c#判断两个对象和对象中的属性是否相同（以及记录对象中的哪些字段，和详细的改变情况）

浅浅的花香味﹌ 2022-03-15 04:26 183阅读 0赞

原文出处：[https://www.cnblogs.com/likui-bookHouse/p/9908045.html][https_www.cnblogs.com_likui-bookHouse_p_9908045.html]

一、当前项目需要记录变更记录，即用户在进行编辑后，将变更操作记录下来。但是数据没有发生变化，则不记录。

代码1：（仅仅返回是否变化的标识）

/// <summary>
        /// 反射对比实体属性变更
        /// </summary>
        /// <typeparam name="T"></typeparam>
        public class CompareEntry<T>
        {
            /// <summary>
            /// 编辑之前的对象和编辑后的对象进行对比
            /// </summary>
            /// <returns></returns>
            public bool CompareDTO(T BeforeDTO, T AfterDTO)
            {
                bool IsEqual = true;
    
                if (BeforeDTO == null || AfterDTO == null)
                {
                    IsEqual = false;
                }
                else if (BeforeDTO.Equals(DBNull.Value) || AfterDTO.Equals(DBNull.Value))
                {
                    IsEqual = false;
                }else if (BeforeDTO.GetType() != AfterDTO.GetType())
                {
                    IsEqual = false;
                    return IsEqual;
                }
                else if (BeforeDTO is int || BeforeDTO is short || BeforeDTO is long || BeforeDTO is float || BeforeDTO is double || BeforeDTO is decimal)
                {
                    //int 01与1      
                    if (BeforeDTO is int)
                    {
                        if (Convert.ToInt32(BeforeDTO) != Convert.ToInt32(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                    else if (BeforeDTO is short)
                    {
                        if (Convert.ToInt16(BeforeDTO) != Convert.ToInt16(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                    else if (BeforeDTO is long)
                    {
                        if (Convert.ToInt64(BeforeDTO) != Convert.ToInt64(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                    else if (BeforeDTO is float)
                    {
                        if (Convert.ToSingle(BeforeDTO) != Convert.ToSingle(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                    else if (BeforeDTO is double)
                    {
                        if (Convert.ToDouble(BeforeDTO) != Convert.ToDouble(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                    else if (BeforeDTO is decimal)
                    {
                        if (Convert.ToDecimal(BeforeDTO) == Convert.ToDecimal(AfterDTO))
                        {
                            IsEqual = false;
                        }
                    }
                }
                else 
                {
                    var beforeMembers = BeforeDTO.GetType().GetProperties();
                    var afterMembers = AfterDTO.GetType().GetProperties();
                    for (int i = 0; i < beforeMembers.Length; i++)
                    {
                        var beforeVal = beforeMembers[i].GetValue(BeforeDTO, null);
                        var afterVal = afterMembers[i].GetValue(AfterDTO, null);
                        var beforeValue = beforeVal == null ? null : beforeVal.ToString();
                        var afterValue = afterVal == null ? null : afterVal.ToString();
                        if (beforeValue != afterValue)
                        {
                            IsEqual = false;
                            break;
                        }
                    }
                }
    
                return IsEqual;       
            }
        }

二、 调整后的代码：（返回标识以及详细变更记录）

/// <summary>
        /// 
        /// </summary>
        public class CompareResult
        {
            /// <summary>
            /// 
            /// </summary>
            public bool IsChange { get; set; }
            /// <summary>
            /// 变跟内容
            /// </summary>
            public string ChangeContent { get; set; }
        }
    
        /// <summary>
        /// 对比实体属性变更(利用反射)
        /// </summary>
        public class CompareEntry
        {
            /// <summary>
            /// 
            /// </summary>
            /// <returns></returns>
            public CompareResult CompareDTO(object BeforeDTO, object AfterDTO)
            {
                CompareResult result = new CompareResult();
                bool b = false;
    
                if (BeforeDTO == null && AfterDTO != null)
                {
                    b = true;
                }
                else if (BeforeDTO != null && AfterDTO == null)
                {
                    b = true;
                }
                else if (BeforeDTO.Equals(DBNull.Value) && !AfterDTO.Equals(DBNull.Value))
                {
                    b = true;
                }
                else if (!BeforeDTO.Equals(DBNull.Value) && AfterDTO.Equals(DBNull.Value))
                {
                    b = true;
                }
                else if (BeforeDTO.GetType() != AfterDTO.GetType())
                {
                    result.IsChange = true;
                    return result;
                }
                else if (BeforeDTO is int || BeforeDTO is short || BeforeDTO is long || BeforeDTO is float || BeforeDTO is double || BeforeDTO is decimal)
                {
                    if (BeforeDTO is int)
                    {
                        if (Convert.ToInt32(BeforeDTO) != Convert.ToInt32(AfterDTO))
                        {
                            b = true;
                        }
                    }
                    else if (BeforeDTO is short)
                    {
                        if (Convert.ToInt16(BeforeDTO) != Convert.ToInt16(AfterDTO))
                        {
                            b = true;
                        }
                    }
                    else if (BeforeDTO is long)
                    {
                        if (Convert.ToInt64(BeforeDTO) != Convert.ToInt64(AfterDTO))
                        {
                            b = true;
                        }
                    }
                    else if (BeforeDTO is float)
                    {
                        if (Convert.ToSingle(BeforeDTO) != Convert.ToSingle(AfterDTO))
                        {
                            b = true;
                        }
                    }
                    else if (BeforeDTO is double)
                    {
                        if (Convert.ToDouble(BeforeDTO) != Convert.ToDouble(AfterDTO))
                        {
                            b = true;
                        }
                    }
                    else if (BeforeDTO is decimal)
                    {
                        if (Convert.ToDecimal(BeforeDTO) == Convert.ToDecimal(AfterDTO))
                        {
                            b = true;
                        }
                    }
                }
                else 
                {
                    StringBuilder content = new StringBuilder();
                    var beforeMembers = BeforeDTO.GetType().GetProperties();
                    var afterMembers = AfterDTO.GetType().GetProperties();
                    for (int i = 0; i < beforeMembers.Length; i++)
                    {
                        var beforeVal = beforeMembers[i].GetValue(BeforeDTO, null);
                        var afterVal = afterMembers[i].GetValue(AfterDTO, null);
                        var beforeValue = beforeVal == null ? null : beforeVal.ToString();
                        var afterValue = afterVal == null ? null : afterVal.ToString();
                        if (beforeValue != afterValue)
                        {
                            b = true;
                            content.Append(beforeMembers[i].Name+"("+ beforeValue+"->"+afterValue+")");
                        }
                    }
                    result.IsChange = b;
                    result.ChangeContent = content.ToString();
                }
    
                return result;       
            }
        }

注意，引用类型进行对比的时候，需要在编辑之前对对象进行拷贝，让拷贝的对象与编辑后的对象进行对比。(因为引用类型不同于值类型，值类型每次操作都会产生一个新的对象，而引用类型在new一个新对象赋值时，其实是在堆上创建了一个内存地址，指向的仍然是原对象，对它操作原对象也会发生变化。所以只有通过拷贝复制一个新对象)

[https_www.cnblogs.com_likui-bookHouse_p_9908045.html]: https://www.cnblogs.com/likui-bookHouse/p/9908045.html