The technical principles of JATBRAINS JAVA Annotations framework in Java Class Library
JetBrains Java Annotations framework is a annotation germ developed by Jetbrains.The library provides a simple and powerful way for Java developers to create and handle annotations.This article will analyze the technical principles of the Javrains Java Annotations framework and provide appropriate Java code examples.
1 Overview
JetBrains Java Annotions framework provides the function of the annotation processor based on the Javax.annotation.Processing package in the java standard library.It uses multiple links in the process of annotation processor and annotations to achieve the generation, verification and modification of the annotation.
2. Comment processor
The annotation processor is a tool for handling the annotation during the compilation period.The JetBrains Java Annotions framework handles the class or method of specific annotations by customized annotations.The annotation processor must implement javax.annotion.processing.abstractProcessor abstraction class and achieves the processing logic of the annotation by covering the process () method.
The following is the code of a sample solution processor:
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.element.Element;
import javax.lang.model.element.TypeElement;
import java.util.Set;
public class MyAnnotationProcessor extends AbstractProcessor {
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
// Treatment of specific annotation logic
for (TypeElement annotation : annotations) {
Set<? extends Element> annotatedElements = roundEnv.getElementsAnnotatedWith(annotation);
for (Element annotatedElement : annotatedElements) {
// Treatment the logic of the annotation
}
}
return true;
}
}
3. Comment processing process
The annotation process of the Jetbrains Java Annotations framework includes multiple links, and each link provides corresponding extension to the logic of the developer's custom annotation processing.
-Aplay: Analyze the annotations in the source code and generate internal representation.This stage is very important because it determines the content of the follow -up process.Developers can specify annotations to be parsed by implementing the interface javax.annotation.processing.processor GetSupportedanNotationTypes () method of GetSupportedanNotationTypes ().
-Keval: Verify the legality and correctness of the annotation.Developers can achieve customized verification logic by implementing the procestess () method of javax.annotion.processing.processor.
-Express: Generate new classes or code fragments according to the annotated information.Developers can generate code by using some tool classes provided by Jetbrains Java Annotations framework, such as com.intellij.codeinsight.annotationUtil.
Below is a sample code segment for using Jetbrains Java Annotations framework to generate a new class:
import com.intellij.codeInsight.AnnotationUtil;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.Tree;
import com.sun.source.util.JavacTask;
import com.sun.source.util.TaskEvent;
import com.sun.source.util.TaskListener;
import com.sun.source.util.TreePath;
import com.sun.source.util.Trees;
import javax.tools.DiagnosticListener;
public class CodeGenerationTaskListener implements TaskListener {
private final Trees trees;
public CodeGenerationTaskListener(JavacTask task) {
this.trees = Trees.instance(task);
}
@Override
public void finished(TaskEvent event) {
if (event.getKind() == TaskEvent.Kind.GENERATE) {
TreePath treePath = event.getCompilationUnit().getTreePath();
ClassTree classTree = (ClassTree) treePath.getLeaf();
String className = getClassName(classTree);
String generatedCode = generateCode(className);
// Insert the generated code into the class file
AnnotationUtil.insertStringAnnotation(classTree, generatedCode);
}
}
private String getClassName(ClassTree classTree) {
// Get the complete name of the class
}
private String generateCode(String className) {
// Generate a new code fragment according to the class name
}
}
4. Use Jetbrains Java Annotations framework
The following steps are required to use Jetbrains Java Annotations framework:
-Atbrains java Annotations framework is added to the project construction file.
-Colon and implement customized annotations processor classes.
-Eregate the customized annotation processing logic in the annotation processor class.
-Wee processor processing the class or method containing the annotation.
Below is an example code that uses Jetbrains Java Annotations framework:
import javax.annotation.processing.Processor;
import javax.tools.JavaCompiler;
import javax.tools.ToolProvider;
public class Main {
public static void main(String[] args) {
// Create a java compiler
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
// Create an annotation processor
Processor processor = new MyAnnotationProcessor();
// Set the annotation processor
compiler.getTask(null, null, null, null, null, null)
.setProcessors(Collections.singleton(processor))
.call();
}
}
This article analyzes the technical principles of Jetbrains Java Annotations framework and provides related Java code examples.By using Javrains Java Annotations framework, developers can easily create and process annotations, thereby improving the flexibility and maintenance of the Java program.
