VS c# 操作 Microsoft Project mpp 文件 并遍历边关系

网上找到资料提供了遍历.mpp文件中任务的功能：

http://blog.csdn.net/gxf36/article/details/5253792

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但未提供遍历任务边关系（依赖关系）的功能。尝试并经过测试形成如下代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Office.Interop.MSProject;

namespace JDPrj_Demo_DataTransfm
{
    class MppIO
    {
         /// <summary>
        /// 获取.mpp文件中所有依赖关系
        /// </summary>
        /// <param name="filepath"></param>
        /// <returns></returns>
        public List<Edge> getEdges(string filepath)
        {
            List<Edge> list = new List<Edge>();
            Object missing = Type.Missing;
            ApplicationClass prj = new ApplicationClass();
            prj.FileOpen(filepath, missing, missing, missing, missing, missing, missing, missing, missing, missing, missing, PjPoolOpen.pjPoolReadWrite, missing, missing, missing, missing);
            Edge edge = null;
            int graph = new Random().Next(100000);
            //遍历所有工程
            foreach (Project proj in prj.Projects)
            {
                //遍历所有任务
                foreach (Microsoft.Office.Interop.MSProject.Task task in proj.Tasks)
                {
                    //遍历任务的依赖关系(边关系)
                    foreach (TaskDependency dep in task.TaskDependencies)
                    {
                        //.mpp任务采用双向链表的方式存储边关系
                        //只取边的起始任务为当前任务的边，去重
                        if (dep.From.Index == task.Index)
                        {
                            edge = new Edge(graph, dep.From.Index, dep.To.Index, 0);
                            list.Add(edge);
                            //根据需要只需去双向链表的一条边，去重
                            break;
                        }
                    }
                }
            }
            return list;
        }

    }

    /// <summary>
    /// 边，任务与任务间，节点与节点间的边
    /// </summary>
    public class Edge
    {
        public int graph_id = 0;    //图编号
        public int start_node = 0;  //开始节点
        public int end_node = 0;    //结束节点
        public int weight = 0;      //边权重
        public Edge() { }
        public Edge(int graph_id, int start_node, int end_node, int weight)
        {
            this.graph_id = graph_id;
            this.start_node = start_node;
            this.end_node = end_node;
            this.weight = weight;
        }
    }
}