unity-多线程异步下载HttpWebRequest

unity-多线程异步下载HttpWebRequest

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前篇

• 官方 - https://docs.microsoft.com/zh-cn/dotnet/framework/network-programming/making-asynchronous-requests

使用的是 .net 里面的网络库 HttpWebRequest, 应用场景是需要同时下载多个小文件时, 效果很明显, 例如: 散文件热更.

效果如下, 最终下载完大小是 31,715KB

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代码

• csharp 代码, 里面包含 unity 和 tolua 相关, 自行去掉即可

  using System;
  using System.Collections;
  using System.Collections.Generic;
  using System.IO;
  using System.Net;
  using System.Text;
  using LuaInterface;
  using UnityEngine;
  
  public enum EMDErr : int {
      CreateRequest = -10001,
      GetResponse = -10002,
      NullResponse = -10003,
      ReadStream = -10004,
  }
  
  public class MultiDownObj {
      public string url;
      public string path;
      public LuaFunction luaFn;
  
      // 透传参数
      [NoToLua]
      public bool isDone = false;
      [NoToLua]
      public int code;
      [NoToLua]
      public HttpWebRequest httpReq;
      [NoToLua]
      public HttpWebResponse httpRsp;
      [NoToLua]
      public byte[] buffer;
      [NoToLua]
      public Stream rspStream;
      [NoToLua]
      public FileStream fs;
  }
  
  // 多线程异步下载
  public class MultiDownMgr : MonoBehaviour {
      private static MultiDownMgr _instance;
      public static MultiDownMgr Instance {
          get { return _instance; }
      }
  
      private const int BufferSize = 1024;
  
      private AsyncCallback rspCb = null;
      private AsyncCallback readCb = null;
  
      private List<MultiDownObj> objList = new List<MultiDownObj>();
  
      public int timeout = 10000; // 10s 超时
      public bool keepAlive = true;
      public int connectLimit {
          set { ServicePointManager.DefaultConnectionLimit = value; } // 并发线程数量
      }
  
      void Awake() {
          _instance = this;
  
          rspCb = new AsyncCallback(ResponseCb);
          readCb = new AsyncCallback(ReadDataCb);
  
          connectLimit = 32; // 默认 32 个并发
      }
  
      // lua 接口
      public void Request(string url, string path, LuaFunction fn) {
          // LogUtil.D("--- Request, url: {0}, path: {1}", url, path);
          MultiDownObj mdObj = new MultiDownObj();
          mdObj.url = url;
          mdObj.path = path;
          mdObj.luaFn = fn;
          RequestObj(mdObj);
      }
  
      void RequestObj(MultiDownObj mdObj) {
          objList.Add(mdObj);
          try {
              mdObj.httpReq = WebRequest.Create(mdObj.url) as HttpWebRequest;
              mdObj.httpReq.Method = "GET";
              mdObj.httpReq.Timeout = timeout;
              mdObj.httpReq.KeepAlive = keepAlive; // 设置为 false 会导致中断下载, 报错: Remote prematurely closed connection.
              mdObj.httpReq.BeginGetResponse(rspCb, mdObj);
          } catch (System.Exception ex) {
              Close(mdObj);
              mdObj.code = (int) EMDErr.CreateRequest;
              mdObj.path = ex.Message;
              mdObj.isDone = true;
          }
      }
  
      void ResponseCb(IAsyncResult ar) {
          MultiDownObj mdObj = ar.AsyncState as MultiDownObj;
          try {
              HttpWebResponse response = mdObj.httpReq.EndGetResponse(ar) as HttpWebResponse;
              if (response == null) {
                  Close(mdObj);
                  mdObj.code = (int) EMDErr.NullResponse;
                  mdObj.isDone = true;
                  return;
              }
  
              mdObj.httpRsp = response;
              mdObj.code = (int) response.StatusCode;
              mdObj.rspStream = response.GetResponseStream();
              if (response.StatusCode != HttpStatusCode.OK) {
                  Close(mdObj);
                  mdObj.isDone = true;
                  return;
              }
  
              // 创建父目录
              string dirPath = System.IO.Path.GetDirectoryName(mdObj.path);
              if (!Utils.IsDirectoryExist(dirPath)) {
                  Utils.CreateDirectory(dirPath);
              }
  
              mdObj.fs = new FileStream(mdObj.path, FileMode.Create);
              mdObj.buffer = new byte[BufferSize];
              mdObj.rspStream.BeginRead(mdObj.buffer, 0, BufferSize, readCb, mdObj);
          } catch (System.Exception ex) {
              Close(mdObj);
              mdObj.code = (int) EMDErr.GetResponse;
              mdObj.path = ex.Message;
              mdObj.isDone = true;
          }
      }
  
      void ReadDataCb(IAsyncResult ar) {
          MultiDownObj mdObj = ar.AsyncState as MultiDownObj;
          try {
              int read = mdObj.rspStream.EndRead(ar);
              if (read > 0) {
                  mdObj.fs.Write(mdObj.buffer, 0, read);
                  mdObj.fs.Flush();
                  mdObj.rspStream.BeginRead(mdObj.buffer, 0, BufferSize, readCb, mdObj);
              } else {
                  Close(mdObj);
                  mdObj.isDone = true;
              }
          } catch (System.Exception ex) {
              Close(mdObj);
              mdObj.code = (int) EMDErr.ReadStream;
              mdObj.path = ex.Message;
              mdObj.isDone = true;
              return;
          }
  
      }
  
      // 释放资源
      void Close(MultiDownObj mdObj) {
          if (mdObj == null)
              return;
  
          if (mdObj.fs != null) {
              mdObj.fs.Close();
              mdObj.fs = null;
          }
  
          if (mdObj.rspStream != null) {
              mdObj.rspStream.Close();
              mdObj.rspStream = null;
          }
  
          if (mdObj.httpRsp != null) {
              mdObj.httpRsp.Close();
              mdObj.httpRsp = null;
          }
  
          if (mdObj.httpReq != null) {
              mdObj.httpReq.Abort();
              mdObj.httpReq = null;
          }
  
          mdObj.buffer = null;
      }
  
      public void StopDown(string url) {
          for (int i = 0; i < objList.Count; ++i) {
              if (objList[i].url == url) {
                  objList.RemoveAt(i);
                  i -= 1;
              }
          }
      }
  
      public void StopAll() {
          objList.Clear();
      }
  
      private void Update() {
          for (int i = 0; i < objList.Count; ++i) {
              MultiDownObj mdObj = objList[i];
              if (mdObj.isDone) {
                  // LogUtil.D("--- mdObj done, code: {0}, path: {1}", mdObj.code, mdObj.path);
                  if (mdObj.luaFn != null) {
                      mdObj.luaFn.Call(mdObj.code, mdObj.url, mdObj.path);
                      mdObj.luaFn.Dispose();
                      mdObj.luaFn = null;
                  }
  
                  objList.RemoveAt(i);
                  i -= 1;
              }
          }
      }
  }

• lua 测试代码

  function gDebugCustom.MultiDown()
      local function downFn(code, url, path)
          gLog("--- code: {0}, url: {1}, path: {2}", code, url, path)
      end
  
      for i=1,5 do
          local url = "https://www.aaa.com/download/game.apk"
          local path = gTool.PathJoin(Application.persistentDataPath, string.formatExt("apks/aaa-{0}.apk", i))
          MultiDownMgr.Instance:Request(url, path, downFn);
      end
  end

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