Jakarta Bean Validation API's application and principles in the Java class library
Jakarta Bean Validation (referred to as BV) is an API used to realize data verification in the Java library.It provides a simple and powerful way to verify the attributes of the JavaBean object to ensure the integrity and accuracy of the data.This article will introduce the application and principles of BV in the Java library, and provide relevant Java code examples.
1. Application scenario
In modern software development, data verification is crucial.By using BV, developers can verify the input data by writing simple annotations and rules in a unified and scalable way.BV can be applied to various scenarios, such as:
-Ke use the form data of the user input is legal;
-Che verify whether the attributes in the configuration file meet the requirements;
-Kex the effectiveness of its attributes before the object's persistence;
-Che verification whether the request parameters are legal in the web application.
2. Principles
BV is implemented based on Java's annotations and reflex mechanisms.Developers need to add corresponding annotations to JavaBean, which need to be verified and define verification rules.When the application calls BV for verification, BV will obtain the attributes and annotation information of JavaBean through reflex, and then verify the rules defined by the annotation.
The core principle of BV can be summarized as the following steps:
-Wet the target of the target JavaBean;
-Ad the attributes and corresponding annotations of JavaBean with the reflex mechanism;
-The traverser attribute annotation list, verify according to the rules defined by the annotation;
-If the verification fails, record error information;
-Awat the verification results.
3. Example code
The following is an example code that uses BV for data verification:
First, we define a User class as the JavaBean object:
public class User {
@NotNull
private String username;
@Size(min = 6, max = 20)
private String password;
// omit other attributes and methods
}
Then, we use the BV to verify the User class:
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername(null);
user.setPassword("123");
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 example code, we first created a User object and set up invalid Username and Password.Then, we obtained verification objects through ValidatorFactory and Validator and verified the User object.Finally, we iterate through the verification results and output error messages.
Through the above example code, we can see that using BV for data verification is very easy.Developers only need to add corresponding annotations to the attributes that need to be verified, and then verify it with Validator.
Summarize:
This article introduces the application and principles of Jakarta Bean Validation API in the Java library.Using BV can easily implement data verification and improve the integrity and accuracy of data.Through simple annotations and rules, developers can easily verify the JavaBean object.
