Android中文件下载，app更新，我们一般利用的都是 Retrofit或者 Okhttp等实现，但其实Android 早在API 9之后,就为我们提供了DownLoadManager，这是Android提供的系统服务，通过这个服务下载文件，整个过程全部交给了系统负责，免去了我们别的操作。
下面我们就来实地演示一下操作。
测试api sdk28， Android Studio3.4 小米5s Plus
代码如下：
//定义一个成功接口
public interface IDownloadlister { void success(Uri uri); }
工具类，重要的代码我已经移动上来。
/** * Created by Petterp * on 2019-10-26 * Function: 文件下载工具类 */ public class DownloadUtils { public void download() { IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE); //创建下载任务，url即任务链接 DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url)); //指定下载路径及文件名 request.setDestinationInExternalPublicDir(FILE_URI, fileName); //获取下载管理器 final DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE); //一些配置 //允许移动网络与WIFI下载 request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_MOBILE | DownloadManager.Request.NETWORK_WIFI); //是否在通知栏显示下载进度 request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //设置可见及可管理 /*注意，Android Q之后不推荐使用*/ request.setVisibleInDownloadsUi(true); //将任务加入下载队列 assert downloadManager != null; final long id = downloadManager.enqueue(request); BroadcastReceiver receiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { //获取下载id long myDwonloadID = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1); if (myDwonloadID == id) { //获取下载uri Uri uri = downloadManager.getUriForDownloadedFile(myDwonloadID); lister.success(uri); } } }; if (context instanceof Activity) { Activity activity = (Activity) context; activity.registerReceiver(receiver, filter); } } //测试url，下载链接 private String url = "http://qn.yingyonghui.com/apk/653732" + "5/c1d876442e38f2555" + "d85c55a1d8e95b7?sign=a36530f5c08ffbb5d9e" + "53c2d50346eb7&t=5db45f8d&attname=c1d876442e" + "38f2555d85c55a1d8e95b7.apk"; //加.好处是默认隐藏路径 private final String FILE_URI = "/.测试路径/"; private IDownloadlister lister = null; //文件名 private String fileName = "test"; //Context private Context context; public static DownloadUtils builder() { return new DownloadUtils(); } public DownloadUtils setUrl(String url) { this.url = url; return this; } public DownloadUtils setLister(IDownloadlister lister) { this.lister = lister; return this; } public DownloadUtils setFileName(String fileName) { this.fileName = fileName; return this; } public DownloadUtils setContext(Context context) { this.context = context; return this; } }
使用时，这里下载了个app
DownloadUtils.builder() .setContext(this) .setLister(new IDownloadlister() { @Override public void success(Uri uri) { Intent install = new Intent(Intent.ACTION_VIEW); install.setDataAndType(uri, "application/vnd.android.package-archive"); install.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); startActivity(install); } }) .download();
最后记得给权限啊，切记。
很简单吧，关于更多的操作，比如下载进度，DownloadManager并没有提供具体方法，不过我们可以通过定时获取已下载大小，然后计算相应的进度值。
