tomcat報錯：org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. 

關於一個HTTP頭驗證出錯的問題：

org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. Could not load [META-INF/services/javax.xml.stream.XMLInputFactory]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [META-INF/services/javax.xml.stream.XMLInputFactory]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.

意思是：

org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading非法訪問：此web應用程序實例已停止。無法加載[META-INF/services/javax.xml.stream.XMLInputFactory]。為了調試以及終止導致非法訪問的線程，將拋出以下堆棧跟蹤。

java.lang.IllegalStateException:非法訪問：此web應用程序實例已停止。無法加載[META-INF/services/javax.xml.stream.XMLInputFactory]。為了調試以及終止導致非法訪問的線程，將拋出以下堆棧跟蹤。

此處產生問題的原因是：一個tomcat啟動了兩個進程。

為什么會產生兩個進程呢？ 在網上找了一大堆資料后，大致說法如下：

1、sh shutdown.sh
不能完全殺死tomcat或者是不能立馬殺死tomcat
2、tomcat的con/server.xml中的context屬性reloadable默認為true導致。

由於windows環境下，Tomcat被占用是會自動彈窗報錯的，此時若關掉窗口在重啟tomcat是可以再運行項目的，但由此就會引發這個一個tomcat開兩個進程的問題，進而導致URL出錯等問題。

解決方法是：關掉占用端口的進程即可。