arcengine 开发几个注意释放内存的地方

在循环、查询过程中经常出现如下错误： 

1 、循环的 游标一定要释放不然会报错。

   private void find_allroads_lxbm(IFeature feature_ld, string lxbm)
        {
            try
            {
                ISpatialFilter spatialfilter = new SpatialFilterClass();
                spatialfilter.WhereClause = "[LXBM] = " + lxbm;
                spatialfilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;
                //feature_ld该路段 feature_last下一路段
                while (feature_ld != null)
                {
                    IPolyline polyline = feature_ld.Shape as IPolyline;
                    //缓冲
                    IPoint end_pt = polyline.ToPoint;
                    ITopologicalOperator topo2 = end_pt as ITopologicalOperator;
                    IGeometry geo_buffer_end = topo2.Buffer(1);
                    spatialfilter.Geometry = geo_buffer_end;
                    IFeatureCursor featcursor_lastld = m_featcls.Search(spatialfilter, true);
                    IFeature feature_last = featcursor_lastld.NextFeature();
                    try
                    {
                        while (feature_last != null)
                        {
                         
                           /****省略***/
                                                 
                        }
                    }
                    catch (Exception exx)
                    {
                        
                        MessageBox.Show(exx.ToString());
                    }
                  
                    //下一个
                    feature_ld = feature_last;
                   
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(featcursor_lastld);
                   
                }


                System.Runtime.InteropServices.Marshal.ReleaseComObject(spatialfilter);
                ////垃圾回收
                System.GC.Collect();
                System.GC.WaitForPendingFinalizers();
            }
            catch (Exception exx)
            {

                MessageBox.Show(exx.ToString());
            }           
        }  

2 关于查询（ISpatialFilter，IQueryFilter）：

 //该路线编码路段数量
            IQueryFilter queryfilterall = new QueryFilterClass();
            queryfilterall.WhereClause = " [LXBM]= "+ lxbm;
            LDBM_MAXCOUNT = m_featcls.FeatureCount(queryfilterall);
            //起始值
            start_index = Convert.ToInt32(start_lxh);
            IQueryFilter queryfilter = new QueryFilterClass();
            queryfilter.WhereClause = " [LDBM]= "+ start_ldbm;
            IFeatureCursor featcursor = m_featcls.Search(queryfilter, true);//最好是true

参考：http://www.cnblogs.com/gisoracle/archive/2012/01/28/2330541.html

为true分析：pFeatures集合存储了指向FeatureClass上所有Feature的引用，但是由于Recycling参数设置为TRUE也就是说每执行一个NextFeautre方法上一条记录的Feature值在内存中被回收，所以到最后遍历pFeatures集合的时候所有的IFeature引用指向的Feature对象都为Null。

未false分析：分析：pFeatures集合存储了指向FeatureClass上所有Feature的引用，但是由于Recycling参数设置为False也就是说每执行一个NextFeautre方法上一条记录的Feature值在内存中依然存在，所以到最后遍历pFeatures集合的时候所有的IFeature引用指向的Feature对象都依然存在。所以会执行的很Happy（如下图所示）：

转载自：https://mtr-1.oss-cn-beijing.aliyuncs.com/qyblog/2019/04/54376726.jpg