報錯資訊：

java.sql.SQLException: Access denied for user 'Administrator'@'localhost' (using password: YES)

嚴重: create connection SQLException, url: jdbc:mysql://localhost:3306/db2?&useSSL=false&serverTimezone=UTC, errorCode 1045, state 28000
java.sql.SQLException: Access denied for user 'Administrator'@'localhost' (using password: YES)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835)
    at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:455)
    at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240)
    at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1644)
    at com.alibaba.druid.pool.DruidAbstractDataSource.createPhysicalConnection(DruidAbstractDataSource.java:1710)
    at com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:2753)

明明密碼對的，被拒絕了，找了好久原因，後來發現將db.properties配置檔案裡的username改為jdbc.username就好了，可能是因為username被系統變數佔用了。
當spring容器在進行啟動的時候，會讀取當前系統某些環境變數的配置，當前系統的使用者名稱使用username來表示的，所以做好的方式是新增字首，使用jdbc.username.

jdbc.username=root
jdbc.password=root
jdbc.url=jdbc:mysql://localhost:3306/db2?&useSSL=false&serverTimezone=UTC
jdbc.driverClassName=com.mysql.cj.jdbc.Driver

轉： https://www.cnblogs.com/tyhA-nobody/p/13166892.html