環境：ubuntu 18.04

mysql:5.7.30

nacos:1.1.4

nacos連線異常提示:

org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNested    Exception: Cannot create PoolableConnectionFactory (Could not create connection to database server. Attempted reconnect 3 times. Giving up.)
 33     at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:81).....
.............
............
Caused by: org
 
.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Could not create connection to database server. At    tempted reconnect 3 times. Giving up.)
117     at org.apache.commons.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549)
118     at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388)                                                        
119     at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
120     at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:151)
121     at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:115)
122     at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:78)
123     ... 82 more
 
124 Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconne    ct 3 times. Giving up.
125     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)....
............
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
 
152 
153 The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
154     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
155     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
156     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
157     at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
158     at com.mysql.jdbc.Util.handleNewInstance(Util.java:377)
159     at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1036)
160     at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:338)
161     at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2232)
162     at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2085)
163     ... 101 more
164 Caused by: java.net.ConnectException: Connection refused (Connection refused)....
.......

網上查了各種方法都沒用，最後還以是不是自己的mysql有問題，因為ubuntu安裝mysql時是沒有讓輸入密碼的，所以root不用密碼也能登入。

然後嘗試建立新使用者nacos，開放所有許可權，還是沒用。

最後給root新增，設定密碼，然後用root連結，問題解決!

修改root使用者的的密碼如下：

這裡是關鍵點，由於mysql5.7沒有password欄位，密碼儲存在authentication_string欄位中，password()方法還能用

在mysql中執行下面語句修改密碼

show databases； 
use mysql; 
update user set authentication_string=PASSWORD("yourpassword") where user='root'; 
update user set plugin="mysql_native_password"; 
flush privileges; 
quit;