletContext.getEffectiveSessionTrackingModes()Ljava/util/Set;
        at org.apache.catalina.connector.CoyoteAdapter.postParseRequest(CoyoteAdapter.java:567)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:359)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951)
        at java.lang.Thread.run(Thread.java:679) [:1.6.0_22]

搜了一下，下面这篇文章讲得比较仔细，果断分享之

http://stackoverflow.com/questions/8969497/java-lang-nosuchmethoderror-javax-servlet-servletcontext-geteffectivesessiont

贴出内容：

java.lang.NoSuchMethodError: javax.servlet.ServletContext.getEffectiveSessionTrackingModes()Ljava/util/Set;

This method is introduced in Servlet 3.0. This error can have at least the following causes:

1. Your web.xml is not declared conform at least Servlet 3.0.

2. Your servlet container does not support at least Servlet 3.0.

3. You have servlet container specific libraries of an older version in /WEB-INF/lib.

To solve this problem,

1. Ensure that your web.xml root declaration conforms Servlet 3.0:

   <?xml version="1.0" encoding="UTF-8"?><web-app     xmlns="http://java.sun.com/xml/ns/javaee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"    version="3.0">    <!-- Config here. --></web-app>

2. Ensure that you're deploying to a Servlet 3.0 compatible container. In case of JBoss AS that would be at least version 6.0.0.

3. Ensure that you don't have those libraries in /WEB-INF/lib. They do not belong there. This is a common beginner's mistake to "solve" compilation errors they faced in their IDE. See also How do I import the javax.servlet API in my Eclipse project?

You've declared your web.xml conform Servlet 2.2. This is definitely wrong. Fix it accordingly.