Unity loads AssetBundle resources from the server and writes them to local memory, and loads the downloaded and saved AB resources from local memory to the scene

Load resources from the server ：

AB After the resource is packaged, there is a 【 Directory file 】AssetBundle, He kept all AB The path and name of the resource ,

adopt aLLAssetBundleURL Link path Assembly from 【 Directory file 】 To obtain the AB The name of the resource , Then write the relevant code in the coordination method , So as to realize the function of loading resources from the server . See the code for details .

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;
using System.IO;

public class DownLoadAssetBundle : MonoBehaviour
{
    //AB Where the resource file is saved in the server ( My server sent , Unable to load )
    private string mainAssetBundleURL = @"http://120.24.90.173/Luademo/AssetBundles/AssetBundles";
    private string aLLAssetBundleURL = @"http://120.24.90.173/Luademo/AssetBundles/";
    
    void Start()
    {
        StartCoroutine("DownLoadMainAssetBundle");
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            LoadAssetBundle();
        }
    }
    
    /// <summary>
    ///  Download master [ Catalog ]AssetBundle file 
    /// </summary>
    IEnumerator DownLoadMainAssetBundle()
    {
        // Create a get  AssetBundle  Of documents  web  request .
        UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(mainAssetBundleURL);

        // Send this  web  request .
        yield return request.SendWebRequest();

        // from  web  Get content from request , Will return a  AssetBundle  Data of type .
        AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);

        if (ab == null)
        {
            Debug.Log("not ab");
        }

        // From this “ Directory file  AssetBundle” In order to get  manifest  data .
        AssetBundleManifest manifest = ab.LoadAsset<AssetBundleManifest>("AssetBundleManifest");

        // Access to this  manifest  All of the  AssetBundle  Name information of .
        string[] names = manifest.GetAllAssetBundles();
        for (int i = 0; i < names.Length; i++)
        {
            // Group spell out the download path link .
            Debug.Log(aLLAssetBundleURL + names[i]);

            // Download single AssetBundle Load the file into the scene .
            //StartCoroutine(DownLoadSingleAssetBundle(aLLAssetBundleURL + names[i]));
            
            // download AssetBundle And save to local .
            StartCoroutine(DownLoadAssetBundleAndSave(aLLAssetBundleURL + names[i]));
        }

    }

    /// <summary>
    ///  Download single AssetBundle Load the file into the scene 
    /// </summary>
    IEnumerator DownLoadSingleAssetBundle(string url)
    {
        UnityWebRequest request = UnityWebRequestAssetBundle.GetAssetBundle(url);
        yield return request.SendWebRequest();
        AssetBundle ab = DownloadHandlerAssetBundle.GetContent(request);

        // By getting  AssetBundle  Object to get the names of all internal resources ( route ), Returns an array .
        string[] names = ab.GetAllAssetNames();
        for (int i = 0; i < names.Length; i++)
        {
            //Debug.Log(names[i]);

            // Intercept the file name in the path address , And no suffix .  Need to introduce  System.IO  Namespace .
            string tempName = Path.GetFileNameWithoutExtension(names[i]);
            Debug.Log(tempName);

            // Instantiation .
            GameObject obj = ab.LoadAsset<GameObject>(tempName);
            GameObject.Instantiate<GameObject>(obj);
        }
    }

    /// <summary>
    ///  download AssetBundle And save to local 
    /// </summary>
    IEnumerator DownLoadAssetBundleAndSave(string url)
    {
        //UnityWebRequestAssetBundle.GetAssetBundle(string uri) Use this API The downloaded resource does not support original data access .
        UnityWebRequest request = UnityWebRequest.Get(url);
        yield return request.SendWebRequest();

        // Indicates whether the download status is complete .
        if (request.isDone)
        {
            // Use  IO  Technology puts this  request  Objects are stored locally .( Suffix required )
            //SaveAssetBundle(Path.GetFileName(url), request.downloadHandler.data, request.downloadHandler.data.Length);
            SaveAssetBundle2(Path.GetFileName(url), request);
        }
    }

    /// <summary>
    ///  Method 1
    ///  Storage AssetBundle For local files 
    /// </summary>
    private void SaveAssetBundle(string fileName, byte[] bytes, int count)
    {
        // Create a file information object .
        FileInfo fileInfo = new FileInfo(Application.streamingAssetsPath + "//" + fileName);

        // Through the file information object “ establish ” Method , Get a file stream object .
        FileStream fs = fileInfo.Create();

        // Through file stream objects , Write information to this file .
        //fs.Write( Byte array ,  Starting position ,  Data length );
        fs.Write(bytes, 0, count);

        // The file is written and stored on the hard disk , Close the file stream object , Destroy the object of the document .
        fs.Flush();
        fs.Close();
        fs.Dispose();

        Debug.Log(fileName + " The download ");
    }

    /// <summary>
    ///  Method 2
    ///  Storage AssetBundle For local files 
    /// </summary>
    private void SaveAssetBundle2(string fileName, UnityWebRequest request)
    {
        // Construct file stream .
        FileStream fs = File.Create(Application.streamingAssetsPath + "//" + fileName);

        // Write byte stream to file ,request.downloadHandler.data You can get the byte stream of the download resource .
        fs.Write(request.downloadHandler.data, 0, request.downloadHandler.data.Length);

        // The file is written and stored on the hard disk , Close the file stream object , Destroy the object of the document .
        fs.Flush();
        fs.Close();
        fs.Dispose();

        Debug.Log(fileName + " The download ");
    }

    /// <summary>
    ///  Load from local  AB  Resources and instantiate 
    /// </summary>
    private void LoadAssetBundle()
    {
        // Load from local  AB  Resources to memory .
        AssetBundle assetBundle = AssetBundle.LoadFromFile(Application.streamingAssetsPath + "/player1.ab");

        // from  AB  Get resources from resources .
        GameObject player = assetBundle.LoadAsset<GameObject>("Necromancer");

        GameObject.Instantiate<GameObject>(player, Vector3.zero, Quaternion.identity);
    }
}