The technical principles and applications of verifying the core framework in the Java class library
The technical principles and applications of verifying the core framework in the Java class library
In Java development, the verification core framework is very important. It is used to verify and check data to ensure the legality and integrity of the data.The Java class library provides some verification core frameworks, such as Hibernate Validator and Apache Commons Validator. They use different technical principles to implement data verification.
The technical principles of verifying the core framework mainly include the following aspects:
1. Annotion: The verification framework in the Java class library marks the verification rules by annotating.Developers can add annotations to the field of the physical class to define the verification rules of the field. For example, @notnull means that it cannot be empty,@siZe represents length limit, etc.The framework is analyzed and verified according to the rules.
2. Reflection: Verify the core framework using the reflection mechanism to obtain the field information and annotation information of the physical class.By reflection, the attributes and annotations of the physical class can be dynamically obtained during runtime, and verification can be verified according to the verification rules defined by the annotation.
3. Validator: Verify the core framework to perform data verification through the laboratory.The laboratory is an interface for verifying data, and developers can realize that interface define its own verification rules.The framework is verified by calling the laboratory to determine whether the data meets the verification rules.
The technical application related to this includes the following aspects:
1. Form verification: In Web development, verification core frameworks are often used for form verification.Developers can define the verification rules of the table field by adding annotations to the field of the physical class, such as compulsory items, length limit, data type limit, etc.The framework can be automatically verified according to the annotation, reducing the tedious work of manual verification.
The following is an example code that uses Hibernate Validator to verify form verification:
public class User {
@NotEmpty
private String username;
@Size(min = 6, max = 12)
private String password;
// getter and setter
}
public class FormValidator {
public static void main(String[] args) {
User user = new User();
user.setUsername("");
user.setPassword("123");
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
if (violations.isEmpty()) {
// Form verification passed
System.out.println("Form validation passed.");
} else {
// Output verification error information
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getPropertyPath() + ": " + violation.getMessage());
}
}
}
}
In the above example, the Username field of the User class adds @Notempty annotations, indicating that it cannot be empty. The password field adds @size annotations, indicating that the length is limited to 6 to 12 characters.In the Formvalidator class, a User object is created and verified the object through validator.If the verification passes, the output "form value passed.", Otherwise the output verification error information will be output.
2. Database verification: Verify the core framework can also be used to verify the database data.Developers can define verification rules for database fields by adding annotations to the physical class, such as unique sexual constraints and data type constraints.The framework can automatically verify the database data based on the annotation to ensure the legitimacy of the data.
In summary, the technical principles of the core framework in the Java library mainly include annotations, reflexes and verifications. Their applications cover multiple fields such as form verification and database verification.By using the verification core framework, you can simplify the writing of verification code, improve development efficiency, and ensure the legality and integrity of data.
