unity 断点续传

using UnityEngine;using System.Collections;using System;using System.Net;using System.IO;public class Load : MonoBehaviour {    AsyncOperation l;    void Start () {       // Application.backgroundLoadingPriority = ThreadPriority.Low;       // l =  Application.LoadLevelAsync("game");        StartCoroutine(FPointDown("http://127.0.0.1:8888/index.rar", "d:/a.rar"));        StartCoroutine(FPointDown(@"http://dl_dir.qq.com/qqfile/qq/QQ2012/QQ2012Beta3.exe", "d:/qq.rar"));            }        void OnGUI () {        GUILayout.Button(t);    }    void OnApplicationQuit()    {        print("stop");        StopCoroutine("FPointDown");    }    string t = "";    IEnumerator  downfile(string url, string LocalPath)    {            Uri u = new Uri(url);            HttpWebRequest mRequest = (HttpWebRequest)WebRequest.Create(u);            mRequest.Method = "GET";            mRequest.ContentType = "application/x-www-form-urlencoded";            HttpWebResponse wr = (HttpWebResponse)mRequest.GetResponse();            Stream sIn = wr.GetResponseStream();            FileStream fs = new FileStream(LocalPath, FileMode.Create, FileAccess.Write);            long length = wr.ContentLength;            long i = 0;            decimal j = 0;            while (i < length)            {                byte[] buffer = new byte[1024];                i += sIn.Read(buffer, 0, buffer.Length);                fs.Write(buffer, 0, buffer.Length);                if ((i % 1024) == 0)                {                    j = Math.Round(Convert.ToDecimal((Convert.ToDouble(i) / Convert.ToDouble(length)) * 100), 4);                    t= "当前下载文件大小:" + length.ToString() + "字节   当前下载大小:" + i + "字节 下载进度" + j.ToString() + "%";                }                else                {                   t = "当前下载文件大小:" + length.ToString() + "字节   当前下载大小:" + i + "字节";                }                yield return false;            }            sIn.Close();            wr.Close();            fs.Close();         }    //断点下载    IEnumerator FPointDown(string uri,string saveFile)    {        //打开网络连接         System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(uri);        System.Net.HttpWebRequest requestGetCount = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(uri);        long countLength = requestGetCount.GetResponse().ContentLength;             //打开上次下载的文件或新建文件         long lStartPos = 0;        System.IO.FileStream fs;        if (System.IO.File.Exists(saveFile))        {            fs = System.IO.File.OpenWrite(saveFile);            lStartPos = fs.Length;            if (countLength - lStartPos <= 0)            {                fs.Close();                t = "已经";                yield break;            }            fs.Seek(lStartPos, System.IO.SeekOrigin.Current); //移动文件流中的当前指针         }        else        {            fs = new System.IO.FileStream(saveFile, System.IO.FileMode.Create);        }              if (lStartPos > 0)        {            request.AddRange((int)lStartPos); //设置Range值            print(lStartPos);        }        //向服务器请求，获得服务器回应数据流         System.IO.Stream ns = request.GetResponse().GetResponseStream();        int len = 1024 * 8;                byte[] nbytes = new byte[len];        int nReadSize = 0;        nReadSize = ns.Read(nbytes, 0, len);        while (nReadSize > 0)        {            fs.Write(nbytes, 0, nReadSize);            nReadSize = ns.Read(nbytes, 0, len);            t = "已下载:" + fs.Length / 1024 + "kb /" + countLength / 1024 + "kb";            yield return false;        }        ns.Close();        fs.Close();    }}