Learn the key points of the technical principle of "AutoValue Processor" framework in the Java library

AutoValue is a library that simplifies Java's unable variable objects. It can automatically generate methods such as Setter, Getter, and Equals, which greatly simplifies the code writing process.AutoValue Processor is a special annotation processor of the AutoValue library that can help automatically generate the class required by AutoValue during compilation. The key points of the key points of AutoValue Processor are as follows: 1. Annotation processor: AutoValue Processor is an annotation processor that scans a specific annotation class in the compilation source code and generates a new Java class based on the content of the annotation.It uses Java annotations to process API to implement this function. 2. AbstractProcessor class: AutoValue Processor inherited the AbstractProcessor class, which is one of the core categories in the Java annotation API.AutoValue Processor needs to rewrite the Process method, which defines the main logic of the annotation processor. Below is a simple example code of AutoValue Processor: import com.google.auto.service.AutoService; import com.google.auto.value.AutoValue; import javax.annotation.processing.AbstractProcessor; import javax.annotation.processing.Processor; import javax.annotation.processing.RoundEnvironment; import javax.lang.model.SourceVersion; import javax.lang.model.element.Element; import javax.lang.model.element.TypeElement; import java.util.Set; @AutoService(Processor.class) public class AutoValueProcessor extends AbstractProcessor { @Override public Set<String> getSupportedAnnotationTypes() { return Set.of(AutoValue.class.getCanonicalName()); } @Override public SourceVersion getSupportedSourceVersion() { return SourceVersion.latestSupported(); } @Override public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) { for (Element element : roundEnv.getElementsAnnotatedWith(AutoValue.class)) { // Here // ... } return true; } } In the above sample code, AutoValueProcessor uses Google's Auto-Service library from the registered annotation processor.The annotation processor supports processing the class that marked the AutoValue annotation and generates a new Java class as needed.The code logic of the specific class can be written according to actual needs. It should be noted that in order to enable the AutoValue Processor, it needs to be packaged as a jar file and add it to the class path when compiling.At the same time, you need to use the -processor option of the Java compiler during compilation to specify the AutoValue Processor. To sum up, AutoValue Processor is an annotation processor of the AutoValue library. It can automatically generate related Java classes according to the content of the annotation.By using AutoValue Processor, we can create unable variable objects more conveniently and reduce manually writing a large number of repetitive code.