import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class UserInfo {
    private String userId;

    private String userName;
}

@Target({ElementType.TYPE}) //加在類(lèi)上的注解
@Retention(RetentionPolicy.SOURCE) //作用于編譯期
public @interface Getter {
}
@Target({ElementType.TYPE}) //加在類(lèi)上的注解
@Retention(RetentionPolicy.SOURCE) //作用于編譯期
public @interface Setter {
}

public abstract class MyAbstractProcessor extends AbstractProcessor {
    //語(yǔ)法樹(shù)
    protected JavacTrees trees;

    //構(gòu)建語(yǔ)法樹(shù)節(jié)點(diǎn)
    protected TreeMaker treeMaker;

    //創(chuàng)建標(biāo)識(shí)符的對(duì)象
    protected Names names;

    @Override
    public synchronized void init(ProcessingEnvironment processingEnv) {
        super.init(processingEnv);
        this.trees = JavacTrees.instance(processingEnv);
        Context context = ((JavacProcessingEnvironment) processingEnv).getContext();
        this.treeMaker = TreeMaker.instance(context);
        this.names = Names.instance(context);
    }

    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
        //獲取注解標(biāo)識(shí)的類(lèi)
        Set<? extends Element> set = roundEnv.getElementsAnnotatedWith(getAnnotation());
        //拿到語(yǔ)法樹(shù)
        set.stream().map(element -> trees.getTree(element)).forEach(jcTree -> jcTree.accept(new TreeTranslator() {
            //拿到類(lèi)定義
            @Override
            public void visitClassDef(JCTree.JCClassDecl jcClassDecl) {
                List<JCTree.JCVariableDecl> jcVariableDeclList = List.nil();
                //拿到所有成員變量
                for (JCTree tree : jcClassDecl.defs) {
                    if (tree.getKind().equals(Tree.Kind.VARIABLE)) {
                        JCTree.JCVariableDecl jcVariableDecl = (JCTree.JCVariableDecl) tree;
                        jcVariableDeclList = jcVariableDeclList.append(jcVariableDecl);
                    }
                }

                jcVariableDeclList.forEach(jcVariableDecl -> {
                    jcClassDecl.defs = jcClassDecl.defs.prepend(makeMethodDecl(jcVariableDecl));
                });
                super.visitClassDef(jcClassDecl);
            }
        }));
        return true;
    }

    /**
     * 創(chuàng)建方法
     * @param jcVariableDecl
     * @return
     */
    public abstract JCTree.JCMethodDecl makeMethodDecl(JCTree.JCVariableDecl jcVariableDecl);

    /**
     * 獲取何種注解
     * @return
     */
    public abstract Class<? extends Annotation> getAnnotation();
}

@SupportedAnnotationTypes("com.ingxx.processor.Setter") //注解處理器作用于哪個(gè)注解 也可以重寫(xiě)getSupportedAnnotationTypes
@SupportedSourceVersion(SourceVersion.RELEASE_8) //可以處理什么版本 也可以重寫(xiě)getSupportedSourceVersion
public class SetterProcessor extends MyAbstractProcessor {

    @Override
    public JCTree.JCMethodDecl makeMethodDecl(JCTree.JCVariableDecl jcVariableDecl) {
        ListBuffer<JCTree.JCStatement> statements = new ListBuffer<>();
        //生成函數(shù)體 this.name = name;
        statements.append(treeMaker.Exec(treeMaker.Assign(treeMaker.Select(treeMaker.Ident(names.fromString("this")), jcVariableDecl.getName()),treeMaker.Ident(jcVariableDecl.getName()))));
        JCTree.JCBlock body = treeMaker.Block(0, statements.toList());
        //生成方法
        return treeMaker.MethodDef(
                treeMaker.Modifiers(Flags.PUBLIC), //訪問(wèn)標(biāo)志
                getNewMethodName(jcVariableDecl.getName()), //名字
                treeMaker.TypeIdent(TypeTag.VOID), //返回類(lèi)型
                List.nil(), //泛型形參列表
                List.of(getParameters(jcVariableDecl)), //參數(shù)列表
                List.nil(), //異常列表
                body, //方法體
                null //默認(rèn)方法（可能是interface中的那個(gè)default）
        );
    }

    @Override
    public Class<? extends Annotation> getAnnotation() {
        return Setter.class;
    }

    private Name getNewMethodName(Name name) {
        String fieldName = name.toString();
        return names.fromString("set" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1, name.length()));
    }

    private JCTree.JCVariableDecl getParameters(JCTree.JCVariableDecl prototypeJCVariable) {
        return treeMaker.VarDef(
                treeMaker.Modifiers(Flags.PARAMETER), //訪問(wèn)標(biāo)志
                prototypeJCVariable.name, //名字
                prototypeJCVariable.vartype, //類(lèi)型
                null //初始化語(yǔ)句
        );
    }
}

@SupportedAnnotationTypes("com.ingxx.processor.Getter") //注解處理器作用于哪個(gè)注解 也可以重寫(xiě)getSupportedAnnotationTypes
@SupportedSourceVersion(SourceVersion.RELEASE_8) //可以處理什么版本 也可以重寫(xiě)getSupportedSourceVersion
public class GetterProcessor extends MyAbstractProcessor {

    @Override
    public JCTree.JCMethodDecl makeMethodDecl(JCTree.JCVariableDecl jcVariableDecl) {
        ListBuffer<JCTree.JCStatement> statements = new ListBuffer<>();
        //生成函數(shù)體 return this.字段名
        statements.append(treeMaker.Return(treeMaker.Select(treeMaker.Ident(names.fromString("this")), jcVariableDecl.getName())));
        JCTree.JCBlock body = treeMaker.Block(0, statements.toList());
        //生成方法
        return treeMaker.MethodDef(treeMaker.Modifiers(Flags.PUBLIC), getNewMethodName(jcVariableDecl.getName()), jcVariableDecl.vartype, List.nil(), List.nil(), List.nil(), body, null);
    }

    @Override
    public Class<? extends Annotation> getAnnotation() {
        return Getter.class;
    }

    private Name getNewMethodName(Name name) {
        String fieldName = name.toString();
        return names.fromString("get" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1, name.length()));
    }
}

javac -cp $JAVA_HOME/lib/tools.jar *.java -d . 

@Getter
@Setter
public class UserInfo {
    private String userId;

    private String userName;

    public static void main(String[] args) {
        UserInfo userInfo = new UserInfo();
        userInfo.setUserId("001");
        userInfo.setUserName("得物");
        System.out.println("id = "+userInfo.getUserId()+" name = "+userInfo.getUserName());
    }
}

//多個(gè)處理器用逗號(hào)分隔
javac -processor com.ingxx.processor.GetterProcessor,com.ingxx.processor.SetterProcessor UserInfo.java -d .