The technical principles of verification framework framework in the Java library

The verification framework is a widely used technology in the field of software development, which plays an important role in the Java class library.The verification framework can help programmers verify the legitimacy of input data and provide a simple and convenient method to handle errors.In this article, we 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. Technical principle: The core principle of the verification framework is to verify the effectiveness of the input data by defining and implementing verification rules.The verification framework in the Java library is usually implemented based on annotations and reflection mechanisms.The following is a detailed description of the technical principles of the verification framework in the Java library: 1.1 Note: The verification framework in the Java library uses annotations to mark the fields or methods that need to be verified.By using specific annotations on the corresponding fields or methods, programmers can specify the corresponding verification rules.For example, commonly used annotations include @Notnull (cannot be empty),@min (minimum value),@max (maximum value), etc. 1.2 reflection mechanism: The verification framework uses the Java's reflection mechanism to retrieve the fields or methods marked marked, and verify it according to the verification rules defined by the annotation.Through the reflection mechanism, the verification framework can dynamically obtain the value of the field or method and pass it to the corresponding verification device for verification. 1.3 Validator: The verification device in the verification framework is responsible for performing actual verification logic.The verification device verifies the input data according to the verification rules defined in the annotation, and returns the corresponding error information based on the verification results.The verification device usually provides the implementation of various verification rules, such as verification string length, verification number range, etc. 1.4 Error treatment: During the verification process, if the input data does not meet the verification rules, the verification framework will generate corresponding error information.Programmers can define custom logic logic, such as displaying error information to users, writing logs, etc. 2. Java code example: Below is a simple Java code example, demonstrating how to use Hibernate Validator (a famous Java verification framework) to verify the effectiveness of a user object: import javax.validation.Validation; import javax.validation.Validator; import javax.validation.constraints.*; public class User { @Notnull (Message = "Username cannot be empty") @Size (min = 5, max = 20, message = "User name length must be between 5 and 20") private String username; @Notnull (Message = "Age cannot be empty") @Min (Value = 18, Message = "Age cannot be less than 18 years") @Max (Value = 60, Message = "Age cannot be greater than 60 years") private Integer age; // omit other fields and methods public static void main(String[] args) { User user = new User(); user.setUsername(null); user.setAge(16); Validator validator = Validation.buildDefaultValidatorFactory().getValidator(); Set<ConstraintViolation<User>> violations = validator.validate(user); for (ConstraintViolation<User> violation : violations) { System.out.println(violation.getMessage()); } } } In the above code, the `user` class uses the annotations under the annotation of` javax.validation.constraints` to define the verification rules.In the `Main` method, we created a` User` object and manually set up an invalid user name and age.Then, we verified the `User` object provided by the Hibernate Validator and print the error information through iteration error results. Summarize: The verification framework is an important technology in the Java library, which can help programmers verify the legitimacy of input data.Through the annotation and reflection mechanism, the verification framework can dynamically obtain and verify the fields or methods of the object, and generate error information based on the verification results.Using verification frameworks can make developers write and maintain high -quality code easier.The Java code examples provided above demonstrate how to use Hibernate Validator to verify the effectiveness of the object.