For details, the technical principles and applications of Validation :: API framework in the Java library S)
Validation API is a framework commonly used in the Java class library for data verification and verification in the application.It provides a simple and flexible way to ensure the legality and integrity of the data, thereby improving the quality and reliability of the application.
Technical principle:
The technical principle of Validation API is based on the annotations and reflection mechanisms in Java.Users can describe the verification rules of the data through adding related annotations to the classes, such as@notnull,@min,@max, etc.When using the Validation API for a data verification, it obtains the attribute annotation information through the reflex mechanism and verify the data according to the rules defined by the annotation.
Application scenario:
Validation API has a wide range of application scenarios in applications.Here are some common ways of use.
1. Form verification:
In web applications, when users submit form data, the data often needs to be verified.Validation API can be used to verify the legitimacy of form data to ensure that the data entered by the user meets the requirements.For example, you can use the @EMAIL annotation to verify the format of the email address,@SIZE annotation to verify the length of the input character.
public class User {
@NotEmpty
private String username;
@Email
private String email;
@Size(min = 6, max = 12)
private String password;
// omit the getter and setter method
}
2. Parameter verification:
When the method calls, the Validation API can be used to verify the parameters of the method to ensure the requirements of the parameter satisfaction method.For example, you can use the @Notnull annotation to verify the parameter cannot be empty,@min notes the minimum value of the verification parameter.
public void updateUser(@NotNull Long id, @NotEmpty String name, @Min(18) int age) {
// method body
}
3. Database verification:
Before accessing the database, you can use the Validation API to verify the data to be inserted or updated.This can prevent illegal data from entering the database and ensure the integrity and consistency of the data.
public void addUser(User user) {
// Data validation
ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
Validator validator = validatorFactory.getValidator();
Set<ConstraintViolation<User>> violations = validator.validate(user);
if (!violations.isEmpty()) {
// Treatment the verification results
} else {
// Execute the database operation
}
}
Summarize:
Validation API is a convenient and powerful data verification framework in the Java library.By using the technical principles based on annotations and reflection mechanisms, it provides a simple and flexible way to verify and verify the data.In practical applications, we can widely apply Validation API to ensure the legitimacy of data and improve the quality and reliability of applications.
