Explore the technical principles of the verification framework framework in the Java library

In the Java library, the verification framework is a common tool to verify the legality and integrity of the input data.The verification framework can help developers avoid common errors and loopholes when writing code, and improve the robustness and reliability of the code.This article will explore the technical principles of the verification framework in the Java class library and provide some Java code examples to help readers better understand. 1. Standard annotation The verification framework usually uses standard annotations to provide metadata for verification rules.Java provides some commonly used standard annotations, such as@notnull,@notblank,@siZe, etc.These annotations can be used for the return value of the parameters, fields or methods of the marking method, and define the corresponding verification rules. The following is an example code using @Notnull annotation: public void validateUser(@NotNull String username, @NotNull String password) { // Verify whether the user name and password are empty // If it is empty, throw an abnormal or perform the corresponding error handling logic } 2. Customized annotation In addition to using standard annotations, developers can also customize annotations to define specific verification rules.By customized annotations, we can define different verification rules for different input parameters. Here are a sample code that uses custom annotations: @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) public @interface Email { String message() default "Invalid email address"; String regex() default "[a-zA-Z0-9]+@[a-zA-Z0-9]+\\.[a-zA-Z0-9]+"; } In the above code, we define an annotation called @email. The annotation can be used to mark the field and specify the default verification rules. 3. Verification device The verification device is one of the core components of the verification framework and is used to perform the actual verification process.The verification device usually verifies the input data based on metadata (annotations) and verification rules, and returns the corresponding information based on the verification results. The following is an example code that uses the verification device: public class UserValidator { public static List<String> validateUser(User user) { List<String> errors = new ArrayList<>(); // Use standard annotations to verify ValidatorFactory factory = Validation.buildDefaultValidatorFactory(); Validator validator = factory.getValidator(); Set<ConstraintViolation<User>> violationSet = validator.validate(user); for (ConstraintViolation<User> violation : violationSet) { errors.add(violation.getMessage()); } // Use custom annotations to verify EmailValidator emailValidator = new EmailValidator(); if (!emailValidator.isValid(user.getEmail())) { errors.add("Invalid email address"); } return errors; } } In the above code, we verify the input user objects using the verification device in the Java library.First of all, we used standard annotations to provide basic verification, and then used custom annotations for additional custom verification. Summary: The verification framework in the Java class library realizes flexible verification of the input data through the combination of annotations and the verification device.Through standard annotations and custom annotations, developers can easily define and apply various verification rules.At the same time, the verification framework also provides a wealth of API, so that we can perform corresponding error treatment or logical control according to the verification results.Through reasonable use of the verification framework, we can improve the reliability and security of the code and reduce errors and loopholes in the development process.