部署im-server使用mysql需要修改什么？ 当前修改了config/wildfirechat.conf 中的embed.db 0 启动im-server后报错 com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:829) at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:449) at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:242) at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:677) at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228) at win.liyufan.im.DBUtil.init(DBUtil.java:97) at io.moquette.server.Server.startServer(Server.java:234) at io.moquette.server.Server.startServer(Server.java:226) at io.moquette.server.Server.startServer(Server.java:210) at io.moquette.server.Server.start(Server.java:120) at cn.wildfirechat.server.Server.main(Server.java:15) Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure