The best practice of the JSR 303 verification constraint framework
The best practice of JSR 303 verification constraint framework
introduction:
JSR 303 is a standard specification for verifying object attributes in Java.It provides a simple and powerful way to define and apply constraints to ensure the integrity and legality of the application data.This article will explore the best practice of the JSR 303 verification constraint framework, and some matters that should be paid attention to when using the framework.
1. Introduce dependencies
First of all, we need to introduce the dependencies of the JSR 303 verification constraint framework in our project.We can add the following dependencies to the construction file of the project:
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>2.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.validator</groupId>
<artifactId>hibernate-validator</artifactId>
<version>6.1.6.Final</version>
</dependency>
2. Create verification constraints
Next, we need to define verification and constraints on our physical class or data objects.We can use annotations to specify constraints.Here are some commonly used constraints:
-@Notnull: The attribute value cannot be empty.
-@Size: The size of the attribute value must be within the specified range.
-@Min: The attribute value must be greater than or equal to the specified minimum value.
-@Max: The attribute value must be less than or equal to the specified maximum value.
-@Email: The attribute value must be a legal email address.
For example, we can define verification constraints on a physical class called User:
public class User {
@NotNull
private String username;
@Size(min = 6, max = 20)
private String password;
@Email
private String email;
// omit other attributes and methods
}
3. Use the verification device to verify
Once we define the verification constraints, we can use the verification device to verify at the place where the data needs to be verified.We can use javax.validation.Validation factory class to create a verification device and pass it to the verified objects to it.The following is an example method for verifying the User object:
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
public class UserValidator {
private Validator validator;
public UserValidator() {
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
validator = factory.getValidator();
}
public Set<ConstraintViolation<User>> validate(User user) {
return validator.validate(user);
}
}
In this example, we used javax.validation.Validation factory classes to create a verification device.We then use the value method to verify the user object.If the verification fails, it will return an SET object that contains violations of constraints.
4. Processing verification results
After verification, we can take appropriate actions based on the verification results.We can check whether the verification results are empty, and if it is not empty, it means that there is a violation of restrictions.We can traverse the SET objects that violate the constraint and processed as needed.The following is an example method for processing verification results:
import javax.validation.ConstraintViolation;
import java.util.Set;
public class UserValidator {
// omit the previous code
public void processValidationResult(Set<ConstraintViolation<User>> violations) {
if (!violations.isEmpty()) {
for (ConstraintViolation<User> violation : violations) {
System.out.println(
"Attribute name:" + violation.getpropertypath (). Tostring () +
", Error message:" + violation.getMessage ()
);
}
}
}
}
In this example, we traversed the SET objects that violate the constraint and print the attribute name and error message.According to actual needs, we can use the appropriate log recorder or error processing mechanism to handle the verification results.
in conclusion:
This article introduces the best practice of the JSR 303 verification constraint framework.By introducing dependencies, defining verification constraints, verification device for verification, and processing verification results, we can easily implement data integrity and legitimacy verification in the application.With these best practices, we can effectively reduce errors and inconsistencies in code, and improve the quality and maintenance of applications.
Appendix: Complete example code
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;
import javax.validation.ConstraintViolation;
import java.util.Set;
public class User {
@NotNull
private String username;
@Size(min = 6, max = 20)
private String password;
@Email
private String email;
// omit other attributes and methods
// getter and setter method
}
public class UserValidator {
private Validator validator;
public UserValidator() {
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
validator = factory.getValidator();
}
public Set<ConstraintViolation<User>> validate(User user) {
return validator.validate(user);
}
public void processValidationResult(Set<ConstraintViolation<User>> violations) {
if (!violations.isEmpty()) {
for (ConstraintViolation<User> violation : violations) {
System.out.println(
"Attribute name:" + violation.getpropertypath (). Tostring () +
", Error message:" + violation.getMessage ()
);
}
}
}
public static void main(String[] args) {
User user = new User();
user.setUsername(null);
user.setPassword("12345");
user.setEmail("invalid_email");
UserValidator validator = new UserValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
validator.processValidationResult(violations);
}
}
I hope this article can help you understand the JSR 303 verification constraint framework and apply it correctly in practice.By following these best practices, you can improve the data quality and consistency of the application and avoid common errors and loopholes.
