c#动态创建内存模型（笔记）

支持可为Null的模型属性：

基础：值类型是继承ValueType、对象类型是继承ObjectType;因此，我们只要看基类型属于那种就可以添加：“?”

    ///<summary>
    /// 动态创建内存模型
    ///</summary>
    public class CreateDnyModel
    {
        ///<summary>
        /// Dictionary {属性名称,属性类型}
        ///</summary>
        private Dictionary<string, Type> dicList = new Dictionary<string, Type>();
        ///<summary>
        /// 添加命名空间
        ///</summary>
        private List<string> namespaceList = new List<string>();
        //添加引用集合
        private List<string> assemblyList = new List<string>();
        public void Add(string columnName, Type columnType)
        {
            dicList.Add(columnName, columnType);
        }

        public void AddNamespace(string nameSpace)
        {
            if (!namespaceList.Contains(nameSpace))
                namespaceList.Add(nameSpace);
        }
        public void AddAssembly(string assembly)
        {
            if (!assemblyList.Contains(assembly))
                assemblyList.Add(assembly);
        }

        public object BuilderModel()
        {
            CodeDomProvider cdp = new CSharpCodeProvider(); //CodeDomProvider.CreateProvider("CSharp");
            CompilerParameters cp = new CompilerParameters();
            foreach (string assembly in assemblyList)
            {
                cp.ReferencedAssemblies.Add(assembly);
            }
            cp.ReferencedAssemblies.Add("System.dll");
            cp.GenerateExecutable = true;
            cp.GenerateInMemory = true;
            CompilerResults cr = cdp.CompileAssemblyFromSource(cp, BiulderCode()); //cdp.CompileAssemblyFromSource(cp, GetCSharpCode());
            if (cr.Errors.Count > 0)
            {
                return null;
            }
            Assembly asm = cr.CompiledAssembly;
            return asm.CreateInstance("MyDnyModel.DnyModel_Memory");
        }

        private string BiulderCode()
        {
            CodeDomProvider cdp = new CSharpCodeProvider();
            CodeCompileUnit codeCompileUnit = GetCodeCompileUnit();
            ICodeGenerator gen = cdp.CreateGenerator();
            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (StreamWriter stream = new StreamWriter(memoryStream))
                {
                    IndentedTextWriter tw = new IndentedTextWriter(stream, "");
                    ICodeGenerator ICG = cdp.CreateGenerator();
                    ICG.GenerateCodeFromCompileUnit(codeCompileUnit, tw, new CodeGeneratorOptions());
                }
                byte[] buf = memoryStream.ToArray();
                return Encoding.Default.GetString(buf);
            }
        }

        private CodeCompileUnit GetCodeCompileUnit()
        {
            CodeCompileUnit CompileUnit = new CodeCompileUnit();

            CodeNamespace MyDnyModel = new CodeNamespace("MyDnyModel");//创建命名空间
            CompileUnit.Namespaces.Add(MyDnyModel);

            foreach (string nameSpace in namespaceList)
            {
                MyDnyModel.Imports.Add(new CodeNamespaceImport(nameSpace));//导入框架的命名空间
            }

            CodeTypeDeclaration DnyModel_Memory = new CodeTypeDeclaration("DnyModel_Memory");//类型定义
            DnyModel_Memory.IsClass = true;
            MyDnyModel.Types.Add(DnyModel_Memory);

            string Null = string.Empty;
            foreach (var entry in dicList)
            {
                if (entry.Value.BaseType != typeof(ValueType))
                    Null = "";
                else
                    Null = " ? ";
                DnyModel_Memory.Members.Add(GetField(entry.Key, Null, entry.Value));
                DnyModel_Memory.Members.Add(GetFieldProperty(entry.Key, Null, entry.Value));
            }

            CodeMemberMethod main = new CodeMemberMethod();
            main.Name = "Main";
            main.ReturnType = new CodeTypeReference(typeof(void));
            main.Attributes = MemberAttributes.Public | MemberAttributes.Final | MemberAttributes.Static;
            DnyModel_Memory.Members.Add(main);

            CodeConstructor con = new CodeConstructor();//构造函数
            con.Attributes = MemberAttributes.Public;
            DnyModel_Memory.Members.Add(con);

            return CompileUnit;
        }

        private CodeMemberProperty GetFieldProperty(string columnName, string Null, Type columnType)
        {
            CodeMemberProperty member = new CodeMemberProperty();
            member.HasGet = true;
            member.HasSet = true;
            member.Attributes = MemberAttributes.Public | MemberAttributes.Final;
            member.Name = Null + columnName;
            member.Type = new CodeTypeReference(columnType);
            member.GetStatements.Add(new CodeMethodReturnStatement(new CodeFieldReferenceExpression(new CodeThisReferenceExpression(),
                                                                               "_" + columnName)));
            member.SetStatements.Add(
                new CodeAssignStatement(
                    new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), "_" + columnName),
                    new CodePropertySetValueReferenceExpression()));

            return member;
        }

        private CodeMemberField GetField(string columnName, string Null, Type columnType)
        {
            return new CodeMemberField(columnType, Null + "_" + columnName) { Attributes = MemberAttributes.Private };
        }
    }