Eclipse, deploying the project to Tomcat, reported the following error, meaning that Tomcat failed to start, the project is introduced such as the project. I checked my maven configuration, and the settings.xml pointing is fine. Baidu checked to see a lot of answers are not effective. And finally I see a similar problem which is the following. There are a lot of comments below his post and there are no effective answers. Finally, I saw that he himself, inspired by others, added the warehouse address of Ali Cloud in settings. XML and deleted the local library from the update project below. I think it is OK for me to re-download the warehouse, because I introduced some old dependencies that may conflict with the existing warehouse dependencies. Finally, the problem was effectively solved.
Remind yourself to change settings.xml. Be careful not to copy too much or delete a bit of the comment in the source file or Eclips will post a Code Not Read Settings error in the User Settings section. Remember to install maven first, love you mua, bye!

nexus-aliyun
*
Nexus aliyun
http://maven.aliyun.com/nexus/content/groups/public

[INFO] Scanning for projects...
[INFO] 
[INFO] --------------------------< com.lzh:TestSSM1 >--------------------------
[INFO] Building TestSSM1 Maven Webapp 0.0.1-SNAPSHOT
[INFO] --------------------------------[ war ]---------------------------------
[INFO] 
[INFO] >>> tomcat7-maven-plugin:2.2:run (default-cli) > process-classes @ TestSSM1 >>>
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ TestSSM1 ---
[INFO] Using 'utf-8' encoding to copy filtered resources.
[INFO] Copying 18 resources
[INFO] Copying 2 resources
[INFO] 
[INFO] --- maven-compiler-plugin:2.3.2:compile (default-compile) @ TestSSM1 ---
[INFO] Nothing to compile - all classes are up to date
[INFO] 
[INFO] <<< tomcat7-maven-plugin:2.2:run (default-cli) < process-classes @ TestSSM1 <<<
[INFO] 
[INFO] 
[INFO] --- tomcat7-maven-plugin:2.2:run (default-cli) @ TestSSM1 ---
[INFO] Downloading from central: https://repo.maven.apache.org/maven2/junit/junit/4.10/junit-4.10.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3.198 s
[INFO] Finished at: 2018-07-10T14:57:35+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.tomcat.maven:tomcat7-maven-plugin:2.2:run (default-cli) on project TestSSM1: Execution default-cli of goal org.apache.tomcat.maven:tomcat7-maven-plugin:2.2:run failed: Plugin org.apache.tomcat.maven:tomcat7-maven-plugin:2.2 or one of its dependencies could not be resolved: Failed to collect dependencies at org.apache.tomcat.maven:tomcat7-maven-plugin?2.2  [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginResolutionException