How can the Maven settings configuration file take effect?

In order for the Maven settings configuration file to take effect, it needs to be placed in the correct location and configured accordingly based on the situation.

1. Locate the settings.xml file. By default, it can be found in the conf folder of the Maven installation directory. On Windows, it might be in C:\Program Files\Apache Maven\conf\settings.xml; on Linux or Mac OS X, it could be in /usr/share/maven/conf/settings.xml or /usr/local/apache-maven/conf/settings.xml.
2. Edit the settings.xml file. As needed, you can configure the following options in the file:
3. Set the local repository path for Maven by locating the node and setting its value to the path of the local repository. For example: /path/to/local/repository.
4. Configure remote repository: Locate the section, then add a section underneath it to set up the URL, id, and mirrorOf attributes for the remote repository. For example:
5. 
   central
   http://maven.aliyun.com/nexus/content/groups/public/
   central
   

   This is a mirror configuration for the central repository with the ID “central” pointing to the URL “http://maven.aliyun.com/nexus/content/groups/public/”.

6. Configure the proxy server: Locate the node, add a node underneath it, and enter the host, port, username, and password for the proxy server. For example:
7. proxy
   true http proxy.example.com 8080 proxyuser proxypassword localhost|127.0.0.1
8. “Save and close the settings.xml file.”
9. Set up system variables. Add a variable named MAVEN_HOME in the environment variables, and set its value to the installation directory of Maven. For example: C:\Program Files\Apache Maven.
10. Set up the PATH variable by adding %MAVEN_HOME%\bin to it, so that you can directly execute the mvn command in the command line.
11. Restart the command line terminal or IDE and run the ‘mvn’ command to verify if the configuration has taken effect. If the configuration is correct, Maven’s version information will be displayed.

Please note that if a custom settings.xml file is used in the project, it needs to be placed in the project’s root directory and its location should be specified in the command line or IDE. For example, you can specify using the file in the command line with mvn -s /path/to/settings.xml.