鄭重聲明：轉載請注明出處 U_探索

本文誕生于樂元素面試過程，被面試官問到AssetBundle多線程異步下載時，愣了半天，同樣也被深深的鄙視一回（做了3年多u3d 這個都沒用過），所以發誓要實現出來填補一下自己的空白，同時分享給大家。說明：本人只在pc和Android下測試好使，其他平臺未知！

直接貼代碼，都是C# http的API，不懂得自己百科。

using UnityEngine;
using System.Collections;
using System;
using System.Text;
using System.Net;
using System.IO;internal class WebReqState
{public byte[] Buffer;public FileStream fs;public const int BufferSize = 1024;public Stream OrginalStream;public HttpWebResponse WebResponse;public WebReqState(string path){Buffer = new byte[1024];fs = new FileStream(path,FileMode.Create);}}public class HttpHelper {string path = null;string assetName;public HttpHelper(string path){this.path = path;}public  void AsyDownLoad(string url)
{Debug.Log(url);assetName = url.Split('/')[4];Debug.Log(assetName);HttpWebRequest httpRequest = WebRequest.Create(url) as HttpWebRequest;httpRequest.BeginGetResponse( new AsyncCallback(ResponseCallback), httpRequest);
}void ResponseCallback(IAsyncResult ar)
{HttpWebRequest req = ar.AsyncState as HttpWebRequest;if(req == null) return;HttpWebResponse response = req.EndGetResponse(ar) as HttpWebResponse;if(response.StatusCode != HttpStatusCode.OK){response.Close();return;}Debug.Log(path+ "/"+assetName);WebReqState st = new WebReqState(path+ "/"+assetName);st.WebResponse = response;Stream responseStream = response.GetResponseStream();st.OrginalStream = responseStream;responseStream.BeginRead(st.Buffer,0,WebReqState.BufferSize,new AsyncCallback(ReadDataCallback),st);
}void ReadDataCallback(IAsyncResult ar)
{WebReqState rs = ar.AsyncState as WebReqState;int read =rs.OrginalStream.EndRead(ar);if(read>0){rs.fs.Write(rs.Buffer,0,read);rs.fs.Flush();rs.OrginalStream.BeginRead(rs.Buffer, 0, WebReqState.BufferSize, new AsyncCallback(ReadDataCallback), rs);}else{rs.fs.Close();rs.OrginalStream.Close();rs.WebResponse.Close();Debug.Log(assetName+":::: success");}
}
}

View Code

下載部分：

if(GUI.Button(new Rect(0,0,100,30),"test"))
{string rootPath = Application.persistentDataPath;//android上保存到 /storage/sdcard0/Android/data/包名(例如：com.example.test)/filesfor(int i =0;i<str.Length;i++) //str是string型數組，存放部分assetbundle名字
    {Thread thread = new Thread(new ParameterizedThreadStart(DownAsset)); //ParameterizedThreadStart 多線程傳參 thread.Start(rootPath+"|"+str[i]); //只能帶一個object參數 所以使用字符串拼接
    }
} void DownAsset(System.Object file)
{string[] fileName = file.ToString().Split('|');HttpHelper help = new HttpHelper(fileName[0]);help.AsyDownLoad("http://192.168.0.103/unity/"+fileName[1]+".AssetBundle");//注意在手機上測試 該對Ip地址
}

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下載完成后 可以去/storage/sdcard0/Android/data/包名(例如：com.example.test)/files查找對應文件

加載部分：

if(GUI.Button(new Rect(0,30,100,30),"load"))
{for(int i =0;i<str.Length;i++){StartCoroutine(LoadAsset(str[i],i));}
}
IEnumerator LoadAsset(string name,int i)
{WWW w = new WWW("file://"+Application.persistentDataPath+"/"+name+".AssetBundle");yield return w;Instantiate(w.assetBundle.mainAsset,new Vector3(i*2,0,0),Quaternion.identity);w.assetBundle.Unload(false);
}

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注意事項：

1、pc測試 需要修改IP地址，本地測試改為127.0.0.1 同時Application.persistentDataPath最好做修改，因為在pc上Application.persistentDataPath：C:\Users\用戶名\AppData\LocalLow\DefaultCompany\u3d工程名，可以下載到此文件夾下，但是加載的時候會報錯，沒什么權限之類的

2、android上需要stripping level設置為Disabled

轉載于:https://www.cnblogs.com/U-tansuo/p/unity3d_Threading_AsyDown_HTTP.html

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