如何查看JDBC规范版本？
在mysql-connector-j-8.0.33.jar的META-INF下，打开MANIFEST.MF文件，就能看到如下内容：
Manifest-Version: 1.0
Ant-Version: Apache Ant 1.10.7
Created-By: 1.8.0_241-b07 (Oracle Corporation)
Built-By: pb2user
Specification-Title: JDBC
Specification-Version: 4.2
Specification-Vendor: Oracle Corporation
Implementation-Title: MySQL Connector/J
Implementation-Version: 8.0.33
Implementation-Vendor-Id: com.mysql
文件内容中 Specification-Version: 4.2 这一项，就代表实现的JDBC规范的版本号，是4.2。
D:\MavenArtifactRepo\com\mysql\mysql-connector-j\8.0.33\mysql-connector-j-8.0.33.jar!\META-INF\MANIFEST.MF