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简单代码生成器原理剖析(二)

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2021-09-29 00:34:28 / 113 阅读 / 正在检测是否收录...

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:
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        /// <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:
 
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        /// <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:
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        /// <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:
88x31.png

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分类: 架构思想

本文转自木宛城主博客园博客,原文链接:http://www.cnblogs.com/OceanEyes/archive/2012/03/08/codebuilder.html,如需转载请自行联系原作者

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