抽象类的应用实例（一套代码处理dxf和dwg文件）——CAD c#二次开发

c# .net中，读取dwg文件的函数为：

db.ReadDwgFile(filePath, FileShare.Read, true, null);

读取dxf文件的方法为：

 db.DxfIn(filePath, null);

同理，另存为cad文件的方法也不同。当需要同事处理dwg和dxf文件时，则需要编写两套代码，会有大量的重复代码，这是可用抽象类。

 public abstract class CadMergerBase
 {
     protected abstract string FileExtension { get; }
     protected abstract void ReadFile(Database db, string filePath);
     protected abstract void SaveResult(Database db, string outputPath);

     public void MergeFiles()
     {
         Database currentDb = HostApplicationServices.WorkingDatabase;
         Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;

         try
         {
              ReadFile(tempDb, file);

             // 保存结果
             SaveResult(currentDb, outputPath);

             
         }
         catch (Exception ex)
         {
             ed.WriteMessage($"\n发生严重错误：{ex.Message}");
         }
     }
}

public class DwgMerger : CadMergerBase
{
    protected override string FileExtension => ".dwg";

    protected override void ReadFile(Database db, string filePath)
    {
        db.ReadDwgFile(filePath, FileShare.Read, true, null);
    }

    protected override void SaveResult(Database db, string outputPath)
    {
        db.SaveAs(outputPath, DwgVersion.Current);
    }

    [CommandMethod("MergeDWG")]
    public void MergeDwgCommand() => MergeFiles();
}

public class DxfMerger : CadMergerBase
{
    protected override string FileExtension => ".dxf";

    protected override void ReadFile(Database db, string filePath)
    {
        db.DxfIn(filePath, null);
    }

    protected override void SaveResult(Database db, string outputPath)
    {
        db.DxfOut(outputPath, 16, false);
    }

    [CommandMethod("MergeDXF")]
    public void MergeDxfCommand() => MergeFiles();
}

 public void MergeFiles()
 {
     Database currentDb = HostApplicationServices.WorkingDatabase;
     Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
     ProcessFiles(currentDb, ed, fileNames, addFileName, ref successCount, failedFiles);
     // 保存结果
     SaveResult(currentDb, outputPath);
 }

private void ProcessFiles(Database db, Editor ed, List<string> files,
    bool addFileName, ref int successCount, List<string> failedFiles)
{
    // 读取文件
    ReadFile(tempDb, file);
    // 插入图形
    InsertEntity(db, tempDb, insertPoint, extents);
}