将图元包含的点集合(IPointCollection)序列化为二进制保存到数据库

需求：

把图元包含的点集合按

 

点数

x1

y1

x2

y2

...

...

 

这样保存到byte[]数组中并存储到数据库(oracle的blob或sqlserver的image型)

IFeature ftr
ftr=......
IGeometry boundGeometry = ftr.Shape;
                    IPointCollection pointCollection = boundGeometry as IPointCollection;
int ptCount = pointCollection.PointCount;
byte[] bytePts = new byte[ptCount * 16+4];//blob前4位保存点数，后面保存点坐标
                    byte[] byteptCount = System.BitConverter.GetBytes(ptCount);
                    int lbc = byteptCount.Length;
                    byteptCount.CopyTo(bytePts, 0);
                    for (int i = 0; i < ptCount; i++)
                    {                      
                        byte[] bytept = System.BitConverter.GetBytes(pointCollection.get_Point(i).X);
                        bytept.CopyTo(bytePts,4+i*16);
                        bytept = System.BitConverter.GetBytes(pointCollection.get_Point(i).Y);
                        bytept.CopyTo(bytePts, 4 + i * 16+8);
                    }

开始是用string连接多个点坐标，用逗号分隔，然后转成byte数组，但这样的话，

byte数组就凭空大了一倍

在读取的时候还要转换类型，再分解，使用C++做这些操作比较麻烦(客户端是C++写的)

这样存储按位读取，速度效率都不错，记一下