Spring-boot读书笔记一弄懂ConstraintValidatorPassword, String

In ConstraintValidator<Password, String>, the two generic type parameters are:

First parameter: Password

• This is the annotation type that this validator handles
• It's a custom validation annotation (like @Password) that you would create
• When someone uses @Password on a field, this validator will be called
• Example: @Password private String userPassword;

Second parameter: String

• This is the data type of the value being validated
• It tells the validator what type of object it will receive in the isValid() method
• In this case, it expects a String value (the password)
• The isValid(String password, ...) method parameter matches this type

How it works:

• You create a @Password annotation
• Apply it to a String field: @Password String myPassword
• When validation runs, this validator receives the String value
• The isValid() method validates that String and returns true/false

Other examples:

• ConstraintValidator<Email, String> - validates email strings
• ConstraintValidator<Min, Integer> - validates minimum integer values
• ConstraintValidator<NotNull, Object> - validates any object is not null

The generic types ensure type safety between the annotation and the value being validated.