BeanUtils和PropertyUtils都是Apache Commons BeanUtils库中的类，用于操作Java对象的属性。它们可以用于读取嵌套的集合属性。

以下是一个示例代码，演示如何使用BeanUtils和PropertyUtils读取嵌套的集合属性：

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.PropertyUtils;
import java.util.List;

public class NestedCollectionExample {

    public static void main(String[] args) {
        Person person = new Person();
        person.setName("John");

        Address address1 = new Address();
        address1.setCity("New York");
        address1.setCountry("USA");

        Address address2 = new Address();
        address2.setCity("London");
        address2.setCountry("UK");

        person.getAddresses().add(address1);
        person.getAddresses().add(address2);

        try {
            // 使用BeanUtils读取嵌套的集合属性
            List
 addresses = (List
) BeanUtils.getProperty(person, "addresses");
            for (Address address : addresses) {
                System.out.println("City: " + address.getCity());
                System.out.println("Country: " + address.getCountry());
            }

            System.out.println();

            // 使用PropertyUtils读取嵌套的集合属性
            addresses = (List
) PropertyUtils.getProperty(person, "addresses");
            for (Address address : addresses) {
                System.out.println("City: " + address.getCity());
                System.out.println("Country: " + address.getCountry());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static class Person {
        private String name;
        private List
 addresses;

        public Person() {
            addresses = new ArrayList<>();
        }

        // 省略getter和setter方法
    }

    public static class Address {
        private String city;
        private String country;

        // 省略getter和setter方法
    }
}

在上面的示例中，我们创建了一个包含嵌套集合属性的Person对象。我们使用BeanUtils和PropertyUtils依次读取嵌套的集合属性"addresses"，并打印每个地址的城市和国家。

请注意，使用BeanUtils或PropertyUtils读取嵌套集合属性时，需要确保嵌套属性的getter方法返回一个集合对象。