工作常用的小知识，递归，写日志，序列化，异常处理等

文件操作

文件和文件夹的操作，都来自命名空间System.IO

Directory是一个帮助类库，静态类。用于检查文件是否存在，创建和删除文件夹

DirectoryInfo是文件夹对象

写日志函数 ：public static void Log(string strmsg)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _009__数据库
{
    class OperatorDictionary
    {
        public static string LogPath = AppDomain.CurrentDomain.BaseDirectory + "Log";
        public static void OperatorDir()
        {
            string LogPath = AppDomain.CurrentDomain.BaseDirectory + "LogPath";
            string strPatch = AppDomain.CurrentDomain.BaseDirectory + "\\Log";
            string strPatchLogMove = AppDomain.CurrentDomain.BaseDirectory + "LogMove";
            //Directory是一个帮助类库，静态类。用于检查文件是否存在，创建和删除文件夹
            //DirectoryInfo是文件夹对象
            if (!Directory.Exists(strPatch))
            {
                DirectoryInfo dir = Directory.CreateDirectory(strPatch);
                Directory.Move(strPatch, strPatchLogMove);//移动
                Directory.Delete(strPatchLogMove);//删除
            }
            //文件操作
            string fileName = Path.Combine(LogPath, "log.txt");
            string fileNameCopy = Path.Combine(LogPath, "logCopy.txt");
            string fileNameMove = Path.Combine(LogPath, "logMove.txt");
            if (!File.Exists(fileName))
            {
                Directory.CreateDirectory(LogPath);//打开文件流 （创建文件并写入）注意：重新覆盖的
                //创建文件,
                using (FileStream fs = File.Create(fileName))
                {
                    StreamWriter sw = new StreamWriter(fs);
                    sw.WriteLine("这函数覆盖");
                    sw.Flush();
                }
                using (StreamWriter sw = File.AppendText(fileName))//流写入器（创建/打开文件并写入）
                {
                    string msg = "这个函数是追加到文本中，不覆盖";
                    sw.WriteLine(msg);
                    sw.Flush();
                }
                //读取文件，以下三种方式读取，都是把文件直接读取到内存中
                foreach (var item in File.ReadLines(fileName))
                {
                    Console.WriteLine(item);
                }
                string strResult = File.ReadAllText(fileName);

                Byte[] bt = File.ReadAllBytes(fileName);
                string strValue = Encoding.UTF8.GetString(bt);

                //大文件读写
                using (FileStream stream = File.OpenRead(fileName))//分批读取
                {
                    int length = 5;
                    int result = 0;

                    do
                    {
                        byte[] bytes = new byte[length];
                        result = stream.Read(bytes, 0, 5);
                        for (int i = 0; i < result; i++)
                        {
                            Console.WriteLine(bytes[i].ToString());
                        }
                    }
                    while (length == result);
                }

                File.Copy(fileName, fileNameCopy);
                File.Move(fileName, fileNameMove);
                File.Delete(fileNameCopy);
                File.Delete(fileNameMove);//尽量不要delete
            }
        }
        /// <summary>
        /// 写日志函数
        /// </summary>
        /// <param name="strmsg"></param>
        public static void Log(string strmsg)
        {
            StreamWriter sw = null;
            try
            {
                string strFileName = $"{DateTime.Now.ToString("yyyyMMdd")}.txt";
                string totalPatch = Path.Combine(LogPath, strFileName);
                if (!Directory.Exists(LogPath))
                {
                    Directory.CreateDirectory(LogPath);
                }
                sw = File.AppendText(totalPatch);
                sw.WriteLine($"{DateTime.Now}:{strmsg}");
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (sw != null)
                {
                    sw.Flush();
                    sw.Close();
                    sw.Dispose();
                }
            }
        }
    }
}

 

递归小知识

应用场景，处理树形结构

优点：不需要知道有多少层要递归

缺点：内存爆掉

 

序列化

 有几种序列化：

二进制

XML

Json：用的越来越多

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web.Script.Serialization;//System.Web.Extensions
using Newtonsoft.Json;//nuget Newtonsoft

namespace IOSerialize.Serialize
{
    public class JsonHelper
    {
        #region Json
        /// <summary>
        /// .net框架提供
        /// JavaScriptSerializer
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="obj"></param>
        /// <returns></returns>
        public static string ObjectToString<T>(T obj)
        {
            JavaScriptSerializer jss = new JavaScriptSerializer();
            return jss.Serialize(obj);
        }

        /// <summary>
        /// .net框架提供
        /// JavaScriptSerializer
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="content"></param>
        /// <returns></returns>
        public static T StringToObject<T>(string content)
        {
            JavaScriptSerializer jss = new JavaScriptSerializer();
            return jss.Deserialize<T>(content);
        }

        /// <summary>
        /// 用的比较多，比微软提供的性能高，这个是第三方的类库
        /// 注意：要注意版本，版本不同可能会导致不同，版本要用最新的
        /// JsonConvert.SerializeObject
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="obj"></param>
        /// <returns></returns>
        public static string ToJson<T>(T obj)
        {
            return JsonConvert.SerializeObject(obj);
        }

        /// <summary>
        /// 用的比较多，比微软提供的性能高，这个是第三方的类库
        /// 注意：，版本要用最新的
        /// JsonConvert.DeserializeObject
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="content"></param>
        /// <returns></returns>
        public static T ToObject<T>(string content)
        {
            return JsonConvert.DeserializeObject<T>(content);
        }
        #endregion Json
    }
}