关于报错“More than one fragment with the name [spring_web] was found. This is not legal ...”的解决办法

最近在搭建一个spring mvc 项目时遇到“More than one fragment with the name [spring_web] was found. This is not legal ...”报错，详细的日志信息如下：

……
五月 08, 2019 11:49:52 下午 org.apache.catalina.core.ContainerBase startInternal
严重: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:872)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1423)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1413)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    ... 6 more
Caused by: java.lang.IllegalArgumentException: More than one fragment with the name [spring_web] was found. This is not legal with relative ordering. See section 8.2.2 2c of the Servlet specification for details. Consider using absolute ordering.
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2200)
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2159)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1124)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5134)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

五月 08, 2019 11:49:52 下午 org.apache.catalina.core.ContainerBase startInternal
严重: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:793)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:688)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:353)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:493)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1423)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1413)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:872)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
    ... 8 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    ... 6 more
Caused by: java.lang.IllegalArgumentException: More than one fragment with the name [spring_web] was found. This is not legal with relative ordering. See section 8.2.2 2c of the Servlet specification for details. Consider using absolute ordering.
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2200)
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2159)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1124)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5134)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

五月 08, 2019 11:49:52 下午 org.apache.catalina.startup.Catalina start
严重: The required Server component failed to start so Tomcat is unable to start.
org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:688)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:353)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:493)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:793)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 7 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:422)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 9 more
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:262)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 11 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
    ... 13 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1423)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1413)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:872)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at java.util.concurrent.FutureTask.report(FutureTask.java:122)
    at java.util.concurrent.FutureTask.get(FutureTask.java:192)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
    ... 8 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Chapter14]]
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)
    ... 6 more
Caused by: java.lang.IllegalArgumentException: More than one fragment with the name [spring_web] was found. This is not legal with relative ordering. See section 8.2.2 2c of the Servlet specification for details. Consider using absolute ordering.
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2200)
    at org.apache.tomcat.util.descriptor.web.WebXml.orderWebFragments(WebXml.java:2159)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1124)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:769)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:94)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5134)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

五月 08, 2019 11:49:52 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler ["http-nio-8080"]
五月 08, 2019 11:49:52 下午 org.apache.coyote.AbstractProtocol pause
信息: Pausing ProtocolHandler ["ajp-nio-8009"]
五月 08, 2019 11:49:52 下午 org.apache.catalina.core.StandardService stopInternal
信息: Stopping service [Catalina]
五月 08, 2019 11:49:52 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler ["http-nio-8080"]
五月 08, 2019 11:49:52 下午 org.apache.coyote.AbstractProtocol destroy
信息: Destroying ProtocolHandler ["ajp-nio-8009"]

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添加代码<absolute-ording />

这是多个片段重复的原因

来源：CSDN
原文：https://blog.csdn.net/PursueExcellence/article/details/89981690
版权声明：本文为博主原创文章，转载请附上博文链接！

<absolute-ording />这句话是什么意思呢，表示绝对顺序

Web框架的可插入性 
我们前面说过了Servlet3.0的改进之一就是使得我们能够将框架和库插入到web应用程序中。这种可插入性减少了配置，并且提高了web应用程序的模块化。Servlet3.0是通过web模块布署描述片段（简称web片段）来实现插入性的。 
一个web片段就是web.xml文件的一部分，被包含在框架特定的Jar包的META-INF目录中。Web片段使得该框架组件逻辑上就是web应用程序的一部分，不需要编辑web布署描述文件。 
Web片段中使用的元素和布署文件中使用的元素基本相同，除了根元素不一样。Web片段的根元素是<web-fragment>,而且文件名必须叫做web-fragment.xml。容器只会在放在WEB-INF\lib目录下的Jar包中查找web-fragment.xml文件。如果这些Jar包含有web-fragment.xml文件，容器就会装载需要的类来处理他们。 
在web.xml中，我们要求Servlet的name必须唯一。同样的，在web.xml和所有的web片段中，Servlet的name也必须唯一。 
下面就是一个web-fragment的例子： 
web-fragment.xml

1. <web-fragment>

2. <servlet>

3. <servlet-name>ControllerServlet</servlet-name>

4. <servlet-class>com.app.control.ControllerServlet</servlet-class>

5. </servlet>

6. <listener>

7. <listener-class>com.listener.AppServletContextListener</listener-class>

8. </listener>

9. </web-fragment>

复制代码

框架的Jar包是放在WEB-INF\lib目录下的，但是Servlet3.0提供两种方法指定多个web片段之间的顺序： 
   1. 绝对顺序 
   2. 相对顺序 
我们通过web.xml文件中的<absolute-ordering>元素来指定绝对顺序。这个元素有之元素name，name的值是各个web片段的name元素的值。这样就指定了web片段的顺序。如果多个web片段有相同的名字，容器会忽略后出现的web片段。下面是一个指定绝对顺序的例子： 
web.xml

1. <web-app>

2. <name>DemoApp</name>

3. <absolute-ordering>

4. <name>WebFragment1</name>

5. <name>WebFragment2</name>

6. </absolute-ordering>

7. ...

8. </web-app>

复制代码

相对顺序通过web-fragment.xml中的<ordering>元素来确定。Web片段的顺序由<ordering>的子元素<before>,<after>和<others>来决定。当前的web片段会放在所有的<before>元素中的片段之前。同样的，会放在所有的<after>元素中的片段之后。<others>用来代替所有的其他片段。注意只有当web.xml中没有<absolute-ordering>时，容器才会使用web片段中定义的相对顺序。 
下面是一个帮助理解相对顺序的例子： 
web-fragment.xml

1. <web-fragment>

2. <name>WebFragment1</name>

3. <ordering><after>WebFragment2</after></ordering>

4. ...

5. </web-fragment>

复制代码

web-fragment.xml

1. <web-fragment>

2. <name>WebFragment2</name>

3. ..

4. </web-fragment>

复制代码

web-fragment.xml

1. <web-fragment>

2. <name>WebFragment3</name>

3. <ordering><before><others/></before></ordering>

复制代码

.. 
</web-fragment> 
这些文件将会按照下面的顺序被处理： 
   1. WebFragment3 
   2. WebFragment2 
   3. WebFragment1 
包含WebFragment3的Jar文件被最先处理，包含WebFragment2的文件被第二个处理，包含WebFragment1的文件被最后处理。 
如果既没有定义绝对顺序，也没有定义相对顺序，那么容器就认为所有的web片段间没有顺序上的依赖关系。 
Servlet中的异步处理 
很多时候Servlet要和其他的资源进行互动，例如访问数据库，调用web service。在和这些资源互动的时候，Servlet不得不等待数据返回，然后才能够继续执行。这使得Servlet调用这些资源的时候阻塞。Servlet3.0通过引入异步处理解决了这个问题。异步处理允许线程调用资源的时候不被阻塞，而是直接返回。AsyncContext负责管理从资源来的回应。AsyncContext决定该回应是应该被原来的线程处理还是应该分发给容器中其他的资源。AsyncContext有一些方法如start，dispatch和complete来执行异步处理。 
要想使用Servlet3.0的异步处理，我们需要设置@Webservlet和@WebFilter注解的asyncSupport属性。这个属性是布尔值，缺省值是false。 
Servlet3.0的异步处理可以很好的和AJAX配合。在Servlet的init方法中，我们能够访问数据库或从JMS读取消息。在doGet或doPost方法中，我们能够启动异步处理，AsyncContext会通过AsyncEvent和AsyncListener来管理线程和数据库操作/JMS操作自己的关系。