新答案(Unity 2017.2及更高版本)
Use UnityWebRequest with DownloadHandlerFile. The DownloadHandlerFile
类是新的,用于直接下载和保存文件,同时防止高内存使用。
IEnumerator Start()
{
string url = "http://dl3.webmfiles.org/big-buck-bunny_trailer.webm";
string vidSavePath = Path.Combine(Application.persistentDataPath, "Videos");
vidSavePath = Path.Combine(vidSavePath, "MyVideo.webm");
//Create Directory if it does not exist
if (!Directory.Exists(Path.GetDirectoryName(vidSavePath)))
{
Directory.CreateDirectory(Path.GetDirectoryName(vidSavePath));
}
var uwr = new UnityWebRequest(url);
uwr.method = UnityWebRequest.kHttpVerbGET;
var dh = new DownloadHandlerFile(vidSavePath);
dh.removeFileOnAbort = true;
uwr.downloadHandler = dh;
yield return uwr.SendWebRequest();
if (uwr.isNetworkError || uwr.isHttpError)
Debug.Log(uwr.error);
else
Debug.Log("Download saved to: " + vidSavePath.Replace("/", "\\") + "\r\n" + uwr.error);
}
旧答案(Unity 2017.1 及以下版本)如果您想在下载文件时访问每个字节,请使用)
像这样的问题就是 Unity 的原因UnityWebRequest已制作但无法直接使用,因为WWW
API 现在是在UnityWebRequest
最新版本的 Unity 中的 API 这意味着如果您遇到错误WWW
API,您也可能会遇到同样的错误UnityWebRequest
。即使它有效,您也可能会在 Android 等具有小内存的移动设备上遇到问题。
要做的就是使用 UnityWebRequestDownloadHandlerScript允许您分块下载数据的功能。通过分块下载数据,可以防止导致溢出错误。这WWW
API没有实现这个功能所以UnityWebRequest
and DownloadHandlerScript
必须用于分块下载数据。您可以阅读这是如何工作的here.
虽然这应该可以解决您当前的问题,但在尝试使用以下命令保存大量数据时,您可能会遇到另一个内存问题File.WriteAllBytes
. Use FileStream
执行保存部分并仅在下载完成后关闭它。
创建自定义UnityWebRequest
用于按块下载数据,如下所示:
using System;
using System.IO;
using UnityEngine;
using UnityEngine.Networking;
public class CustomWebRequest : DownloadHandlerScript
{
// Standard scripted download handler - will allocate memory on each ReceiveData callback
public CustomWebRequest()
: base()
{
}
// Pre-allocated scripted download handler
// Will reuse the supplied byte array to deliver data.
// Eliminates memory allocation.
public CustomWebRequest(byte[] buffer)
: base(buffer)
{
Init();
}
// Required by DownloadHandler base class. Called when you address the 'bytes' property.
protected override byte[] GetData() { return null; }
// Called once per frame when data has been received from the network.
protected override bool ReceiveData(byte[] byteFromServer, int dataLength)
{
if (byteFromServer == null || byteFromServer.Length < 1)
{
Debug.Log("CustomWebRequest :: ReceiveData - received a null/empty buffer");
return false;
}
//Write the current data chunk to file
AppendFile(byteFromServer, dataLength);
return true;
}
//Where to save the video file
string vidSavePath;
//The FileStream to save the file
FileStream fileStream = null;
//Used to determine if there was an error while opening or saving the file
bool success;
void Init()
{
vidSavePath = Path.Combine(Application.persistentDataPath, "Videos");
vidSavePath = Path.Combine(vidSavePath, "MyVideo.webm");
//Create Directory if it does not exist
if (!Directory.Exists(Path.GetDirectoryName(vidSavePath)))
{
Directory.CreateDirectory(Path.GetDirectoryName(vidSavePath));
}
try
{
//Open the current file to write to
fileStream = new FileStream(vidSavePath, FileMode.OpenOrCreate, FileAccess.ReadWrite);
Debug.Log("File Successfully opened at" + vidSavePath.Replace("/", "\\"));
success = true;
}
catch (Exception e)
{
success = false;
Debug.LogError("Failed to Open File at Dir: " + vidSavePath.Replace("/", "\\") + "\r\n" + e.Message);
}
}
void AppendFile(byte[] buffer, int length)
{
if (success)
{
try
{
//Write the current data to the file
fileStream.Write(buffer, 0, length);
Debug.Log("Written data chunk to: " + vidSavePath.Replace("/", "\\"));
}
catch (Exception e)
{
success = false;
}
}
}
// Called when all data has been received from the server and delivered via ReceiveData
protected override void CompleteContent()
{
if (success)
Debug.Log("Done! Saved File to: " + vidSavePath.Replace("/", "\\"));
else
Debug.LogError("Failed to Save File to: " + vidSavePath.Replace("/", "\\"));
//Close filestream
fileStream.Close();
}
// Called when a Content-Length header is received from the server.
protected override void ReceiveContentLength(int contentLength)
{
//Debug.Log(string.Format("CustomWebRequest :: ReceiveContentLength - length {0}", contentLength));
}
}
如何使用:
UnityWebRequest webRequest;
//Pre-allocate memory so that this is not done each time data is received
byte[] bytes = new byte[2000];
IEnumerator Start()
{
string url = "http://dl3.webmfiles.org/big-buck-bunny_trailer.webm";
webRequest = new UnityWebRequest(url);
webRequest.downloadHandler = new CustomWebRequest(bytes);
webRequest.SendWebRequest();
yield return webRequest;
}