属性很多时如何很清晰的通过充血模型创建数据合法的对象

原因：在构建充血模型时，为构建合法的对象，对象赋值都在私有的。属性少的时候可以直接写构造函数，属性多时就不太合适了。

如何解决这个问题呢？直接上代码

Book类：

 1 public class Book
 2     {
 3         public long Id { get; private set; }
 4         public long AuthorId { get; private set; }
 5         public string Name { get; private set; }
 6         public string Code { get; private set; }
 7         public DateTime PubTime { get; private set; }
 8         public string Publisher { get; private set; }
 9 
10         private Book()
11         {
12 
13         }
14 
15         /// <summary>
16         /// 声明嵌套类型
17         /// </summary>
18         public class Builder
19         {
20             private long Id;
21             private long AuthorId;
22             private string Name;
23             private string Code;
24             private DateTime PubTime;
25             private string Publisher;
26 
27             public Builder SetId(long id)
28             {
29                 this.Id = id;
30                 return this;
31             }
32             public Builder SetName(string name)
33             {
34                 this.Name = name;
35                 return this;
36             }
37             public Builder SetAuthorId(long authorId)
38             {
39                 this.AuthorId = authorId;
40                 return this;
41             }
42             public Builder SetCode(string code)
43             {
44                 this.Code = code;
45                 return this;
46             }
47             public Builder SetPubTime(DateTime pubTime)
48             {
49                 this.PubTime = pubTime;
50                 return this;
51             }
52             public Builder SetPublisher(string publisher)
53             {
54                 this.Publisher = publisher;
55                 return this;
56             }
57             public Book Build()
58             {
59                 if (Id == 0)
60                 {
61                     throw new ArgumentNullException("id");
62                 }
63                 if (AuthorId == 0)
64                 {
65                     throw new ArgumentNullException("AutorId");
66                 }
67                 var book = new Book();
68                 book.Id = Id;
69                 book.AuthorId = AuthorId;
70                 book.Name = Name;
71                 book.Code = Code;
72                 book.PubTime = PubTime;
73                 book.Publisher = Publisher;
74                 return book;
75             }
76         }
77     }

1 //链式编程 构建合法的Book类
2 Book.Builder builder = new Book.Builder();
3             var book = builder.SetId(1).SetAuthorId(1).SetCode("ddf").
4                 SetName("jisdjfoisjf").SetPublisher("122").SetPubTime(DateTime.Now)
5                 .Build();

数据校验都放在builder.Build方法中