Java之注解和反射学习笔记十五 —— 反射获取泛型

Java之注解和反射学习笔记十五 —— 反射获取泛型

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参考教程B站狂神https://www.bilibili.com/video/BV1p4411P7V3

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package pers.ylw.reflection;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;

//通过反射获取泛型
public class Test11 {
    public void test01(Map<String,User> map, List<User> list){
        System.out.println("test01");
    }

    public Map<String,User> test02(){
        System.out.println("test02");
        return null;
    }

    public static void main(String[] args) throws NoSuchMethodException {
        Method method = Test11.class.getMethod("test01", Map.class, List.class);

        Type[] genericParameterTypes = method.getGenericParameterTypes();
        for (Type genericParameterType : genericParameterTypes) {
            System.out.println("getGenericParameterTypes-->" + genericParameterType);
            //如果泛型的参数类型属于参数化类型(判断Map和List内部的参数类型)
            if (genericParameterType instanceof ParameterizedType){
                //强转后或获得真实的参数类型
                Type[] actualTypeArguments = ((ParameterizedType) genericParameterType).getActualTypeArguments();
                for (Type actualTypeArgument : actualTypeArguments) {
                    System.out.println(actualTypeArgument);
                }
            }
        }

        System.out.println("============================================");
        method = Test11.class.getMethod("test02",null);
        Type genericReturnType = method.getGenericReturnType();
        if (genericReturnType instanceof ParameterizedType){
            //强转后或获得真实的参数类型
            Type[] actualTypeArguments = ((ParameterizedType) genericReturnType).getActualTypeArguments();
            for (Type actualTypeArgument : actualTypeArguments) {
                System.out.println(actualTypeArgument);
            }
        }

    }
}