[WARNING] 
[WARNING] Some problems were encountered while building the effective settings
[WARNING] expected START_TAG or END_TAG not TEXT (position: TEXT seen ...\n\t\t     http://localhost:8081/nexus/content/groups/public/\n\t    <u... @177:8)  @ C:\soft\apache-maven-3.5.2\conf\settings.xml, line 177, column 8
 

[WARNING] expected START_TAG or END_TAG not TEXT (position: TEXT seen ...\n\t\t     http://localhost:8081/nexus/content/groups/public/\n\t    <u... @177:8)  @ C:\soft\apache-maven-3.5.2\conf\settings.xml, line 177, column 8
[WARNING] 
[INFO] Scanning for projects...
[ERROR] [ERROR] Some problems were encountered 
 
while processing the POMs:
[ERROR] 'packaging' with value 'war' is invalid. Aggregator projects require 'pom' as packaging. @ line 9, column 16
 @ 
[ERROR] The build could not read 1 project -> [Help 1]
[ERROR]   
[ERROR]   The project com.guigu.emp:emp2:1.0-SNAPSHOT (E:\S3\Spring\day89_�ۺϹ���01andMaven�߼�\emp2\pom.xml) has 1
 
 error
[ERROR]     'packaging' with value 'war' is invalid. Aggregator projects require 'pom' as packaging. @ line 9, column 16
[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/ProjectBuildingException
Disconnected from the target VM, address: '127.0.0.1:55112', transport: 'socket'

Process finished with exit code 1

這個是因為你專案是一個webapp工程，

必須是一個pom

最後就成功了