package com.ljr;

import java.util.*;

public class InterfaceUtils {

    public static List<Class<?>> getInterfaces(Object obj) {
        List<Class<?>> interfaces = new ArrayList<>();
        Class<?> clazz = obj.getClass();
        while (clazz != null) {
            Class<?>[] directInterfaces = clazz.getInterfaces();
            interfaces.addAll(Arrays.asList(directInterfaces));//直接接口
            for (Class<?> directInterface : directInterfaces) {
                interfaces.addAll(getIndirectInterfaces(directInterface));//接口的接口
            }
            clazz = clazz.getSuperclass();//直接父类和间接父类的接口
        }
        return interfaces;
    }

    private static List<Class<?>> getIndirectInterfaces(Class<?> clazz) {
        List<Class<?>> indirectInterfaces = new ArrayList<>();
        Class<?>[] interfaces = clazz.getInterfaces();
        for (Class<?> interfaceClass : interfaces) {
            indirectInterfaces.add(interfaceClass);
            indirectInterfaces.addAll(getIndirectInterfaces(interfaceClass));
        }
        return indirectInterfaces;
    }

    public static void main(String[] args) {
        // 示例用法
        Object obj = new LinkedHashMap<>();
        List<Class<?>> interfaces = getInterfaces(obj);
        for (Class<?> interfaceClass : interfaces) {
            System.out.println(interfaceClass.getName());
        }
    }
}

运行结果：

存在的问题：
该方法可以获取对象的直接接口和间接接口，但是会重复存放。

解决方案：
我们使用了一个HashSet来存储接口，这样可以自动去重。最后，我们将HashSet转换为ArrayList，以便返回一个有序的接口列表。

package com.ljr;

import java.util.*;

public class InterfaceUtils {

    public static List<Class<?>> getInterfaces(Object obj) {
        //List<Class<?>> interfaces = new ArrayList<>();
        Set<Class<?>> interfaces = new HashSet<>();
        Class<?> clazz = obj.getClass();
        while (clazz != null) {
            Class<?>[] directInterfaces = clazz.getInterfaces();
            interfaces.addAll(Arrays.asList(directInterfaces));//直接接口
            for (Class<?> directInterface : directInterfaces) {
                interfaces.addAll(getIndirectInterfaces(directInterface));//接口的接口
            }
            clazz = clazz.getSuperclass();//直接父类和间接父类的接口
        }
        return new ArrayList<>(interfaces);
    }

    private static List<Class<?>> getIndirectInterfaces(Class<?> clazz) {
        List<Class<?>> indirectInterfaces = new ArrayList<>();
        Class<?>[] interfaces = clazz.getInterfaces();
        for (Class<?> interfaceClass : interfaces) {
            indirectInterfaces.add(interfaceClass);
            indirectInterfaces.addAll(getIndirectInterfaces(interfaceClass));
        }
        return indirectInterfaces;
    }

    public static void main(String[] args) {
        // 示例用法
        Object obj = new LinkedHashMap<>();
        List<Class<?>> interfaces = getInterfaces(obj);
        for (Class<?> interfaceClass : interfaces) {
            System.out.println(interfaceClass.getName());
        }
    }
}