Detailed explanation

Detailed explanation The annotation processor is part of the Java compiler, which can scan and process the annotations in the source code during the compilation period.Annotation processor provides a mechanism that allows developers to generate additional processing code through customized code. The use of the annotation processor is as follows: 1. Definition annotation: Use @Interface keywords to define a annotation in the Java code, which can include attributes and methods in the annotation. // Define a sample notes public @interface MyAnnotation { String value() default ""; int count() default 0; } 2. Create an annotation processor: Write a class to achieve javax.annotion.processing.abstractProcessor class and rewrite the method. public class MyAnnotationProcessor extends AbstractProcessor { @Override public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) { // Treatment the logic of the annotation for (Element element : roundEnv.getElementsAnnotatedWith(MyAnnotation.class)) { // Here you can generate additional processing code // For example, generate a new class according to the attribute value in the annotation MyAnnotation annotation = element.getAnnotation(MyAnnotation.class); String value = annotation.value(); int count = annotation.count(); // ... } return true; } } 3. Configure the annotation processor: In the project's BUILD.GRADLE or Maven's pom.xml file, configure the information about the annotation processor. Example of using Gradle to build tools: groovy dependencies { implementation 'javax.annotation:javax.annotation-api:1.3.2' annotationProcessor 'com.example:my-annotation-processor:1.0' } 4. Use the annotation processor: Use the corresponding annotation and compile the code where you need to use the annotation processor. @MyAnnotation(value = "example", count = 3) public class MyClass { // ... } 5. Run the annotation processor: When compiling items, the annotation processor will be automatically called, scanning and processing the annotations in the code. The annotation processor can scan and process the annotations in the source code during the compilation to generate additional processing code.These processing codes can be used to realize customized functions, such as automatically generating code and realizing specific business logic. Summary: The annotation processor is part of the Java compiler. With the help of the annotation processor, developers can process the code during the compilation to achieve customized functions.Through definition of annotations, creation of annotation processors, configuration annotation processors, and using annotation processors, developers can easily use the annotation processor to generate additional processing code.