How to implement the verification framework in the Java library
Implementing a verification framework is a common demand in the Java library. It can be used to verify the user input and ensure the correctness of business logic.This article will introduce how to use the Java library to implement a basic verification framework and provide corresponding code examples.
## introduce
The verification framework is a tool for ensuring the effectiveness and correctness of the data that is introduced.By introducing a verification framework, we can reduce the redundant verification logic in the code and improve the readability and maintenance of the code.This article will introduce how to achieve a simple verification framework.
## Step
The following is the step required to implement the verification framework:
### 1. Create annotations
First, we need to create some annotations to identify the verification rules.For example, we can create a `@notnull annotation, indicating that the field cannot be empty.We can also create annotations of `@minlength` and`@maxlength`, indicating the minimum and maximum length of the field.According to the needs, you can create more annotations.The following is a sample code for creating the annotation of `@notnull`:
import java.lang.annotation.*;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface NotNull {
String message() default "Field cannot be null";
}
### 2. Create the verification device interface
Next, we need to create a verification device interface to define the basic behavior of the verification device.The interface should contain a verification method, receiving an object as a parameter, and returning a `Boolean` value to indicate whether the verification is passed.The following is the example code of the verification device interface:
public interface Validator {
boolean validate(Object obj);
}
### 3. Create a verification device implementation class
We can then create some verification device implementation classes for specific verification logic.For example, we can create a `notnullValidator` class to verify whether the field is` null`.The following is an example code of the `notnullValidator` class:
public class NotNullValidator implements Validator {
@Override
public boolean validate(Object obj) {
return obj != null;
}
}
### 4. Create a verification engine
Next, we need to create a verification engine to drive the entire verification process.The engine should receive a list of objects and related verifications and verify the objects in turn.The following is an example code of the verification engine:
import java.lang.reflect.Field;
import java.util.List;
public class ValidationEngine {
public void validate(Object obj, List<Validator> validators) throws ValidationException {
for (Validator validator : validators) {
if (!validator.validate(obj)) {
throw new ValidationException("Validation failed");
}
}
}
}
### 5. Use the verification framework
Now, we can use the verification framework to verify the object.First, we need to add corresponding verification annotations to the field of the target class.We can then use the verification engine instance and pass the verification list to use the verification framework.The following is an example code that uses the verification framework:
public class User {
@NotNull
private String username;
@MinLength(5)
@MaxLength(10)
private String password;
// omit other fields and methods
}
public class Main {
public static void main(String[] args) {
User user = new User();
user.setUsername("John");
user.setPassword("password");
ValidationEngine engine = new ValidationEngine();
try {
engine.validate(user, Arrays.asList(
new NotNullValidator(),
new MinLengthValidator(),
new MaxLengthValidator()
// Add other verification device
));
System.out.println("Validation passed");
} catch (ValidationException e) {
System.out.println("Validation failed: " + e.getMessage());
}
}
}
In the above code example, the corresponding verification annotation is used on the field of the `User` class. The` main` class creates the verification engine and passes the verification list list to verify the `user` object.If the verification fails, it will be thrown out of the exception.
## in conclusion
By achieving the above steps, we can easily implement a verification framework in the Java library.This framework can help us ensure the effectiveness and accuracy of the data in the data and reduce the verification logic in the code.According to the needs, we can customize multiple verifications and annotations to achieve more complicated verification rules.
