Android開發 DownloadManager詳解

前言

　　DownloadManager是Android系統自帶的下載管理工具，此工具可以很好的調度好下載。在沒有特殊需求的情況下，一般是推薦使用此工具下載的。另外這個工具下載還有有優勢就是可以在下載app完成后直接跳轉到安裝頁面。

　　參考：https://www.jianshu.com/p/e0496200769c

需要的權限

需要網絡權限和文件讀寫權限

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

創建下載請求

    private void down(){
        DownloadManager downloadManager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
        DownloadManager.Request request = new DownloadManager.Request(Uri.parse("https://dl.hdslb.com/mobile/latest/iBiliPlayer-html5_app_bili.apk"));//添加下載文件的網絡路徑
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "iBiliPlayer-html5_app_bili.apk");//添加保存文件路徑與名稱
        request.setTitle("測試下載");//添加在通知欄里顯示的標題
        request.setDescription("下載中");//添加在通知欄里顯示的描述
        request.addRequestHeader("token","11");//如果你的下載需要token，或者有秘鑰要求，可以在此處添加header的 key： value
        request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);//設置下載的網絡類型
        request.setVisibleInDownloadsUi(false);//是否顯示下載 從Android Q開始會被忽略
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);//下載中與下載完成后都會在通知中顯示| 另外可以選 DownloadManager.Request.VISIBILITY_VISIBLE 僅在下載中時顯示在通知中,完成后會自動隱藏
        long id = downloadManager.enqueue(request);//加入隊列，會返回一個唯一下載id
    }

 

加入列隊后，下載就進行了。我們可以在下拉通知欄里看到正在下載的文件。

另外注意 setDestinationInExternalPublicDir方法已經包含根目錄路徑了，所以直接傳入DIRECTORY_DOWNLOADS就可以了，千萬不要在導入一個 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getPath() 這樣他會自動在創建多層目錄

 

查詢即將保存的下載文件路徑與文件名稱

private void queryFileName(long id){
        DownloadManager downloadManager = (DownloadManager) MainActivity.this.getApplication().getSystemService(Context.DOWNLOAD_SERVICE);
        DownloadManager.Query query = new DownloadManager.Query();
        query.setFilterById(id);
        Cursor cursor = downloadManager.query(query);
        if (cursor.moveToFirst()) {
            String file = cursor.getString(cursor.getColumnIndexOrThrow(DownloadManager.COLUMN_LOCAL_URI));
            Log.e("調試_臨時_log", "this_" + file);
        }
    }

監聽下載狀態

                AppDownReceiver appDownReceiver = new AppDownReceiver();
                registerReceiver(appDownReceiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));

 廣播部分代碼

public class DownloadReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (!TextUtils.equals(action, DownloadManager.ACTION_DOWNLOAD_COMPLETE)){
            return;
        }
        long downloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
        if (downloadId == -1){
            return;
        }
        DownloadManager downloadManager = (DownloadManager) context.getApplicationContext().getSystemService(Context.DOWNLOAD_SERVICE);
        int status = getDownloadStatus(downloadManager, downloadId);
        if (status != DownloadManager.STATUS_SUCCESSFUL){ //下載狀態不等於成功就跳出
            return;
        }
        Uri uri = downloadManager.getUriForDownloadedFile(downloadId);//獲取下載完成文件uri
        if (uri == null){
            return;
        }
    }
/**
     * 獲取下載狀態
     * @param downloadManager
     * @param downloadId
     * @return
     */
    private int getDownloadStatus(DownloadManager downloadManager, long downloadId) {
        DownloadManager.Query query = new DownloadManager.Query().setFilterById(downloadId);
        Cursor c = downloadManager.query(query);
        if (c != null) {
            try {
                if (c.moveToFirst()) {
                    return c.getInt(c.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS));
                }
            } finally {
                c.close();
            }
        }
        return -1;
    }


}

下載狀態查詢

    /**
     * 獲取下載狀態
     *
     * @param downloadId an ID for the download, unique across the system.
     *                   This ID is used to make future calls related to this download.
     * @return int
     * @see DownloadManager#STATUS_PENDING  　　 下載等待開始時
     * @see DownloadManager#STATUS_PAUSED   　　 下載暫停
     * @see DownloadManager#STATUS_RUNNING　     正在下載中　
     * @see DownloadManager#STATUS_SUCCESSFUL   下載成功
     * @see DownloadManager#STATUS_FAILED       下載失敗
     */
    public int getDownloadStatus(long downloadId) {
        DownloadManager.Query query = new DownloadManager.Query().setFilterById(downloadId);
        Cursor c = downloadManager.query(query);
        if (c != null) {
            try {
                if (c.moveToFirst()) {
                    return c.getInt(c.getColumnIndexOrThrow(DownloadManager.COLUMN_STATUS));
                }
            } finally {
                c.close();
            }
        }
        return -1;
    }

下載進度查詢

  /**
     * 獲取當前下載進度
     *
     * @return
     */
    private int getDownloadProgress() {
        DownloadManager.Query query = new DownloadManager.Query().setFilterById(mDownloadId);
        Cursor c = mDownloadManager.query(query);
        if (c != null) {
            try {
                if (c.moveToFirst()) {
                    return c.getInt(c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
                }
            } finally {
                c.close();
            }
        }
        return -1;

    }

    /**
     * 獲取下載總大小
     *
     * @return
     */
    private int getDownloadTotal() {
        DownloadManager.Query query = new DownloadManager.Query().setFilterById(mDownloadId);
        Cursor c = mDownloadManager.query(query);
        if (c != null) {
            try {
                if (c.moveToFirst()) {
                    return c.getInt(c.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES));
                }
            } finally {
                c.close();
            }
        }
        return -1;
    }

安裝下載完成的App

    /**
     * 安裝apk
     */
    private void installApk(long id) {
        Uri uri = mDownloadManager.getUriForDownloadedFile(id);
        Intent install = new Intent(Intent.ACTION_VIEW);
        install.setDataAndType(uri, "application/vnd.android.package-archive");
        install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_GRANT_READ_URI_PERMISSION);
        getApplication().startActivity(install);

    }

 

 

 

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