C#_数据转换 实用方法

【String转Array】
string str = "123asd456asd789";
单字符：　　string[] a0 = str.Split('a');
多字符：　　string[] a1 = Regex.Split(str, @"asd"); //using System.Text.RegularExpressions;
【Array转String】
int[] i = { 12, 34, 123, 4, 12, 123, 54, 5, 122, 23 };
string str=string.Join("",i);

【JSON转List/Class】using Newtonsoft.Json;
使用　　JsonConvert.DeserializeObject
string jsonStr = "[{"id":1,"name":"liuph1","age":20},{"id":2,"name":"liuph2","age":21}]";
List<className> ls = JsonConvert.DeserializeObject<List<className>>(jsonStr);
【List/Class转JSON】using Newtonsoft.Json;
使用　　JsonConvert.SerializeObject
string jsonStr = JsonConvert.SerializeObject(ls);

【string转byte[]】
byte[] bt = Encoding.UTF8.GetBytes("Hello World!");//string=>byte[]
【byte[]转string】
string str = Encoding.Default.GetString(bt);//byte[]=>string

【URL转码】
string en= HttpUtility.UrlEncode("http://www.baidu.com");
【URL解码】
string de= HttpUtility.UrlDecode(en);

【自定义实体之间的转换】

用explicit来定义. 以下代码 可以实现 test和test1之间的转换。 

test1 t1 = new test1();
test t = new test();
t=(test)t1;
t1=(test1)t;

    public class test
    {
        public int Id;
        public string Name;
        public DateTime Time = DateTime.Now;
        public static explicit operator test(test1 t)
        {
            return new test
            {
                Id = t.Id,
                Name = t.Name + t.Time.ToString("yyyy-MM-dd HH:mm:ss"),
                Time = t.Time
            };
        }
    }
    public class test1
    {
        public int Id;
        public string Name;
        public DateTime Time = DateTime.Now;
        public static explicit operator test1(test t)
        {
            return new test1
            {
                Id = t.Id,
                Name = t.Name + t.Time.ToString("yyyy-MM-dd HH:mm:ss"),
                Time = t.Time
            };
        }
    }

获取时间戳

            System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));
            return (time - startTime).TotalSeconds.ToString("0");

集合ToDictionary时key必须唯一,可以用ToLookUp,相当于Dictionary<key,T>或Dictionary<key,List<T>>

 var lss = ls.ToLookup(x => x.userId);//ls是一个List
 foreach (var item in lss)
 {
     var key = item.Key;
     foreach (var item1 in item)
     {
        var val = item1.userName + item1.password;
     }
}