PackageDownloadTest.cs

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

public class PackageDownloadTest : EditorWindow
{

	[MenuItem("Window/PackageDownloadTest")]
	static void Open()
	{
		GetWindow<PackageDownloadTest>();
	}

	string downloadURL;

	private void OnGUI()
	{
		downloadURL = EditorGUILayout.TextField(downloadURL);
		if (GUILayout.Button("Download"))
		{
			var request = UnityWebRequest.Get(downloadURL);
			request.SendWebRequest();
			while (!request.isDone && !request.isNetworkError && !request.isHttpError)
			{
				if (EditorUtility.DisplayCancelableProgressBar("downloading", "downloading package...", request.downloadProgress))
				{
					request.Abort();
					break;
				}

				Thread.Sleep(1);
			}

			if (!string.IsNullOrEmpty(request.error))
			{
				throw new System.Exception(request.error);
			}

			var tempFilePath = Path.GetTempFileName();
			File.WriteAllBytes(tempFilePath, request.downloadHandler.data);

			AssetDatabase.ImportPackage(tempFilePath, false);
		}
	}
}