C# AutoCAD2010选择dwg中的一个块，获取其位置，再选择一个外部块在该位置去替换它，完整代码

下面是一份示例代码，你可以根据自己的需求进行修改和优化：

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;

namespace ReplaceBlock
{
    public class Commands
    {
        [CommandMethod("ReplaceBlock")]
        public void ReplaceBlock()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            PromptEntityOptions peo1 = new PromptEntityOptions("\n选择要替换的块：");
            peo1.SetRejectMessage("\n请选择块实体！");
            peo1.AddAllowedClass(typeof(BlockReference), true);
            PromptEntityResult per1 = ed.GetEntity(peo1);

            if (per1.Status != PromptStatus.OK) return;

            BlockReference blkRef1 = (BlockReference)per1.ObjectId.GetObject(OpenMode.ForRead);
            Point3d blkPos = blkRef1.Position;

            PromptEntityOptions peo2 = new PromptEntityOptions("\n选择替换块的位置：");
            peo2.SetRejectMessage("\n请选择点实体！");
            peo2.AddAllowedClass(typeof(DBPoint), true);
            PromptEntityResult per2 = ed.GetEntity(peo2);

            if (per2.Status != PromptStatus.OK) return;

            DBPoint pt = (DBPoint)per2.ObjectId.GetObject(OpenMode.ForRead);
            Point3d ptPos = pt.Position;

            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);

                BlockReference blkRef2 = new BlockReference(ptPos, blkRef1.BlockTableRecord);
                blkRef2.ScaleFactors = blkRef1.ScaleFactors;
                blkRef2.Rotation = blkRef1.Rotation;

                btr.AppendEntity(blkRef2);
                tr.AddNewlyCreatedDBObject(blkRef2, true);

                foreach (ObjectId arId in blkRef1.AttributeCollection)
                {
                    AttributeReference ar = (AttributeReference)tr.GetObject(arId, OpenMode.ForRead);
                    AttributeReference arNew = new AttributeReference();
                    arNew.SetAttributeFromBlock(ar, blkRef2.BlockTransform);
                    arNew.Position = ar.Position.TransformBy(blkRef2.BlockTransform);
                    arNew.TextString = ar.TextString;
                    blkRef2.AttributeCollection.AppendAttribute(arNew);
                    tr.AddNewlyCreatedDBObject(arNew, true);
                }

                blkRef1.Erase();
                tr.Commit();
                ed.Regen();
            }
        }
    }
}

这段代码实现了选择一个块，获取其位置，再选择一个点，将另一个块替换到该位置的功能。需要注意的是，代码中的块替换是完全按照被替换块的属性来进行的，包括位置、缩放比例和旋转角度，同时也会复制被替换块中的属性并应用到新块上。