unity3d 关于断点下载和整个下载(用于更新)

using UnityEngine;
using System.Collections;
using System.IO;
using System.Net;
using Math= System.Math;
using Uri = System.Uri;
using Convert= System.Convert;
public class DownloadTest : MonoBehaviour
{

	public UILabel label1;
	public UILabel label2;
	// Use this for initialization
	void Start ()
	{
	
	}
	
	// Update is called once per frame
	void Update ()
	{
	
	}

	void OnGUI ()
	{
		if (GUI.Button (new Rect (0, 0, 100, 20), "Download")) {
			StartCoroutine (downfile ("http://localhost:8888/test.zip", Application.streamingAssetsPath + "/test.zip", label1));
		}
		if (GUI.Button (new Rect (0, 20, 100, 20), "StopDownload")) {
			StopAllCoroutines ();
		}
		if (GUI.Button (new Rect (0, 40, 100, 20), "ResumDownload")) {
			StartCoroutine (FPointDown ("http://localhost:8888/test.zip", Application.streamingAssetsPath + "/test.zip", label2));
		}
	}

	string t = "";
	//整体下载
	IEnumerator downfile (string url, string LocalPath, UILabel DesLable)
	{
		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 () + "%";
				DesLable.text = t.ToString ();
			} else {
				t = "当前下载文件大小:" + length.ToString () + "字节当前下载大小:" + i + "字节";
				DesLable.text = t.ToString ();
			}
			
			yield return false;
			
			
		}
		
		sIn.Close ();
		wr.Close ();
		fs.Close ();
		
	}
	string downloadString = "已经下载";
	//断点下载
	IEnumerator FPointDown (string uri, string saveFile, UILabel DesLable)
	{
		//打开网络连接
		HttpWebRequest request = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create (uri);
		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";
				DesLable.text = t.ToString ();
				yield break;
			}
			fs.Seek (lStartPos, System.IO.SeekOrigin.Current);//移动文件流中的当前指针
		} else {
			fs = new FileStream (saveFile, 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
		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 = downloadString + ":" + fs.Length / 1024 + "kb/" + countLength / 1024 + "kb" + "----" + ((double)fs.Length / countLength).ToString () + "%";
			
			DesLable.text=t;
			yield return false;
		}
		ns.Close ();
		fs.Close ();
		//这里放更新安装代码,或者可以测试这个下载的包有没有出错,验证sha和md5

	} 
}