(转)简单代码生成器原理剖析（二）

原文地址：http://www.cnblogs.com/OceanEyes/archive/2012/03/08/codebuilder.html

上篇《简单代码生成器原理剖析（一）》分析了代码生成器的原理，查询数据库系统视图：INFORMATION_SCHEMA.TABLES、 INFORMATION_SCHEMA.COLUMNS 可以获得数据库中表、列的相关信息，再运用StringBuilder类的其AppendLine方法追加字符串，最后早运用File.WriteAllText方法将字符串写入文件。

第二版代码生成器在第一版的基础上扩展了以下功能：

使用了部分类（partial）：当使用大项目或自动生成的代码（如由 Windows 窗体设计器提供的代码）时，将一个类、结构或接口类型拆分到多个文件中的做法就很有用。分部类型可能包含分部方法。
使用可空类型：由于数据库中表中数据很有可能是NULL，可空类型使得数据从表中读取出来赋值给值类型更加兼容。
增加了ToModel方法：将数据库表中一行数据封装成Model类的对象返回。

Model的实现：

        /// <summary>/// Model/// </summary>        public static void CreateModel(CodeBuilderArgs args,string tableName)        {            DataTable dt = ExecuteDataTable(args.ConnectionString, "select * from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME=@TABLE_NAME"                ,new SqlParameter("TABLE_NAME",tableName));            StringBuilder sb = new StringBuilder();            sb.AppendLine("using System;");            sb.AppendLine("using System.Collections.Generic;");            sb.AppendLine("using System.Linq;");            sb.AppendLine("using System.Text;");            sb.AppendLine("namespace " + args .Namespace+ ".Model");            sb.AppendLine("{");            sb.AppendLine("partial class " + tableName);            sb.AppendLine("{");foreach (DataRow row in dt.Rows)            {string colName = Convert.ToString(row["COLUMN_NAME"]);string colType = Convert.ToString(row["DATA_TYPE"]);

                Type netType = GetTypeByDBType(colType);string netTypeName;if (netType.IsValueType)                {                    netTypeName = netType + "?";                }else                {                    netTypeName = netType.ToString();                }                sb.AppendLine("public " +netTypeName +" "+ colName + " { get; set; }");            }            sb.AppendLine(" }");            sb.AppendLine(" }");string modelDir = Path.Combine(args.OutputDir, "Model");string modelFile = Path.Combine(modelDir, tableName+".cs");            Directory.CreateDirectory(modelDir);            File.WriteAllText(modelFile, sb.ToString());        }

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DAL（数据访问层）的实现：

        /// <summary>///DAL/// </summary>/// <param name="args"></param>/// <param name="tableName"></param>        public static void CreateDAL(CodeBuilderArgs args, string tableName)        {            StringBuilder sb = new StringBuilder();            DataTable dt = ExecuteDataTable(args.ConnectionString, "select * from INFORMATION_SCHEMA.COLUMNS where TABLE_NAME=@TABLE_NAME"    , new SqlParameter("TABLE_NAME", tableName));            sb.AppendLine("using System;");            sb.AppendLine("using System.Collections.Generic;");            sb.AppendLine("using System.Linq;");            sb.AppendLine("using System.Text;");            sb.AppendLine("using "+args.Namespace+".Model;");            sb.AppendLine("using System.Data.SqlClient;");            sb.AppendLine("using System.Data;");            sb.AppendLine("namespace "+args.Namespace+".DAL");            sb.AppendLine("{");            sb.AppendLine("partial class "+tableName+"DAL");            sb.AppendLine("{");            sb.AppendLine("public int AddNew("+tableName+" model)");            sb.AppendLine("{");

string[] cols = GetColsWithoutId(GetCols(dt, new List<string>())).ToArray();var colsParameters=from e in cols select"@"+ e;            sb.AppendLine("string sql = \"insert into " + tableName + "(" + string.Join(",", cols) + ") output inserted.id values(" + string.Join(",", colsParameters.ToArray()) + ")\";");            sb.AppendLine("int id = (int)SqlHelper.ExecuteScalar(sql");

foreach (DataRow row in dt.Rows)            {string colName = Convert.ToString(row["COLUMN_NAME"]);if(!(colName.ToLower()=="id"))                {                  sb.AppendLine(", new SqlParameter(\""+colName+"\", model."+colName+")");                   }

            }            sb.AppendLine(");");            sb.AppendLine("return id;");            sb.AppendLine("}");

var par=from e in cols select e+"="+"@"+e;            sb.AppendLine("public bool Update("+tableName+" model)");            sb.AppendLine("{");            sb.AppendLine("string sql = \"update "+tableName+" set "+string.Join(",",par.ToArray())+" where id=@id\";");            sb.AppendLine("int rows = SqlHelper.ExecuteNonQuery(sql");foreach (DataRow row in dt.Rows)            {string colName = Convert.ToString(row["COLUMN_NAME"]);                sb.AppendLine(", new SqlParameter(\"" + colName + "\", model." + colName + ")");               }            sb.AppendLine(");");            sb.AppendLine("return rows>0;");            sb.AppendLine("}");

            sb.AppendLine("public bool Delete(int id)");            sb.AppendLine("{");            sb.AppendLine("int rows = SqlHelper.ExecuteNonQuery(\"delete from "+tableName+" where id=@id\",");            sb.AppendLine("new SqlParameter(\"id\", id));");            sb.AppendLine("return rows > 0;");            sb.AppendLine("}");

            sb.AppendLine("private static "+tableName+" ToModel(DataRow row)");            sb.AppendLine("{");            sb.AppendLine(""+tableName+" model = new "+tableName+"();");foreach (DataRow row in dt.Rows)            {string colName = Convert.ToString(row["COLUMN_NAME"]);string colType = Convert.ToString(row["DATA_TYPE"]);

                Type netType = GetTypeByDBType(colType);string netTypeName;if (netType.IsValueType)                {                    netTypeName = netType + "?";                }else                {                    netTypeName = netType.ToString();                }                sb.AppendLine("model."+colName+" = row.IsNull(\""+colName+"\") ? null : "+"("+netTypeName+")"+"row[\""+colName+"\"];");            }            sb.AppendLine("return model;");            sb.AppendLine("}");

//            sb.AppendLine("public "+tableName+" Get(int id)");            sb.AppendLine("{");            sb.AppendLine("DataTable dt = SqlHelper.ExecuteDataTable(\"select * from "+tableName+"  where id=@id\",");            sb.AppendLine("new SqlParameter(\"id\", id));");            sb.AppendLine("if(dt.Rows.Count > 1)");            sb.AppendLine("{");            sb.AppendLine("throw new Exception(\"more than 1 row was found\");");            sb.AppendLine("}");            sb.AppendLine("if(dt.Rows.Count <= 0)");            sb.AppendLine("{");            sb.AppendLine("return null; ");            sb.AppendLine("}");            sb.AppendLine("DataRow row = dt.Rows[0];");            sb.AppendLine(""+tableName+" model = ToModel(row);");            sb.AppendLine("return model;");            sb.AppendLine("}");

            sb.AppendLine("public IEnumerable<"+tableName+">ListAll()");            sb.AppendLine("{");            sb.AppendLine("List<"+tableName+"> list = new List<"+tableName+">();");            sb.AppendLine("DataTable dt = SqlHelper.ExecuteDataTable(\"select * from "+tableName+"\");");            sb.AppendLine("foreach (DataRow row in dt.Rows)");            sb.AppendLine("{");            sb.AppendLine("list.Add(ToModel(row));");            sb.AppendLine("}");            sb.AppendLine("return list;");            sb.AppendLine("}");            sb.AppendLine("}");            sb.AppendLine("}");

string DALlDir = Path.Combine(args.OutputDir,"DAL");string DALFile = Path.Combine(DALlDir,tableName+"DAL.cs");            Directory.CreateDirectory(DALlDir);            File.WriteAllText(DALFile,sb.ToString());        }private static IEnumerable<string> GetColsWithoutId(List<string> cols)        {var colArray = from col in cols where col.ToLower() != "id" select col;return colArray;        }private static List<string> GetCols(DataTable dt, List<string> cols)        {foreach (DataRow row in dt.Rows)            {string colName = Convert.ToString(row["COLUMN_NAME"]);                cols.Add(colName);            }return cols;        }

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BLL的实现：

        /// <summary>/// BLL/// </summary>/// <param name="args"></param>/// <param name="tableName"></param>        public static void CreateBLL(CodeBuilderArgs args,string tableName)        {            StringBuilder sb = new StringBuilder();            sb.AppendLine("using System;");            sb.AppendLine("using System.Collections.Generic;");            sb.AppendLine("using System.Linq;");            sb.AppendLine("using System.Text;");            sb.AppendLine("using "+args.Namespace+".Model;");            sb.AppendLine("using "+args.Namespace+".DAL;");            sb.AppendLine("namespace "+args.Namespace+".BLL");            sb.AppendLine("{");            sb.AppendLine("partial class "+tableName+"BLL");            sb.AppendLine("{");            sb.AppendLine("public int AddNew("+tableName+" model)");            sb.AppendLine("{");            sb.AppendLine("return new "+tableName+"DAL().AddNew(model);");            sb.AppendLine("}");            sb.AppendLine("public bool Delete(int id)");            sb.AppendLine("{");            sb.AppendLine("return new "+tableName+"DAL().Delete(id);");            sb.AppendLine("}");            sb.AppendLine("public bool Update("+tableName+" model)");            sb.AppendLine("{");            sb.AppendLine("return new "+tableName+"DAL().Update(model);");            sb.AppendLine("}");            sb.AppendLine("public "+tableName+" Get(int id)");            sb.AppendLine("{");            sb.AppendLine("return new "+tableName+"DAL().Get(id);");            sb.AppendLine("}");            sb.AppendLine("public IEnumerable<"+tableName+"> ListAll()");            sb.AppendLine("{");            sb.AppendLine("return new "+tableName+"DAL().ListAll();");            sb.AppendLine("}");            sb.AppendLine("}");            sb.AppendLine("}");string BLLDir = Path.Combine(args.OutputDir,"BLL");string BLLFile = Path.Combine(BLLDir,tableName+"BLL.cs");            Directory.CreateDirectory(BLLDir);            File.WriteAllText(BLLFile,sb.ToString());        }

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详细代码可参考：

http://www.oksvn.com/Project/Detail-11919.shtml

转载于:https://www.cnblogs.com/fcsh820/archive/2012/03/15/2398470.html

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