【Tomcat】热部署的遗留配置导致服务器无法启动

1、问题描述：
今天用myeclipse写了个小demo，然后用Tomcat7 部署了，接着点击启动服务器，服务器居然报错：
[align=left]严重: Error starting static Resources[/align]
[align=left]java.lang.IllegalArgumentException: Document base H:\software\apache-tomcat\apache-tomcat-7.0.52\webapps\lemon does not exist or is not a readable directory[/align]
[align=left] at org.apache.naming.resources.FileDirContext.setDocBase(FileDirContext.java:136)[/align]
[align=left] at org.apache.catalina.core.StandardContext.resourcesStart(StandardContext.java:5089)[/align]
[align=left] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5269)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)[/align]
[align=left] at java.util.concurrent.FutureTask.run(FutureTask.java:262)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[/align]
[align=left] at java.lang.Thread.run(Thread.java:745)[/align]
[align=left]四月 22, 2017 6:57:41 下午 org.apache.catalina.core.ContainerBase startInternal[/align]
[align=left]严重: A child container failed during start[/align]
[align=left]java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/lemon]][/align]
[align=left] at java.util.concurrent.FutureTask.report(FutureTask.java:122)[/align]
[align=left] at java.util.concurrent.FutureTask.get(FutureTask.java:188)[/align]
[align=left] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)[/align]
[align=left] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:799)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)[/align]
[align=left] at java.util.concurrent.FutureTask.run(FutureTask.java:262)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[/align]
[align=left] at java.lang.Thread.run(Thread.java:745)[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/lemon]][/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)[/align]
[align=left] ... 6 more[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: Error in resourceStart()[/align]
[align=left] at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5270)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] ... 6 more[/align]
[align=left]四月 22, 2017 6:57:41 下午 org.apache.catalina.core.ContainerBase startInternal[/align]
[align=left]严重: A child container failed during start[/align]
[align=left]java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]][/align]
[align=left] at java.util.concurrent.FutureTask.report(FutureTask.java:122)[/align]
[align=left] at java.util.concurrent.FutureTask.get(FutureTask.java:188)[/align]
[align=left] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123)[/align]
[align=left] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:731)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] at org.apache.catalina.startup.Catalina.start(Catalina.java:689)[/align]
[align=left] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)[/align]
[align=left] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)[/align]
[align=left] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)[/align]
[align=left] at java.lang.reflect.Method.invoke(Method.java:606)[/align]
[align=left] at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:321)[/align]
[align=left] at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]][/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)[/align]
[align=left] at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)[/align]
[align=left] at java.util.concurrent.FutureTask.run(FutureTask.java:262)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[/align]
[align=left] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[/align]
[align=left] at java.lang.Thread.run(Thread.java:745)[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: A child container failed during start[/align]
[align=left] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)[/align]
[align=left] at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:799)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] ... 6 more[/align]
[align=left]四月 22, 2017 6:57:41 下午 org.apache.catalina.startup.Catalina start[/align]
[align=left]严重: The required Server component failed to start so Tomcat is unable to start.[/align]
[align=left]org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]][/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)[/align]
[align=left] at org.apache.catalina.startup.Catalina.start(Catalina.java:689)[/align]
[align=left] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)[/align]
[align=left] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)[/align]
[align=left] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)[/align]
[align=left] at java.lang.reflect.Method.invoke(Method.java:606)[/align]
[align=left] at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:321)[/align]
[align=left] at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:455)[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]][/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)[/align]
[align=left] at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:731)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] ... 7 more[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]][/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)[/align]
[align=left] at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]
[align=left] ... 9 more[/align]
[align=left]Caused by: org.apache.catalina.LifecycleException: A child container failed during start[/align]
[align=left] at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131)[/align]
[align=left] at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:300)[/align]
[align=left] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)[/align]

... 11 more
2、问题分析：
Document base H:\software\apache-tomcat\apache-tomcat-7.0.52\webapps\lemon does not exist or is not a
这句话告诉我们在tomcat的webapps下找不到lemon这个项目 看了看 确实没有.



此时，我能想到的就是work这个临时文件夹，一般出错都是这个临时文件夹搞的鬼，但是delete掉后，问题依旧。



思来想去，想起了eclipse的workspace下的.metadata下的plugins内的插件org.eclipse.wst.server.core下有个配置文件servers.xml是指定部署项目的相关配置.



于是，我就想myeclipse一般是部署在真实的tomcat上，应该会修改 tomcat的配置文件，因此我找到了tomcat的配置文件server.xml



打开发现，



3、问题解决：
查了下context标签的意思，原来，
<!-- tomcat配置的虚拟路径 docBase="应用的实际目录" 如果用myclipse编写 则是webRoot Tomcat热部署 -->
<!-- <Context docBase="lemon" path="/lemon" reloadable="true" source="org.eclipse.jst.j2ee.server:lemon"/> -->
最后，我分析可能是因为我们在用myeclipse开发时，由于某种误操作导致myeclipse没有及时去更新server.xml配置文件，导致遗留了一些无效配置。
删掉最后的那句<!-- <Context docBase="lemon" path="/lemon" reloadable="true" source="org.eclipse.jst.j2ee.server:lemon"/> -->，服务器正常启动!