Android开发 DownloadManager详解

前言

　　DownloadManager是Android系统自带的下载管理工具，此工具可以很好的调度好下载。在没有特殊需求的情况下，一般是推荐使用此工具下载的。另外这个工具下载还有有优势就是可以在下载app完成后直接跳转到安装页面。

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

需要的权限

需要网络权限和文件读写权限

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

创建下载请求

    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"));//添加下载文件的网络路径
        request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "iBiliPlayer-html5_app_bili.apk");//添加保存文件路径与名称
        request.setTitle("测试下载");//添加在通知栏里显示的标题
        request.setDescription("下载中");//添加在通知栏里显示的描述
        request.addRequestHeader("token","11");//如果你的下载需要token，或者有秘钥要求，可以在此处添加header的 key： value
        request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI);//设置下载的网络类型
        request.setVisibleInDownloadsUi(false);//是否显示下载 从Android Q开始会被忽略
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);//下载中与下载完成后都会在通知中显示| 另外可以选 DownloadManager.Request.VISIBILITY_VISIBLE 仅在下载中时显示在通知中,完成后会自动隐藏
        long id = downloadManager.enqueue(request);//加入队列，会返回一个唯一下载id
    }

 

加入列队后，下载就进行了。我们可以在下拉通知栏里看到正在下载的文件。

另外注意 setDestinationInExternalPublicDir方法已经包含根目录路径了，所以直接传入DIRECTORY_DOWNLOADS就可以了，千万不要在导入一个 Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM).getPath() 这样他会自动在创建多层目录

 

查询即将保存的下载文件路径与文件名称

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("调试_临时_log", "this_" + file);
        }
    }

监听下载状态

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

 广播部分代码

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){ //下载状态不等于成功就跳出
            return;
        }
        Uri uri = downloadManager.getUriForDownloadedFile(downloadId);//获取下载完成文件uri
        if (uri == null){
            return;
        }
    }
/**
     * 获取下载状态
     * @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;
    }


}

下载状态查询

    /**
     * 获取下载状态
     *
     * @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  　　 下载等待开始时
     * @see DownloadManager#STATUS_PAUSED   　　 下载暂停
     * @see DownloadManager#STATUS_RUNNING　     正在下载中　
     * @see DownloadManager#STATUS_SUCCESSFUL   下载成功
     * @see DownloadManager#STATUS_FAILED       下载失败
     */
    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;
    }

下载进度查询

  /**
     * 获取当前下载进度
     *
     * @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;

    }

    /**
     * 获取下载总大小
     *
     * @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;
    }

安装下载完成的App

    /**
     * 安装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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