更新MySQL 8.0需要注意的异常问题

￡神魔★判官ぃ 2022-05-18 07:41 286阅读 0赞

1.启动异常报错：

java.sql.SQLException: Unknown character set index for field '255' received from server.

**原因**： MYSQL 5.5 之前， UTF8 编码只支持1-3个字节;从MYSQL5.5开始，可支持4个字节UTF编码utf8mb4。 **`mysql-connector-java.jar`**的版本问题。mysql的jar包低版本不支持utf8mb4,连接时报错"Unknown character set index for field '255' received from server."升级高一点的**`mysql-connector-java.jar`**版本之后就解决了。

2.启动异常报错：

java.sql.SQLException: The server time zone value 'ÖÐ¹ú±ê×¼Ê±¼ä' 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.

**原因**：时区的错误导致异常，我们只需要设置完毕系统的时区即可。这里的`GMT%2B8`代表东八区。

警告异常：

Tue Jul 31 19:46:30 CST 2018 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.  
**原因**：不建议在没有服务器身份验证的情况下建立SSL连接。根据MySQL 5.5.45 +、5.626+和5.7.6+的要求，如果没有设置显式选项，默认情况下必须建立SSL连接。对于不使用SSL的现有应用程序，verifyServerCertificate属性设置为“false”。您需要通过设置useSSL=false来显式禁用SSL，或者设置useSSL=true，并为提供用于服务器证书验证的信任库。

我们将配置文件中datasource的URL 改为 ：

![70][]

3.启动警告：

**Loading class \`com.mysql.jdbc.Driver'. This is deprecated. The new driver class is \`com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.**

**原因**：加载类'**com.mysql.jdbc.Driver'** 已经过时了。新的驱动类是***“com.mysql.cj.jdbc.Driver”***。驱动程序通过SPI自动注册，而手动加载类通常是不必要的。

我们只需要把 **com.mysql.jdbc.Driver** 改为 **com.mysql.cj.jdbc.Driver** 即可

![70 1][]

[70]: /images/20220518/9eddc979190b44949b7309219248d002.png
[70 1]: /images/20220518/60d0ea55b90d403fab4a2ccf68c2f79b.png