[INFO] imooc-security ..................................... SUCCESS [  0.002 s]

[INFO] imooc-security-core ................................ SUCCESS [  2.153 s]

[INFO] imooc-security-app ................................. SUCCESS [  0.069 s]

[INFO] imooc-security-browser ............................. SUCCESS [  0.061 s]

[INFO] imooc-security-demo ................................ FAILURE [  1.770 s]

[INFO] ------------------------------------------------------------------------

[INFO] BUILD FAILURE

[INFO] ------------------------------------------------------------------------

[INFO] Total time: 4.377 s

[INFO] Finished at: 2017-12-28T17:33:47+08:00

[INFO] Final Memory: 25M/283M

[INFO] ------------------------------------------------------------------------

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.2:war (default-war) on project imooc-security-demo: Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode) -> [Help 1]