问题：maven构建工程时报错webxml attribute is required
错误信息：
[INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode)
说明：
In general, for a Java-based Maven project, non-source files should go in the src/main/resourcessub-directory of the project. The contents of that resources directory are copied to the output directory (by default, target/classes) during the process-resources phase of the build.
For Maven WAR projects, it is slightly more complicated: there is also the src/main/webapp directory, wherein Maven expects to find WEB-INF/web.xml. To build your WAR file, that file must exist; otherwise, you'll see an error message like that:
As the WEB-INF directory must exist under src/main/webapp, I'd recommend avoiding defining it again in src/main/resources. Although this is perfectly valid and the contents of the two directories will be merged, it can get confusing if a file is defined in both. The contents of src/main/resourceswill take precedence as they are copied over the top of the contents from src/main/webapp.
解决方案：
在WEB-INF/web.xml中增加一个web.xml用于占位
