发布：2021/10/26 8:51:55作者：管理员 来源：本站 浏览次数：982

前言

最近需要做一个android的app。但是我不会java呀，虽然大学时候学过，但是完全还给老师了。于是我就用C#做了一个Android的app。如果有问题请QQ联系1067097173
环境准备

vs2019 iis .netcore3.0 xamarin

iis用来存放发布的apk，最终可以通过http访问下载相关文件 update存放版本号

具体实现

在app程序启动方法中检查当前的版本，然后下载服务器存放的update.txt来对比，然后把apk下载到手机本地，最后更新。
具体代码

    public string GetVersion(string url)
            {
                try
                {
                    WebClient client = new WebClient();
                    Stream str = client.OpenRead(url);
                    StreamReader reader = new StreamReader(str);
                    var value = reader.ReadLine();
                    return value;
                }
                catch (System.Exception exp)
                {
                    Toast.MakeText(this, "更新异常:" + exp.Message, ToastLength.Long).Show();
                    return "";
                }
            }
     
            [Obsolete]
            public void DownFile(string url)
            {
     
                //loading = new AlertDialog.Builder(this);
                //loading.SetTitle("下载文件");
                //loading.SetMessage("更新中...");
                //alertDialog = loading.Show();
                //progressDialogHandler = new Handler((w) =>
                //{
                //    loading.SetMessage(w.Obj.ToString());
                //    Toast.MakeText(loading.Context, w.Obj.ToString(), ToastLength.Short).Show();
                //});
                pg = new ProgressDialog(this);
                pg.SetTitle ("文件下载中...");
                pg.Max = 100;
                pg.SetCancelable(false);
                pg.SetProgressStyle(ProgressDialogStyle.Horizontal);
                pg.Show();
     
     
                try
                {
                    //if (Android.OS.Environment.ExternalStorageState.Equals(Android.OS.Environment.MediaMounted))
                    //{
                    WebClient client = new WebClient();
                    client.DownloadFileCompleted += client_DownloadFileCompleted;
                    client.DownloadProgressChanged += client_DownloadProgressChanged;
                    var backingFile = System.IO.Path.Combine(Xamarin.Essentials.FileSystem.AppDataDirectory, "count.txt");
                    var saveFolder = Android.OS.Environment.ExternalStorageDirectory;
                    //var saveFolder = Android.OS.Environment.DataDirectory;
                    //if (!Android.OS.fie System.IO.Directory.Exists(saveFolder)) System.IO.Directory.CreateDirectory(saveFolder);
                    var file = string.Format("{0}/{1}{2}", saveFolder, this.PackageName, ".apk");// fileName + "appName" + versionName + ext;
                    file = string.Format("{0}/{1}{2}", Xamarin.Essentials.FileSystem.AppDataDirectory, this.PackageName, ".apk");
                    if (System.IO.Directory.Exists(Xamarin.Essentials.FileSystem.AppDataDirectory)) {
                    
                    }
                    using (var fs = new FileStream(file, FileMode.Create))
                    {
     
                    }
     
                    client.DownloadFileAsync(new Uri(url), file);
     
                    //}
                }
                catch (System.Exception exp)
                {
                    Toast.MakeText(this, "更新异常:" + exp.Message, ToastLength.Long).Show();
                    ;
                }
            }
            private void OpenUpDialog(string sourcever, string updatever)
            {
                builder = new AlertDialog.Builder(this);
                builder.SetTitle("有新版本!!!").SetMessage(string.Format("当前:{0}    新版本:{1}", sourcever, updatever)).SetNeutralButton("暂不更新",
               (s, e) => {
                   var UserNO = ReadData2("UserNO");
                   var Userid = ReadData2("Userid");
                   var password = ReadData2("Password");
                   var username = ReadData2("UserName");
                   if (JudgeLoginFunction(UserNO, password))
                   {
                       Intent intent = new Intent(this, typeof(WebTestActivity));
                       intent.PutExtra("UserNO", UserNO);
                       intent.PutExtra("Userid", Userid);
                       intent.PutExtra("UserName", username);
                       StartActivity(intent);
                   }
     
               }).SetPositiveButton("立即更新", (s, e) =>
               {
                   DownFile(pathdir + "/" + this.PackageName + ".apk");
     
               }).Show();
     
            }
            void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
            {
                if (e.UserState == null)
                {
     
                    //this.lblMessage.Text = e.UserState.ToString() + ",下载完成";
                    Intent i = new Intent(Intent.ActionView);
                    var saveFolder = Android.OS.Environment.ExternalStorageDirectory;
                    //if (!Android.OS.fie System.IO.Directory.Exists(saveFolder)) System.IO.Directory.CreateDirectory(saveFolder);
                    var file = string.Format("{0}/{1}{2}", saveFolder, this.PackageName, ".apk");// fileName + "appName" +
                    //i.SetDataAndType(Android.Net.Uri.FromFile(new Java.IO.File(file)), "application/vnd.android.package-archive");
                    //i.SetFlags(ActivityFlags.NewTask);
                    file = string.Format("{0}/{1}{2}", Xamarin.Essentials.FileSystem.AppDataDirectory, this.PackageName, ".apk");
                    //StartActivity(i);
                    Java.IO.File apkFile = new Java.IO.File(file);
     
                    Intent intent = new Intent(Intent.ActionView);
                    intent.SetFlags(ActivityFlags.NewTask);
                    if (Build.VERSION.SdkInt >= BuildVersionCodes.N)
                    {
                        intent.SetFlags(ActivityFlags.GrantReadUriPermission);
                        Android.Net.Uri uri = FileProvider.GetUriForFile(this, PackageName + ".fileprovider", apkFile);
                        intent.SetDataAndType(uri, "application/vnd.android.package-archive");
                    }
                    else
                    {
                        intent.SetDataAndType(Android.Net.Uri.FromFile(new Java.IO.File(file)), "application/vnd.android.package-archive");
                    }
                    StartActivity(intent);
     
                }
                if (e.Error != null)
                {
                    Toast.MakeText(this, "更新异常:" + e.Error.Message, ToastLength.Long).Show();
                }
                pg.Dismiss();
            }
     
            void client_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
            {
                //this.proBarDownLoad.Minimum = 0;
                //this.proBarDownLoad.Maximum = (int)e.TotalBytesToReceive;
                //this.proBarDownLoad.Value = (int)e.BytesReceived;
                //this.lblPercent.Text = e.ProgressPercentage + "%";
                //pg.Max = (int)e.TotalBytesToReceive;
                pg.Progress = e.ProgressPercentage;
                //progressDialogHandler.SendMessage(new Message() { Obj= "更新中..."+ e.ProgressPercentage + "%" });
     
     
            }

注意问题

    1 iis部署时候 MIME类型一定要设置为”application/vnd.android.package-archive“，不然当手机下载完成后不会自动提示安装

    2 由于android版本权限控制问题，下载存放的地方最好不要放的外部存储，会报权限不足，
    3 高版本的android需要用fileprovider方式安装