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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public class TestBLL 

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{ 

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    public List<TestModel> GetList() 

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    { 

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        return new List<TestModel>() 

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        { 

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            new TestModel(){ Id=1, Name="RYWE", Content="IOJADJ", Posttime=DateTime.Now.AddHours(1) }, 

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            new TestModel(){ Id=2, Name="JGFA", Content="CAFYRE", Posttime=DateTime.Now.AddHours(0) }, 

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            new TestModel(){ Id=4, Name="PIOU", Content="OVXZLA", Posttime=DateTime.Now.AddHours(5) }, 

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            new TestModel(){ Id=5, Name="OUIH", Content="AIPJLM", Posttime=DateTime.Now.AddHours(3) }, 

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            new TestModel(){ Id=7, Name="ZCXI", Content="KUQOPA", Posttime=DateTime.Now.AddHours(7) } 

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        }; 

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    } 

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} 

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public class TestModel 

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{ 

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    public int Id { get; set; } 

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    public string Name { get; set; } 

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    public string Content { get; set; } 

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    public DateTime Posttime { get; set; } 

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    public TestModel() 

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    { 

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    } 

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    public override string ToString() 

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    { 

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        StringBuilder sb = new StringBuilder(); 

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        sb.Append(String.Format("{0}={1}, ", "Id", this.Id)); 

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        sb.Append(String.Format("{0}={1}, ", "Name", this.Name)); 

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        sb.Append(String.Format("{0}={1}, ", "Content", this.Content)); 

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        sb.Append(String.Format("{0}={1}", "Posttime", this.Posttime)); 

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        return sb.ToString(); 

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    } 

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}

测试代码：

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static void Main(string[] args) 

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{ 

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    TestBLL bll = new TestBLL(); 

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    List<TestModel> mList = bll.GetList(); 

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    var query = from m in mList 

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                select m; 

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    var query1 = from m in mList 

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                 where m.Id > 2 

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                 select m; 

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    var query2 = from m in mList 

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                 where m.Id > 2 

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                 orderby m.Id descending  

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                 select m; 

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    var query3 = from m in mList 

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                 orderby m.Posttime descending 

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                 select m; 

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    var query4 = (from m in mList  

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                 select m).Take(3); 

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    var query5 = from m in mList 

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                 orderby m.Name ascending 

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                 select m; 

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    PrintList("from m in mList select m", query); 

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    PrintList("from m in mList where m.Id > 2 select m", query1); 

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    PrintList("from m in mList select m", query2); 

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    PrintList("from m in mList orderby m.Posttime descending select m", query3); 

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    PrintList("(from m in mList where select m).Take(3)", query4); 

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    PrintList("from m in mList orderby m.Name ascending select m", query5); 

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    Console.ReadKey(); 

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} 

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private static void PrintList(string expression, IEnumerable<TestModel> query) 

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{ 

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    Console.WriteLine("Query expression: " + expression); 

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    Console.WriteLine("__________________________________________________________________"); 

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    foreach (var item in query) 

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    { 

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        Console.WriteLine(item.ToString()); 

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    } 

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    Console.WriteLine("\n"); 

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}

有图有真相：

Linq处理List数据

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