Java21新特性
https://docs.oracle.com/en/java/javase/21/core/#Java-Platform%2C-Standard-Edition
升级到Java21指南
https://docs.oracle.com/en/java/javase/21/migrate/index.html#Java-Platform%2C-Standard-Edition
Java8升级到21事项清单
Java21新特性
https://docs.oracle.com/en/java/javase/21/core/#Java-Platform%2C-Standard-Edition
升级到Java21指南
https://docs.oracle.com/en/java/javase/21/migrate/index.html#Java-Platform%2C-Standard-Edition
Java8升级到21事项清单