org.chobit.apt.ToJsonStringProcessor Maven / Gradle / Ivy

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package org.chobit.apt;


import com.sun.tools.javac.code.Flags;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.util.List;
import com.sun.tools.javac.util.Name;

import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.ElementFilter;
import java.util.HashSet;
import java.util.Set;


/**
 * {@code @ToJsonString}注解处理
 *
 * @author robin
 */
public class ToJsonStringProcessor extends AbstractTypeProcessor {


    @Override
    public Set getSupportedAnnotationTypes() {
        Set annoTypes = new HashSet<>(1);
        annoTypes.add(ToJsonString.class.getCanonicalName());
        return annoTypes;
    }


    @Override
    public boolean process(Set annotations, RoundEnvironment roundEnv) {

        if (!isInitialized()) {
            return true;
        }

        Set typeElements = ElementFilter.typesIn(roundEnv.getElementsAnnotatedWith(ToJsonString.class));
        if (typeElements.isEmpty()) {
            return true;
        }

        for (TypeElement ele : typeElements) {
            this.makeToStringMethod(ele);
        }

        return true;
    }


    private void makeToStringMethod(TypeElement typeElement) {
        makeImport(typeElement, JsonStringSerializer.class);

        JCTree.JCModifiers modifiers = getTreeMaker().Modifiers(Flags.PUBLIC, List.nil());
        JCTree.JCExpression returnType = getClassExpression(String.class.getName());

        List parameters = List.nil();
        List generics = List.nil();
        Name methodName = getName("toString");
        List exceptThrows = List.nil();

        JCTree.JCBlock methodBody = makeToStringBody();

        JCTree.JCMethodDecl methodDecl =
                getTreeMaker().MethodDef(modifiers, methodName, returnType, generics, parameters, exceptThrows,
                        methodBody, null);

        JCTree.JCClassDecl classDecl = (JCTree.JCClassDecl) getTrees().getTree(typeElement);

        classDecl.defs.append(methodDecl);
    }


    private JCTree.JCBlock makeToStringBody() {
        JCTree.JCExpression serializerIdent = getMethodExpression(JsonStringSerializer.class.getName(), "toJson");
        List toJsonArgs = List.from(List.of(getTreeMaker().Ident(getName("this"))));


        JCTree.JCReturn returnStatement = getTreeMaker().Return(
                getTreeMaker().Apply(List.nil(), serializerIdent, toJsonArgs)
        );

        return getTreeMaker().Block(0, List.of(returnStatement));
    }


}