The principle of che. :: Commons :: Annotations framework and its advantages in the development of the Java library (Principles of the CHE CORE :: Commons :: Annotations Framework and Its Advantages in Java Class Library DEVELOPMENT)
Chess :: Commons :: Annotations framework and their advantages in the development of Java libraries
Brief introduction
In the development of the Java class library, we often need to use annotations to mark the code and the metadata.Although the Java language itself provides several built -in annotations (such as@Override,@defrecated, etc.), sometimes we need custom annotations to meet specific needs.Che Core :: Commons :: Annotations framework provides a mechanism that simplifies custom annotation development and is convenient for these custom annotations in the class library.
principle
The principle of che. :: Commons :: Annotations framework is very simple. It is implemented based on the Java reflection mechanism.When the Java compiler compiles the source code, check the core :: Commons :: Annotations framework to scan the annotations in the code and process according to the definition of the annotation.By using reflexes, the framework can obtain and handle annotations and their attributes at runtime.
Use Che Core :: Commons :: Annotations
In order to use Chens :: Commons :: Annotations framework, we first need to add related Kuri to the project dependency management.
<dependency>
<groupId>org.eclipse.che.commons</groupId>
<artifactId>che-core-commons-annotations</artifactId>
<version>1.0.0</version>
</dependency>
Then we can define our own annotations:
import org.eclipse.che.commons.annotations.Nullable;
public class MyClass {
@Nullable
private String myField;
@Nullable
public String getMyField() {
return myField;
}
public void setMyField(@Nullable String value) {
myField = value;
}
}
In this example,@Nullable annotations can be null for marking a field or method.
When using cheering :: Commons :: Annotations framework, developers can obtain and handle these custom annotations by reflection.The following is a simple example:
import org.eclipse.che.commons.annotations.Nullable;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
public class Main {
public static void main(String[] args) {
MyClass myObject = new MyClass();
Class<?> clazz = myObject.getClass();
// Get the annotation of the field
Field field = clazz.getDeclaredField("myField");
Nullable nullableAnnotation = field.getAnnotation(Nullable.class);
System.out.println("Nullable annotation present on field: " + (nullableAnnotation != null));
// Comment on the method of obtaining method
Method method = clazz.getDeclaredMethod("getMyField");
nullableAnnotation = method.getAnnotation(Nullable.class);
System.out.println("Nullable annotation present on method: " + (nullableAnnotation != null));
}
}
In this example, we used reflexes to obtain the @Nullable annotation in the MyClass class and the GetmyField method in the MyClass class.By determining whether the annotation exists, we can handle it accordingly according to the definition of the annotation.
Advantage
Che Core :: Commons :: Annotations framework provides a mechanism that simplifies the development of custom annotations. It has the following advantages:
1. Simplified code: Use che. :: Commons :: Annotations framework. You can mark the code by annotation to improve the readability and maintenance of the code.By defining your own annotations, the same functions can be reduced to reduce the use of traditional methods (such as naming specifications).
2. Improve development efficiency: Using annotations can simplify some repetitive operations, reduce the workload of manual processing and writing duplicate code.By automatic scanning and processing, the relevant code generation and metadata analysis can be quickly completed.
3. Increase the scalability of code: By customized annotations, you can add metadata related to business logic to the code to make the code more flexible and scalable.These metadata can be used at runtime, so that the code of code is dynamically adjusted according to actual needs.
Summarize
Che Core :: Commons :: Annotations framework provides a mechanism that simplifies the development of custom annotations, using the Java reflection mechanism to handle and use these annotations.Using this framework can improve the readability and maintenance of code, improve development efficiency, and increase the scalability of code.For the developers of the Java library, Chens :: COMMONS :: Annotations is a tool worth exploring and using.
