1. Log in to the website below, download the Demo project (chapter 4-5-1), and import the maven project into eclipse
https://gitee.com/didispace/SpringBoot-Learning
2. Configure the application.properties file
3. Log in to the QQ mailbox to obtain the authorization code
Settings--"Account--"Generate Authorization Code
4. Change the code in the project and set it to your own email address
5. Run ApplicationTests.java