Linq处理List数据

最近比较喜欢LINQ，真是碉堡了。下面写了个例子演示一下LINQ对List<T>的操作，包括排序、where条件、选部分数据等查询。最近偷懒，不写注释了，大家自己看一下就明白了～

测试用的BLL和Model

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01 public class TestBLL
02 {
03     public List<TestModel> GetList()
04     {
05         return new List<TestModel>()
06         {
07             new TestModel(){ Id=1, Name="RYWE", Content="IOJADJ", Posttime=DateTime.Now.AddHours(1) },
08             new TestModel(){ Id=2, Name="JGFA", Content="CAFYRE", Posttime=DateTime.Now.AddHours(0) },
09             new TestModel(){ Id=4, Name="PIOU", Content="OVXZLA", Posttime=DateTime.Now.AddHours(5) },
10             new TestModel(){ Id=5, Name="OUIH", Content="AIPJLM", Posttime=DateTime.Now.AddHours(3) },
11             new TestModel(){ Id=7, Name="ZCXI", Content="KUQOPA", Posttime=DateTime.Now.AddHours(7) }
12         };
13     }
14 }
15   
16 public class TestModel
17 {
18     public int Id { get; set; }
19     public string Name { get; set; }
20     public string Content { get; set; }
21     public DateTime Posttime { get; set; }
22   
23     public TestModel()
24     {
25     }
26   
27     public override string ToString()
28     {
29         StringBuilder sb = new StringBuilder();
30         sb.Append(String.Format("{0}={1}, ", "Id", this.Id));
31         sb.Append(String.Format("{0}={1}, ", "Name", this.Name));
32         sb.Append(String.Format("{0}={1}, ", "Content", this.Content));
33         sb.Append(String.Format("{0}={1}", "Posttime", this.Posttime));
34         return sb.ToString();
35     }
36 }

测试代码：

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01 static void Main(string[] args)
02 {
03   
04     TestBLL bll = new TestBLL();
05     List<TestModel> mList = bll.GetList();
06   
07     var query = from m in mList
08                 select m;
09   
10     var query1 = from m in mList
11                  where m.Id > 2
12                  select m;
13   
14     var query2 = from m in mList
15                  where m.Id > 2
16                  orderby m.Id descending 
17                  select m;
18   
19     var query3 = from m in mList
20                  orderby m.Posttime descending
21                  select m;
22   
23     var query4 = (from m in mList 
24                  select m).Take(3);
25   
26     var query5 = from m in mList
27                  orderby m.Name ascending
28                  select m;
29   
30     PrintList("from m in mList select m", query);
31     PrintList("from m in mList where m.Id > 2 select m", query1);
32     PrintList("from m in mList select m", query2);
33     PrintList("from m in mList orderby m.Posttime descending select m", query3);
34     PrintList("(from m in mList where select m).Take(3)", query4);
35     PrintList("from m in mList orderby m.Name ascending select m", query5);
36   
37     Console.ReadKey();
38   
39 }
40   
41 private static void PrintList(string expression, IEnumerable<TestModel> query)
42 {
43     Console.WriteLine("Query expression: " + expression);
44     Console.WriteLine("__________________________________________________________________");
45     foreach (var item in query)
46     {
47         Console.WriteLine(item.ToString());
48     }
49     Console.WriteLine("\n");
50 }

有图有真相：

 

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posted @ 2012-06-28 11:11  赤狐(zcm123)  阅读(2536)  评论(0)    收藏  举报