The core concept of the Java Ee Validation framework
The core concept of the Java Ee Validation framework
The Java Ee Validation framework is part of the Java Platform Enterprise Edition (Java EE), which aims to provide a standardized way to verify the input data in the application.It is based on the Bean Validation specification and provides a set of annotations and APIs for verifying object attributes.
The following is the core concept of the Java Ee value framework:
1. Constraint Annotations:
The constraint annotation is used to apply the attributes or methods of the verification logic to Java Bean.The Java Ee Validation framework provides multiple built -in constraint annotations, such as@notnull,@siZe,@Pattern, etc.Developers can also create custom constraints to meet specific verification needs.
The following is an example of using constraint annotations:
public class User {
@NotNull
@Size(min = 2, max = 20)
private String name;
// getter and setter
}
2. Validators:
The laboratory is a component that executes verification logic.The Java Ee Validation framework provides a set of built -in inspectionrs to verify various data types, such as string, numbers, and dates.Developers can also create custom verifications by implementing the Validator interface.
The following is an example of using a laboratory:
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
User user = new User();
Set<ConstraintViolation<User>> violations = validator.validate(user);
if (!violations.isEmpty()) {
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
}
In the above example, we verify a User object by calling the value () method.If there are verification errors, we can get error messages by traversing the ConstraintViolation object.
3. Group sequence:
Use a group sequence to specify the verification logic in the specific sequential order.Each set of sequences can contain one or more verification groups.By adding the Groups attribute to the annotation, we can allocate the verification constraints into different groups, so as to flexibly organize verification logic as needed.
The following is an example of using a group sequence:
public interface FirstValidationGroup {}
public interface SecondValidationGroup {}
public class User {
@NotNull(groups = FirstValidationGroup.class)
private String name;
@Size(min = 6, max = 20, groups = SecondValidationGroup.class)
private String password;
// getter and setter
}
Validator validator = Validation.buildDefaultValidatorFactory().getValidator();
User user = new User();
Set<ConstraintViolation<User>> violations = validator.validate(user, FirstValidationGroup.class);
if (!violations.isEmpty()) {
// Process the first group of verification errors
} else {
violations = validator.validate(user, SecondValidationGroup.class);
if (!violations.isEmpty()) {
// Process the second group of verification errors
}
}
In the above example, we allocate the verification constraints into different groups by adding group parameters to the constraint annotation.We can then select the group to be verified as needed to execute the verification logic in the specified order.
The Java EE Validation framework provides a simple and powerful way to verify the input data in the application.By using built -in constraint annotations, verification, and group sequences, developers can easily define and execute verification logic to ensure the legitimacy and accuracy of the data.
