十五、反射获取泛型信息

狂神说Java：https://www.bilibili.com/video/BV1p4411P7V3

1、代码

/**
 * @Description 反射获取泛型
 * @Author Administrator
 * @Date 2020/12/2 13:23
 */
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 Exception {

        Class c1 = Test11.class;
        /**
         * 1、参数为泛型
         */
        Method method = c1.getDeclaredMethod("test01", Map.class, List.class);
        Type[] parameterTypes = method.getGenericParameterTypes();
        for (Type type : parameterTypes) {
            System.out.println("参数类型#" + type);
            if(type instanceof ParameterizedType){
                Type[] actualTypeArguments = ((ParameterizedType) type).getActualTypeArguments();
                for (Type actualTypeArgument : actualTypeArguments) {
                    System.out.println("\t" + actualTypeArgument);
                }

            }
        }

        /**
         * 2、返回值为泛型
         */
        System.out.println("=======================================");
        method = c1.getDeclaredMethod("test02",null);
        Type returnType = method.getGenericReturnType();
        System.out.println("返回值类型#" + returnType);
        if(returnType instanceof ParameterizedType){
            Type[] actualTypeArguments = ((ParameterizedType) returnType).getActualTypeArguments();
            for (Type actualTypeArgument : actualTypeArguments) {
                System.out.println("\t" + actualTypeArgument);
            }
        }
    }
}

2、结果

参数类型#java.util.Map<java.lang.String, com.hejin.reflection.User>
	class java.lang.String
	class com.hejin.reflection.User
参数类型#java.util.List<com.hejin.reflection.User>
	class com.hejin.reflection.User
=======================================
返回值类型#java.util.Map<java.lang.String, com.hejin.reflection.User>
	class java.lang.String
	class com.hejin.reflection.User

Process finished with exit code 0