"Validation :: API" framework technical analysis in the Java class library (Analysis of Technical Principles of Validation :: API Framework in Java Class Libraries)
"Validation :: API" framework technical principle analysis in the Java class library analysis
Overview:
As the Java application becomes more and more complicated and huge, the importance of data verification has become more and more obvious.By verifying the data entered by the user, we can improve the accuracy and integrity of the data and avoid potential errors to the greatest extent.In order to simplify the process of data verification, the "value :: API" framework in the Java class library came into being.This article will analyze the technical principles of the framework and provide the corresponding Java code example.
Technical principle:
"Validation :: API" framework is a open source framework in the Java class library, which provides a statement method to define and execute data verification rules.The framework is based on the Java Bean Validation API specification. It uses annotations to describe the verification rules and provides a set of validator to perform verification.
The following is the basic principle of data verification using the "value :: API" framework:
1. Define the verification rules:
First, a Java class needs to be created, which represents data objects to be verified.Then, the annotation is used to describe the verification rules of each attribute of the data object.For example, using the @Notnull annotation to require a certain attribute to be not empty. Use @Pattern annotation to request a certain attribute to match a specific regular expression.These annotations are inherited from the Java Bean Validation API, and you can choose the appropriate annotation to describe the verification rules according to specific needs.
The example code is as follows:
public class User {
@NotNull
@Size(min = 1, max = 50)
private String username;
@NotNull
@Email
private String email;
// omit other attributes and methods
}
2. Create a verification device:
Next, you need to create a validator to perform data verification.You can obtain the verification instance through the factory type ValidatorFactory provided by the "Validation :: API" framework.
The example code is as follows:
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
Validator validator = factory.getValidator();
3. Execution verification:
Once there is an verification instance, it can be used to verify the data object.By calling the validate () method of the verification device, you can get a data object to be verified, and you can get a verification result set (set <constraintvilation>).If the attributes in the data object do not meet the verification rules, the value method will return the corresponding verification error information.
The example code is as follows:
User user = new User();
// Set the attribute value of the user object
Set<ConstraintViolation<User>> violations = validator.validate(user);
for (ConstraintViolation<User> violation : violations) {
System.out.println(violation.getMessage());
}
In the above example, if the username attribute is empty or more than 50 characters, or the email attribute is empty or does not meet the email format, the corresponding verification error information will be printed.
Summarize:
Through the "Validation :: API" framework, we can use the annotation to declare verification rules and perform data verification through the verification device.This statement verification method simplifies the process of data verification and provides a scalable method to define customized verification rules.When developing Java applications, using the "Validation :: API" framework can improve the accuracy and integrity of the data and reduce the risk of potential errors.
