安卓通知栏显示文件下载进度

首先创建一个Service ——下载进度

public class DownloadService extends Service {
    
    private DownLoadTask downLoadTask;
    private String downloadUrl;
    private DownloadListener listener =new DownloadListener() {
    
        @Override
        public void onProgress(int progress) {
    
            getNotificationManager().notify(1,getNotification("正在下载软件...",progress));
            Toast.makeText(DownloadService.this, "Download Success", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onSuccess() {
    
            downLoadTask=null;
            //下载成功时将前台服务通知关闭,并且创建一个下载成功的通知
            stopForeground(true);
            getNotificationManager().notify(1,getNotification("Download Success",-1));
            Toast.makeText(DownloadService.this, "Download Success", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onFailed() {
    
            downLoadTask =null;
            //下载失败时将前台服务通知关闭,并创建一个下载失败的通知
            stopForeground(true);
            getNotificationManager().notify(1,getNotification("Download Failed",-1));
            Toast.makeText(DownloadService.this, "Download Failed", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPaused() {
    
            downLoadTask =null;
            Toast.makeText(DownloadService.this, "Paused", Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onCanceled() {
    
            downLoadTask = null;
            stopForeground(true);
            Toast.makeText(DownloadService.this, "Canceled", Toast.LENGTH_SHORT).show();
        }
    };


    private DownloadService.DownloadBinder mBinder =new DownloadService.DownloadBinder();
    private NotificationCompat.Builder builder;

    class DownloadBinder extends Binder {
    
        public void startDownload(String url) {
    

            if (downLoadTask == null) {
    
                downloadUrl = url;
                downLoadTask = new DownLoadTask(listener);
// 在这里开启下载
                downLoadTask.execute(downloadUrl);
// 让这个服务成为一个前台服务。这样就可以在系统状态栏中创建一个持续运行的通知了
                if (Build.VERSION.SDK_INT >=Build.VERSION_CODES.O){
    
                    startForeground(1, getNotification("Downloading...", 0));
                    Toast.makeText(DownloadService.this, "Downing...", Toast.LENGTH_SHORT);
                }
            }
        }



        public void pauseDownload() {
    
            if (downLoadTask != null) {
    
                downLoadTask.pauseDownload();
            }
        }


        public void cancelDownload() {
    
            if (downLoadTask != null) {
    
                downLoadTask.cancleDownload();
            } else {
    
                if (downloadUrl != null) {
    
// 取消下载时需将文件删除，并将通知关闭
                    String fileName = downloadUrl.substring(downloadUrl.lastIndexOf("/"));
                    String directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
                    File file = new File(directory + fileName);
                    if (file.exists()) {
    
                        file.delete();
                    }
                    getNotificationManager().cancel(1);
                    stopForeground(true);
                    Toast.makeText(DownloadService.this, "Cancled", Toast.LENGTH_SHORT).show();
                }
            }
        }
    }


    private NotificationManager getNotificationManager() {
    
        return (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    }


    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
    
        return mBinder;
    }
    private void updateNotification(int progress) {
    
        NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, "default");
        builder.setSmallIcon(R.mipmap.ic_launcher);
        builder.setContentTitle("正在下载...");
        builder.setContentText(progress + "%");
        builder.setProgress(100, progress, false);
        Notification notification = builder.build();
        manager.notify(1, notification);
    }

    private Notification getNotification(String title, int progress) {
    
        Intent intent = new Intent(this, DownloadActivity.class);
        //获得管理
        if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.O) {
    
            NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
            //创建通知渠道
            NotificationChannel channel = new NotificationChannel("myid", "myname", NotificationManager.IMPORTANCE_HIGH);
            manager.createNotificationChannel(channel);
            PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_IMMUTABLE);
            builder = new NotificationCompat.Builder(this,"myid");
            builder.setSmallIcon(R.mipmap.home_kt);
            builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.home_cf));
            builder.setContentTitle(title);
            builder.setContentIntent(pendingIntent);
            builder.setChannelId("myid"); // set notification channel
            builder.setContentTitle("正在下载...");
            builder.setContentText(progress + "%");
            builder.setProgress(100, progress, false);
// builder.notify(1,);

        }
        return builder.build();
    }

}

DownloadActivity——调用

public class DownloadActivity extends AppCompatActivity implements View.OnClickListener {
    
    private DownloadService.DownloadBinder downloadBinder;
    private ServiceConnection connection =new ServiceConnection() {
    
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
    
            downloadBinder = (DownloadService.DownloadBinder) iBinder;
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
    

        }
    };
    @Override @SuppressLint("MissingInflatedId")
    protected void onCreate(Bundle savedInstanceState) {
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_download);
        Button startDownload = findViewById(R.id.start_download);
        Button pause_download = findViewById(R.id.pause_download);
        Button cancel_download = findViewById(R.id.cancel_download);
        startDownload.setOnClickListener(this);
        pause_download.setOnClickListener(this);
        cancel_download.setOnClickListener(this);
        Intent intent =new Intent(this, DownloadService.class);
        //启动服务,不是启动活动Activity
        startService(intent);
        bindService(intent,connection,BIND_AUTO_CREATE);
        if (ContextCompat.checkSelfPermission(DownloadActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)!= PackageManager.PERMISSION_GRANTED){
    
            ActivityCompat.requestPermissions(DownloadActivity.this,new String[]{
    Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
        }
    }

    @Override
    public void onClick(View view) {
    
        if (downloadBinder==null){
    
            return;
        }
        switch (view.getId()){
    
            case R.id.start_download:
                String url = "https://raw.githubusercontent.com/guolindev/eclipse/master/eclipse-inst-win64.exe";
                downloadBinder.startDownload(url);
                break;
            case R.id.pause_download:
                downloadBinder.pauseDownload();
                break;
            case R.id.cancel_download:
                downloadBinder.cancelDownload();
                break;
            default:
                break;
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode){
    
            case  1:
                if (grantResults.length>0 &&grantResults[0]!= PackageManager.PERMISSION_GRANTED){
    
                    Toast.makeText(this,"权限被拒绝了呦",Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
        }

    }

    @Override
    protected void onDestroy() {
    
        super.onDestroy();
        // 要记得解绑，不然可能会造成内存溢出
        unbindService(connection);
    }
}

DownLoadTask ——下载任务

public class DownLoadTask extends AsyncTask<String, Integer, Integer> {
    
    public static final int TYPE_SUCCESS = 0;
    public static final int TYPE_FAIL = 2;
    public static final int TYPE_PAUSED = 3;
    public static final int TYPE_CANCLE = 4;

    private DownloadListener listener;

    private boolean isCanceled = false;
    private boolean isPaused = false;
    private int lastProgress;


    public DownLoadTask(DownloadListener downloadListener) {
    
        listener = downloadListener;
    }

    /** * 在后台任务执行之前调用，用于进行界面上的初始化操作，比如显示一个进度对话框 */
    @Override
    protected void onPreExecute() {
    
        super.onPreExecute();
    }

    /** * 在这里处理所有的耗时任务，任务一旦完成通过return返回 * 这里不能对UI进行操作，因为此处代码都运行在子线程中。 * * @param params * @return */
    @Override
    protected Integer doInBackground(String... params) {
    
        InputStream inputStream = null;
        RandomAccessFile saveFile = null;
        File file = null;
        try {
    
// 记录已下载文件的长度
            long downLoadLenght = 0;
            String downloadUrl = params[0];
            String fileName = downloadUrl.substring(downloadUrl.lastIndexOf("/"));
// SD卡的download目录
            String directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
            file = new File(directory + fileName);
            if (file.exists()) {
    
                downLoadLenght = file.length();
            }
// 获取文件的总长度
            long contentLenght = getContentLenght(downloadUrl);
            if (contentLenght == 0) {
    
                return TYPE_FAIL;
            } else if (contentLenght == downLoadLenght) {
    
// 已下载的字节和文件总字节相等，说明下载已经完成
                return TYPE_SUCCESS;
            }

            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder()
// 断点下载，指定从哪一个节点开始下载
                    .addHeader("RANGE", "bytes=" + downLoadLenght + "-")
                    .url(downloadUrl)
                    .build();
            Response response = client.newCall(request).execute();
            if (response != null) {
    
                inputStream = response.body().byteStream();
                saveFile = new RandomAccessFile(file, "rw");
                saveFile.seek(downLoadLenght);//跳过已下载的字节
            }
            byte[] b = new byte[1024];
            int total = 0;
            int len;
            while ((len = inputStream.read(b)) != -1) {
    
                if (isCanceled) {
    
                    return TYPE_CANCLE;
                } else if (isPaused) {
    
                    return TYPE_PAUSED;
                } else {
    
                    total += len;
                    saveFile.write(b, 0, len);
                    int progress = (int) ((total + downLoadLenght) * 100 / contentLenght);
// 通知进度条更新
                    publishProgress(progress);
                }
            }

            response.body().close();
            return TYPE_SUCCESS;
        } catch (Exception e) {
    
            e.printStackTrace();
        } finally {
    
            try {
    
                if (inputStream != null) {
    
                    inputStream.close();
                }
                if (saveFile != null) {
    
                    saveFile.close();
                }
                if (isCanceled && file != null) {
    
                    file.delete();
                }
            } catch (Exception e) {
    

            }
        }


        return TYPE_FAIL;
    }

    /** * 获取文件的总长度 * @param downloadUrl * @return * @throws IOException */
    private long getContentLenght(String downloadUrl) throws  IOException {
    
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(downloadUrl)
                .build();
        Response response = client.newCall(request).execute();
        if (response != null && response.isSuccessful()) {
    
            long contentLenght = response.body().contentLength();
            response.close();
            return contentLenght;
        }
        return 0;
    }


    /** * 这里可以更新UI了 * * @param values */
    @Override
    protected void onProgressUpdate(Integer... values) {
    
        super.onProgressUpdate(values);
// 从参数中获取到当前的下载进度，和上一次下载进度对比，有变化则通知进度条更新
        int progress = values[0];
        if (progress > lastProgress) {
    
            listener.onProgress(progress);
            lastProgress = progress;
        }

    }

    /** * 但后台任务完成后return后这个方法马上会执行 * 并且rentur的值可以在参数中获得。这里做收尾工作 */
    @Override
    protected void onPostExecute(Integer integer) {
    
        switch (integer) {
    
            case TYPE_CANCLE:
                listener.onCanceled();
                break;
            case TYPE_SUCCESS:
                listener.onSuccess();
                break;
            case TYPE_PAUSED:
                listener.onPaused();
                break;
            case TYPE_FAIL:
                listener.onFailed();
                break;
        }
    }

    public void pauseDownload(){
    
        isPaused =true;
    }

    public void cancleDownload(){
    
        isCanceled =true;
    }

    /** * 执行这个异步任务通过这个异步类的对象.execute() */

}

资源文件权限

<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>