C# 动态生成实体类代码

生成实体类代码通常是为了避免手动编写大量重复的代码，提高开发效率和代码质量。C#可以使用反射和代码生成来动态生成实体类代码。

在使用反射生成实体类代码时，可以通过反射获取实体类的字段信息，然后使用代码生成的方式生成实体类代码。以下是一个简单的示例：

using System;
using System.Reflection;
using System.CodeDom;
using System.CodeDom.Compiler;
using Microsoft.CSharp;

namespace DynamicEntity
{
    class Program
    {
        static void Main(string[] args)
        {
            // 创建 CodeCompileUnit 对象
            CodeCompileUnit compileUnit = new CodeCompileUnit();

            // 添加命名空间
            CodeNamespace codeNamespace = new CodeNamespace("DynamicEntity");
            compileUnit.Namespaces.Add(codeNamespace);

            // 添加引用
            codeNamespace.Imports.Add(new CodeNamespaceImport("System"));

            // 创建类
            CodeTypeDeclaration classDeclaration = new CodeTypeDeclaration("Person");
            classDeclaration.IsClass = true;
            classDeclaration.TypeAttributes = TypeAttributes.Public;

            // 添加字段
            CodeMemberField field1 = new CodeMemberField(typeof(int), "_id");
            field1.Attributes = MemberAttributes.Private;
            classDeclaration.Members.Add(field1);

            CodeMemberField field2 = new CodeMemberField(typeof(string), "_name");
            field2.Attributes = MemberAttributes.Private;
            classDeclaration.Members.Add(field2);

            // 添加属性
            CodeMemberProperty property1 = new CodeMemberProperty();
            property1.Attributes = MemberAttributes.Public | MemberAttributes.Final;
            property1.Name = "Id";
            property1.Type = new CodeTypeReference(typeof(int));
            property1.GetStatements.Add(new CodeMethodReturnStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "_id")));
            property1.SetStatements.Add(new CodeAssignStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "_id"), new CodePropertySetValueReferenceExpression()));
            classDeclaration.Members.Add(property1);

            CodeMemberProperty property2 = new CodeMemberProperty();
            property2.Attributes = MemberAttributes.Public | MemberAttributes.Final;
            property2.Name = "Name";
            property2.Type = new CodeTypeReference(typeof(string));
            property2.GetStatements.Add(new CodeMethodReturnStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "_name")));
            property2.SetStatements.Add(new CodeAssignStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "_name"), new CodePropertySetValueReferenceExpression()));
            classDeclaration.Members.Add(property2);

            // 添加类到命名空间
            codeNamespace.Types.Add(classDeclaration);

            // 生成代码
            CSharpCodeProvider provider = new CSharpCodeProvider();
            CodeGeneratorOptions options = new CodeGeneratorOptions();
            options.BracingStyle = "C";
            string fileName = "Person.cs";
            using (System.IO.StreamWriter sourceWriter = new System.IO.StreamWriter(fileName))
            {
                provider.GenerateCodeFromCompileUnit(compileUnit, sourceWriter, options);
            }

            Console.WriteLine("代码已生成到文件：{0}", fileName);
            Console.ReadKey();
        }
    }
}

运行上述代码后，会生成一个名为“Person.cs”的文件，内容如下：

namespace DynamicEntity {
    using System;
    
    public class Person {
        
        private int _id;
        
        private string _name;
        
        public virtual int Id {
            get {
                return this._id;
            }
            set {
                this._id = value;
            }
        }
        
        public virtual string Name {
            get {
                return this._name;
            }
            set {
                this._name = value;
            }
        }
    }
}

这是一个简单的实体类代码，包含了两个字段和对应的属性。可以根据实际需求来动态生成更加复杂的实体类代码。