org.jboss.deployment.DeploymentException: Document root element "web-app"问题解决
在JBOSS整合web项目中，启动时报错。
org.jboss.deployment.DeploymentException: Document root element "web-app",主要还是web.xml的问题，如果在web.xml中没有下面代码
会报出：
org.jboss.deployment.DeploymentException: Document root element "web-app", must match DOCTYPE root "null".; - nested throwable: (org.xml.sax.SAXParseException: Document root element "web-app", must match DOCTYPE root "null".)是因为xml文件没有定义约束的dtd文件导致的，需要添加上。
新添加了上述DTD约束，继续报错如下
org.jboss.deployment.DeploymentException: The content of element type "web-app" must match "(icon?,display-name?,description?,distributable?,context-param*,filter*,filter-mapping*,listener*,servlet*,servlet-mapping*,session-config?,mime-mapping*,welcome-file-list?,error-page*,taglib*,resource-env-ref*,resource-ref*,security-constraint*,login-config?,security-role*,env-entry*,ejb-ref*,ejb-local-ref*)".; - nested throwable: (org.xml.sax.SAXParseException: The content of element type "web-app" must match "(icon?,display-name?,description?,distributable?,context-param*,filter*,filter-mapping*,listener*,servlet*,servlet-mapping*,session-config?,mime-mapping*,welcome-file-list?,error-page*,taglib*,resource-env-ref*,resource-ref*,security-constraint*,login-config?,security-role*,env-entry*,ejb-ref*,ejb-local-ref*)".)解决办法在web-app标签中，完全按照上面的顺序配置即可。