Spring Boot Custom Validator annotations

Spring boot can use @valid to verify when the post accepts an object parameter, as in the following code

When you create a user class

The above @notblank and @past made a judgment on how to do similar annotations to validate the data

To create an Myconstraint interface

@Retention: Used to describe the life cycle of the annotation class. It has the following three parameters:
Retentionpolicy.source: Annotations remain in the source file only
Retentionpolicy.class: Annotations remain in the CLASS file and discarded when loaded into the JVM virtual machine
Retentionpolicy.runtime: Annotations remain during a program run, at which point all annotations defined on a class can be obtained through reflection.

@Target: Used to indicate that the annotation can be declared before those elements.
Elementtype.type: Note that the note can only be declared before a class.
Elementtype.field: Note that the note can only be declared in front of a field in a class.
Elementtype.method: Indicates that the annotation can only be declared before a method of a class.
Elementtype.parameter: Note that the note can only be declared before a method parameter.
Elementtype.constructor: Note that the annotation can only be declared before the constructor of a class.
Elementtype.local_variable: Note that the note can only be declared before a local variable.
Elementtype.annotation_type: Note that the note can only be declared before an annotation type.
Elementtype.package: Note that the note can only be declared before a package name.

@Constraint to limit the way custom annotations are defined
The class that is written here is the following custom class

The methods inside the interface are those on other annotations, such as @past

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Spring Boot Custom Validator annotations