(Notes written by Java beginners)
There are times when you want to see what version of the JDK the Java war file was built with. In such a case, you can check with the following command. First, unzip the war file.
If the war file is unzipped in the document root of Tomcat, refer to the class file in it. For a locally existing war file, change the extension to zip and unzip the zip file.
example.war -> example.zip
After decompressing, use the cd command to move to the directory where the class file exists.
javap -v [Class file name]
In the execution result
major version: 52
If the output is, subtract 44 from that value.
52 - 44 = 8
So you can see that it was built with JDK version 8.