How to customize the JSR 303 verification constraints

How to customize the JSR 303 verification constraint framework Introduction: JSR 303 verification constraint is a framework for performing input verification in Java applications.It provides a variety of annotations and constraints, which can be applied to class attributes to ensure the effectiveness of data.This article will discuss how to customize the JSR 303 verification constraint framework to meet specific verification needs. step: The following is the step of customized JSR 303 verification constraint framework: Step 1: Create custom constraint notes The first step is to create a custom -defined constraint annotation that will be applied to the attributes of the class.To this end, you need to create a Java file containing the following elements: import javax.validation.Constraint; import javax.validation.Payload; import java.lang.annotation.*; @Documented @Constraint(validatedBy = CustomValidator.class) @Target({ElementType.FIELD, ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) public @interface CustomConstraint { String message() default "Invalid field value"; Class<?>[] groups() default {}; Class<? extends Payload>[] payload() default {}; } In the above code, we created a comment called CustomConstraint and mapped it to the CustomValidator class, which will execute verification logic.You can add other elements according to your needs, such as messages, groups and effective loads. Step 2: Realize custom verification logic The second step is to implement the CustomValidator class, which will perform actual verification logic.In this class, you can add your custom verification logic.The following is an example code: import javax.validation.ConstraintValidator; import javax.validation.ConstraintValidatorContext; public class CustomValidator implements ConstraintValidator<CustomConstraint, String> { @Override public void initialize(CustomConstraint constraintAnnotation) { // Initialize logic } @Override public boolean isValid(String value, ConstraintValidatorContext context) { // Add your custom verification logic return value != null && value.matches("[a-zA-Z]+"); } } In the above code, we implement the CustomValidator class, which implement the ConstraintValidator interface and specify the CustomConstraint annotation and attribute types.In the ISVALID method, you can add your custom verification logic.In this example, we check whether the attribute value is a non -empty string. Step 3: Use custom verification annotations After you complete the above two steps, you can use your custom verification annotation on the attributes of the Java class.For example: public class User { @CustomConstraint private String name; // Other attributes and methods } In the above code, we applied the custom notes CustomConstraint on the Name attribute of the User class.When using the JSR 303 verification device to verify the USER object, it will apply the custom verification logic of our definition. End words: By determining the JSR 303 verification constraint framework according to the above steps, you can meet specific verification requirements and ensure the effectiveness of the data.Custom verification logic can be easily applied to a variety of annotations provided by the framework to meet the specific needs of your application.