mysql-Communications link failure 和SQLException: The server time zone value 'Öйú±ê׼ʱ¼ä' is unreco

现象：在项目启动的时候出现以下信息：

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_181]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_181]
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:990) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.MysqlIO.(MysqlIO.java:342) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2188) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2221) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2016) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.(ConnectionImpl.java:776) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.JDBC4Connection.(JDBC4Connection.java:47) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_181]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_181]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_181]
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_181]
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.46.jar:5.1.46]
	at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386) ~[mysql-connector-java-5.1.46.jar:5.1.46]

使用Connector/J连接MySQL数据库:Communications link failure，The last packet successfully received from the server was *** millisecond ago.The last packet successfully sent to the server was ***  millisecond ago。 这个错误的话，是因为你超过了MySQL的默认闲置时间。

解决方法：把Connetion URL=jdbc:mysql://127.0.0.1:3306/XXX

改成Connetion URL=jdbc:mysql://localhost:3306/XXX

结论：一般而言，默认情况下，root默认只可以通过localhost访问，ip是不可以的，是没有权限，需要修改myslq配置文件。如果数据库和你部署的服务器是用一台机器，那么使用localhost没有问题，要是不在同一台，可能需要改mysql配置，保证ip可以访问。

java.sql.SQLException: The server time zone value 'Öйú±ê׼ʱ¼ä' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:835) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:455) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:240) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:207) ~[mysql-connector-java-8.0.13.jar:8.0.13]
	at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:136) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:369) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:198) ~[HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:467) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:541) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.pool.HikariPool.(HikariPool.java:115) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.2.0.jar:na]
	at com.zaxxer.hikari.HikariDataSource$$FastClassBySpringCGLIB$$eeb1ae86.invoke() [HikariCP-3.2.0.jar:na]
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) [spring-core-5.1.3.RELEASE.jar:5.1.3.RELEASE]
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749) [spring-aop-5.1.3.RELEASE.jar:5.1.3.RELEASE]

 

报错原因：

在使用mysql的jdbc驱动最新版（6.0+）时，遇到数据库和系统时区差异引起的问题。

解决方法0-使用6.0以下版本的jdbc：

降版本，并不推荐；

 

解决方法1-在jdbc url指定默认时区：

还有一种是在jdbc连接的url后面加上serverTimezone=UTC或GMT即可，如果指定使用gmt+8时区，需要写成GMT%2B8，否则可能报解析为空的错误。示例如下：

jdbc.url=jdbc:mysql://localhost:3306/XXX?serverTimezone=UTC

 

解决方法2-在数据库配置中添加默认时区：

方法1（该方法本人未实验成功）：在my.cnf（linux）或者my.ini（win）配置文件[mysqld]底下添加：

default-time-zone = '+8:00' 然后重启数据库服务器即可。

方法2：SQL语句配置全局时区

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone |        |
| time_zone        | SYSTEM |
+------------------+--------+
2 rows in set, 1 warning (0.00 sec)

#设置当前session时区，即时生效，但仅作用于当前session

mysql> set time_zone='+8:00';

Query OK, 0 rows affected (0.00 sec)

#设置全局时区，即时生效，作用于所有

session mysql> set global time_zone='+8:00';

Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone |        |
| time_zone        | +08:00 |
+------------------+--------+
2 rows in set, 1 warning (0.00 sec)