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

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上篇《簡單代碼生成器原理剖析（一）》分析了代碼生成器的原理，查詢數據庫系統視圖：INFORMATION_SCHEMA.TABLES、 INFORMATION_SCHEMA.COLUMNS? 可以獲得數據庫中表、列的相關信息，再運用StringBuilder類的其AppendLine方法追加字符串，最后早運用File.WriteAllText方法將字符串寫入文件。

第二版代碼生成器在第一版的基礎上擴展了以下功能：

• 使用了部分類（partial）：當使用大項目或自動生成的代碼（如由 Windows 窗體設計器提供的代碼）時，將一個類、結構或接口類型拆分到多個文件中的做法就很有用。 分部類型可能包含分部方法。
• 使用可空類型：由于數據庫中表中數據很有可能是NULL，可空類型使得數據從表中讀取出來賦值給值類型更加兼容。
• 增加了ToModel方法：將數據庫表中一行數據封裝成Model類的對象返回。

Model的實現： /// <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());
}復制代碼DAL（數據訪問層）的實現： /// <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;
}復制代碼BLL的實現： /// <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());
}復制代碼詳細代碼可參考：http://www.oksvn.com/Project/Detail-11919.shtml

轉載于:https://www.cnblogs.com/fcsh820/archive/2012/03/15/2398470.html

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