解决The content of element type "w

错误：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)".

• No grammar constraints (DTD or XML schema) detected for the document.
  web.xml头部配置：

< xml version="1.0" encoding="UTF-8" >
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "">
<web-app>

原因：文档内容标签顺序不符合web-app_2_3.dtd规范

解决方案

1：严格按照提示上的顺序排列

2：删除<!DOCTYPE 。。。。这段内容