java 如何看cad图纸的源代码

Java可以通过调用CAD文件的开放式API接口，将CAD图纸导入到Java项目中进行展示、分析和编辑。这需要使用支持CAD文件的第三方Java库，如AutoCAD Java API、dwgPlotX Java Edition和CADSoftTools Java API等。

有关AutoCAD Java API的示例代码如下：

import com.autodesk.autocad.application.IAcadApplication;
import com.autodesk.autocad.databaseServices.BlockTable;
import com.autodesk.autocad.databaseServices.Database;
import com.autodesk.autocad.databaseServices.DBObject;
import com.autodesk.autocad.databaseServices.DBObjectIterator;
import com.autodesk.autocad.databaseServices.DwgFileHandle;
import com.autodesk.autocad.databaseServices.Entity;
import com.autodesk.autocad.databaseServices.LayerTable;
import com.autodesk.autocad.databaseServices.Layout;
import com.autodesk.autocad.databaseServices.ModelSpace;
import com.autodesk.autocad.databaseServices.ObjectId;
import com.autodesk.autocad.databaseServices.Polyline;
import com.autodesk.autocad.databaseServices.Polyline2d;
import com.autodesk.autocad.databaseServices.Polyline3d;
import com.autodesk.autocad.databaseServices.Viewport;
import com.autodesk.autocad.geometry.Point2d;
import com.autodesk.autocad.geometry.Point3d;
import com.autodesk.autocad.runtime.ErrorStatus;
import com.autodesk.autocad.runtime.ExtensionDictionary;
import com.autodesk.autocad.runtime.Interop;
import com.autodesk.autocad.runtime.ResultBuffer;
import com.autodesk.autocad.runtime.Variant;

public class AutoCADDrawing {
   public static void main(String[] args) {
      IAcadApplication app = null;
      try {
         app = Interop.getAcadApplication();
         if (app != null) {
            Database db = app.getDocumentManager().getActiveDatabase();
            BlockTable bt = db.getBlockTableId().open(BlockTable.class, false);
            Entity ent = null;
            Polyline plc = null;
            Polyline2d p2d = null;
            Polyline3d p3d = null;
            LayerTable lt = db.getLayerTableId().open(LayerTable.class, false);
            Layout lo = db.getLayout("Model");
            ObjectId objId = lo.getObjectId();
            ModelSpace ms = objId.open(ModelSpace.class, false);
            Viewport vp = null;
            DBObjectIterator vit = null;
            DBObject obj = null;
            ExtensionDictionary ed = null;
            ResultBuffer rb = null;
            Variant vDrawingScale = null;
            String sLayerName = null;
            int iColor = -1;
            short iLineWeight = -1;
            Point3d pt1 = null, pt2 = null;
            Point2d p2dfst = null, p2dscd = null;
            System.out.println("Blocks in drawing:");
            for (ObjectId id : bt) {
               System.out.println(id.getHandle());
            }
            System.out.println("Layers in drawing:");
            for (ObjectId id : lt) {
               System.out.println(id.getHandle());
            }
            System.out.println("Entities in ModelSpace:");
            vit = ms.newObjectIterator();
            while (vit.hasNext()) {
               obj = vit.next();
               if (obj instanceof Polyline) {
                  plc = (Polyline) obj;
                  System.out.println("Polyline found on Layer: "
                        + plc.getLayer());
                  System.out.println("Polyline vertices:");
                  for (int i = 0; i < plc.getNumberOfVertices(); i++) {
                     pt2 = plc.getPointAt(i);
                     System.out.println("Vertex " + i + ": (" + pt2.getX()
                           + "," + pt2.getY() + ")");
                  }
               } else if (obj instanceof Polyline2d) {
                  p2d = (Polyline2d) obj;
                  System.out.println("Polyline2d found on Layer: "
                        + p2d.getLayer());
                  System.out.println("Polyline2d vertices:");
                  for (int i = 0; i < p2d.getNumberOfVertices(); i++) {
                     p2dfst = p2d.getVertexAt(i);
                     System.out.println("Vertex " + i + ": ("
                           + p2dfst.getX() + "," + p2dfst.getY() + ")");
                  }
               } else if (obj instanceof Polyline3d) {
                  p3d = (Polyline3d) obj;
                  System.out.println("Polyline3d found on Layer: "
                        + p3d.getLayer());
                  System.out.println("Polyline3d vertices:");
                  for (int i = 0; i < p3d.getNumberOfVertices(); i++) {
                     pt2 = p3d.getPointAt(i);
                     System.out.println("Vertex " + i + ": (" + pt2.getX()
                           + "," + pt2.getY() + "," + pt2.getZ() + ")");
                  }
               } else if (obj instanceof Viewport) {
                  vp = (Viewport) obj;
                  System.out.println("Viewport found on Layer: "
                        + vp.getLayer());
                  System.out.println("Viewport position and size: "
                        + vp.getLowerLeftCorner().toString() + ", "
                        + vp.getUpperRightCorner().toString());
               } else {
                  System.out.println(obj.getHandle() + ": "
                        + obj.getClass().getName());
               }
            }
         }
      } catch (UnsatisfiedLinkError e) {
         System.out.println("AutoCAD isn't running");
      } catch (ErrorStatus e) {
         System.out.println(e.name());
      } finally {
         if (app != null) {
            DwgFileHandle dwg = app.getActiveDocument().getDwgFileHandle();
            System.out.println("Drawing name is " + dwg.getFileName());
         }
      }
   }
}

该示例代码利用AutoCAD Java API遍历了当前AutoCAD文档中的块、图层、布局、视口和实体，并获取了它们的属性和坐标信息，可以为Java开发人员提供了一种方便快捷的方式来解析和操作CAD图纸。