How to customize the verification rules of the Java Ee Validation framework
Custom Java EE verification framework verification rules
The Java Ee Validation framework allows developers to define and execute verification rules by annotations and constraints.In some cases, developers may need to customize verification rules to meet specific business needs.This article will introduce how to customize the verification rules of the Java Ee Validation framework and provide the corresponding Java code example.
Learn Java Ee Validation framework
First, let's learn about the Java Ee value framework.This framework provides a set of pre -defined verification rules through comments and constraints of Java, such as@notnull,@size,@email, etc.Developers can verify the validity of data by applying these comments to the fields or method parameters of the Java object.
Custom verification rules
Custom verification rules usually need to create a customized verification annotation and corresponding verification device.The following is the basic step of custom verification rules:
1. Create a customized verification annotation: Use @Target and @RETENTION notes to specify the goals and retention strategies of the annotation, as shown below:
import java.lang.annotation.*;
@Target({ ElementType.FIELD, ElementType.PARAMETER })
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = CustomValidator.class)
public @interface CustomValidation {
String message() default "Invalid data";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
In the above code, we created a custom noted called Customvalidation, and used @Constraint to specify the corresponding verification device as CustomValidator.
2. Create a custom verification device: Create a verification device class that implements the ConstraintValidator interface to handle the authentication rules for customized.The following is an example code:
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
public class CustomValidator implements ConstraintValidator<CustomValidation, String> {
@Override
public void initialize(CustomValidation constraintAnnotation) {
// Initialize the verification device
}
@Override
public boolean isValid(String value, ConstraintValidatorContext context) {
// Custom logic of the implementation of verification rules
if (value == null) {
return false;
}
return value.equals("custom");
}
}
In the above example, we created a verification class called CustomValidator and implemented the ISVALID method to define customized verification rules.The ISVALID method returns a Boolean value to indicate whether to verify whether to pass.
Apply customized verification rules
When using custom verification rules, you need to apply customized verification annotations on the fields or method parameters of the Java object.The following is an example code that applies customized verification rules:
public class User {
@CustomValidation
private String username;
// getter and setter method
}
In the above example, we applied customized verification annotations @CustomValidation to the Username field of the User object.
verify the data
Finally, we need to use the Java Ee Validation framework to verify the data.The following is an example code that uses the verification data that uses custom verification rules:
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername("custom");
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
}
}
In the above examples, we use the BUILDDEFAULTVALIDIDACTORY method of the Validation class to obtain a verification factory object and use the object to obtain a verification object.We then call the validate method of the verification device to verify the data of the User object and obtain the set of the verification results.Finally, we use for cycle to traverse the verification results collection and print the message of verification errors.
Summarize
This article introduces how to customize the verification rules of the Java Ee Validation framework.By creating a customized verification annotation and verification device, we can define and apply our own business verification rules.I hope this article will help you understand and use the Java Ee value framework.
The above is a knowledge article about how to customize the verification rules of the Java Ee Validation framework.
