业务场景

更新User信息后，需要收集哪些字段的哪些值被更新了。

思路

比较originUser和newUser，收集值不同的属性以及变化前后的值。

代码实现

public static Map<String, Map<String, Object>> getChange(Object originObject, Object newObject) {
        // 存在为null比价就没意义了
        if (ObjectUtils.anyNull(originObject, newObject)) {
            return new HashMap<>();
        }

        // 不同类型无法比较
        if (ObjectUtils.notEqual(originObject.getClass(), newObject.getClass())) {
            return new HashMap<>();
        }

        // 内容都相等所以没必要比较
        if (Objects.deepEquals(originObject, newObject)) {
            return new HashMap<>();
        }

        Map<String, Map<String, Object>> res = Maps.newHashMap();

        Field[] declaredFields = originObject.getClass().getDeclaredFields();
        for (Field field : declaredFields) {
            // 检查Field是否为合成字段、如果该字段是合成字段则不进行比较
            if (field.isSynthetic()) {
                continue;
            }

            // serialVersionUID适用于java序列化机制,非业务属性
            if ("serialVersionUID".equals(field.getName())) {
                continue;
            }

            // 实现方式1
            // field.setAccessible(true);
            // Object o = field.get(originObject);
            // Object n = field.get(originObject);

            // 实现方式2
            PropertyDescriptor propertyDescriptor = null;
            try {
                propertyDescriptor = new PropertyDescriptor(field.getName(), originObject.getClass());
                Method readMethod = propertyDescriptor.getReadMethod();
                Object originValue = readMethod.invoke(originObject);
                Object newValue = readMethod.invoke(newObject);
                if (!Objects.deepEquals(originValue, newValue)) {
                    // 值不相等的话记录属性和值
                    HashMap<String, Object> keyValue = new HashMap();
                    keyValue.put("origin", originValue);
                    keyValue.put("new", newValue);
                    res.put(field.getName(), keyValue);
                }
            } catch (IntrospectionException | IllegalAccessException | InvocationTargetException e) {
                log.error("getChange occur error" + e.getMessage());
            }

        }
        return res;
    }

测试验证

public class MethodUtilsTest {

    @Test
    public void getChangeNoChange() {
        User user1 = new User();
        user1.setName("user2");
        user1.setAge("19");
        user1.setNum("123456");

        User user2 = new User();
        user2.setName("user2");
        user2.setAge("19");
        user2.setNum("123456");

        Map<String, Map<String, Object>> change = MethodUtils.getChange(user1, user2);
        Assert.assertEquals("{}", change.toString());

    }

    @Test
    public void getChangeWithChange() {
        User user1 = new User();
        user1.setName("user1");
        user1.setAge("19");
        user1.setNum("123456");

        User user2 = new User();
        user2.setName("user2");
        user2.setAge("18");
        user2.setNum("123457");

        Map<String, Map<String, Object>> change = MethodUtils.getChange(user1, user2);
        Assert.assertEquals("{num={new=123457, origin=123456}, name={new=user2, origin=user1}, age={new=18, origin=19}}", change.toString());
    }

    @Data
    static class User {
        private String name;
        private String age;
        private String num;
    }
}

参考

对象被更新后、获取更新了的属性和值