在内部存储中下载 PDF 文件

Question

我正在做 Android 的任务。

我从 URL 下载文件并保存在 android 手机的内部存储/目录中？我的代码写在下面，但这是外部存储代码，我想要内部存储代码。

 public void onClick(View v) {
                    Toast.makeText(Computer.this,"Please Wait until the file is download",Toast.LENGTH_LONG).show();
                    downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
                    Uri uri = Uri.parse("url");
                    DownloadManager.Request request = new DownloadManager.Request(uri);
                    request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE);
                    request.setAllowedOverRoaming(false);
                    request.setTitle("" + "filename" + ".pdf");
                    request.setVisibleInDownloadsUi(true);
                    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
                    Long reference = downloadManager.enqueue(request);
                    request.setDestinationInExternalFilesDir(Environment.DIRECTORY_DOWNLOADS, "/"+ "filename");
                    refid = downloadManager.enqueue(request);
                    Log.e("OUT", "" + refid);

这是外部存储代码，但我想保存在Android手机的内部存储中。

Answer 1

只有您自己的应用可以Access 到应用internal storage 默认android 内置下载管理器无法访问您的应用内部存储，因此您无法在内部存储中下载。

解决方案：

将sd卡中的文件下载为临时文件，下载完成后注册接收器，然后从外部存储复制删除文件后将文件从外部复制到内部存储。

完整代码：

public class MainActivity extends Activity {
    private long enqueue;
    private DownloadManager dm;

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
                    long downloadId = intent.getLongExtra(
                            DownloadManager.EXTRA_DOWNLOAD_ID, 0);
                    DownloadManager.Query query = new DownloadManager.Query();
                    query.setFilterById(enqueue);
                    Cursor c = dm.query(query);
                    if (c.moveToFirst()) {
                        int columnIndex = c
                                .getColumnIndex(DownloadManager.COLUMN_STATUS);
                        if (DownloadManager.STATUS_SUCCESSFUL == c
                                .getInt(columnIndex)) {

                            ImageView view = (ImageView) findViewById(R.id.imageView1);
                            String uriString = c
                                    .getString(c
                                            .getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));

                            Uri a = Uri.parse(uriString);
                            File d = new File(a.getPath());
                           // copy file from external to internal storage..After that delete file from external storage..Code will easily avalible on google.
                            view.setImageURI(a);
                        }
                    }
                }
            }
        };

        registerReceiver(receiver, new IntentFilter(
                DownloadManager.ACTION_DOWNLOAD_COMPLETE));
    }

    public void onClick(View view) {
        dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
        DownloadManager.Request request = new DownloadManager.Request(
                Uri.parse("http://www.vogella.de/img/lars/LarsVogelArticle7.png")).setDestinationInExternalPublicDir("/Sohail_Temp", "test.jpg");
        enqueue = dm.enqueue(request);
    }

    public void showDownload(View view) {
        Intent i = new Intent();
        i.setAction(DownloadManager.ACTION_VIEW_DOWNLOADS);
        startActivity(i);
    }
}

布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="onClick"
        android:text="Start Download"></Button>

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="showDownload"
        android:text="View Downloads"></Button>

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/image_1"></ImageView>
</LinearLayout>

权限：

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

Answer 2

您不能使用DownloadManager 直接下载到your app's portion of internal storage。您将需要use OkHttp 或其他一些进程内 HTTP 客户端 API。

Answer 3

你可以简单地删除这一行，request.setDestinationInExternalFilesDir()

默认情况下，下载内容会保存到共享下载缓存中生成的文件名

From Docs

Answer 4

你可以用这个：

request.setDestinationUri(Uri.fromFile(new File(context.getCacheDir(),"filename.txt")));