maven在使用tomcat插件tomcat7-maven-plugin:2.2:run运行项目,出现下面错误:

严重: A child container failed during start

java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]]

...

Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]]

    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)

    ... 6 more

Caused by: java.lang.LinkageError: loader constraint violation: loader (instance of org/apache/catalina/loader/WebappClassLoader) previously initiated loading for a different type with name "javax/servlet/ServletContext"

...

Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost]]

    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)

    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)

    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)

    at java.util.concurrent.FutureTask.run(FutureTask.java:262)

    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)

    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)

    at java.lang.Thread.run(Thread.java:745)

Caused by: org.apache.catalina.LifecycleException: A child container failed during start

解决方案:

将下面的依赖包从项目中删掉,因为这个servlet-api版本太低了.删掉这个依赖包,直接启动项目,如果可以启动,那就没什么问题.

<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>servlet-api</artifactId>
  <version>2.5</version>
</dependency>

如果删除servlet-api提示缺少servlet-api包里的类,那就在maven仓库中找到最新版本的包,添加到pom.xml中.

或者

在idea中, File -> Project Structure ->Module -> 找到项目 ->Dependencies -> 点击右侧 "+"  -> Library..-> 拉到最底下 ->Application Server Libraries -> 添加一个tomcat的依赖.