在和外部系统对接时，对方系统提供的SDK方法入参全是Map，没办法，只能想办法把对象转成Map。这里，借助了hutool的工具类，可以方便的通过反射获取对象的属性。引入hutool的maven配置：

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.4.1</version>
        </dependency>

工具类代码如下：

import cn.hutool.core.bean.BeanDesc;
import cn.hutool.core.bean.BeanUtil;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

public class BeanConvertUtils {

    public static Map<String, String> beanToMap(Object bean) {
        Map<String, String> targetMap = new HashMap<>();
        if (bean == null) {
            return null;
        }

        //获取类的属性描述
        final Collection<BeanDesc.PropDesc> props = BeanUtil.getBeanDesc(bean.getClass()).getProps();

        String key;
        Method getter;
        Object value;
        for (BeanDesc.PropDesc prop : props) {
            key = prop.getFieldName();
            // 过滤class属性
            // 得到property对应的getter方法
            getter = prop.getGetter();
            if (null != getter) {
                // 只读取有getter方法的属性
                try {
                    value = getter.invoke(bean);
                } catch (Exception ignore) {
                    continue;
                }
                //如果是集合特殊处理
                if (value != null && value instanceof Collection) {
                    listToMap(targetMap, (Collection<Object>) value, key);
                    continue;
                }
                if (value != null && false == value.equals(bean)) {
                    targetMap.put(key, null == value ? null : String.valueOf(value));
                }
            }
        }
        return targetMap;
    }

    private static Map<String, String> listToMap(Map<String, String> targetMap, Collection<Object> collection, String fieldName) {
        int i = 0;
        for (Object bean : collection) {
            Map<String, String> tempMap = beanToMap(bean);
            for (String key : tempMap.keySet()) {
                targetMap.put(fieldName + "[" + i + "]." + key, tempMap.get(key));
            }
            i++;
        }
        return targetMap;
    }
}

写一个测试类，测试一下：

import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

public class BeanConvertUtilsTest {

    @Test
    public void beanToMapTest() {
        Student student = new Student();
        student.setNumber("2023120121");
        student.setName("李磊");
        Course course = new Course();
        course.setName("语文");
        course.setScore("90");
        student.addCourse(course);
        course = new Course();
        course.setName("数学");
        course.setScore("85");
        student.addCourse(course);
        System.out.println(BeanConvertUtils.beanToMap(student));
    }

    private class Student {

        private String number;

        private String name;

        private List<Course> courses;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getNumber() {
            return number;
        }

        public void setNumber(String number) {
            this.number = number;
        }

        public List<Course> getCourses() {
            return courses;
        }

        public void setCourses(List<Course> courses) {
            this.courses = courses;
        }

        public void addCourse(Course course) {
            if (courses == null) {
                courses = new ArrayList<>();
            }
            courses.add(course);
        }
    }

    private class Course {

        private String name;

        private String score;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

        public String getScore() {
            return score;
        }

        public void setScore(String score) {
            this.score = score;
        }
    }
}

跑一下看结果：