我已升級到 android 11。我在下載 PDF 檔案時遇到問題。
我用過這個代碼：
private void createFile(Uri pickerInitialUri, String title) {
Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("application/pdf");
intent.putExtra(Intent.EXTRA_TITLE, title);
// Optionally, specify a URI for the directory that should be opened in
// the system file picker when your app creates the document.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, pickerInitialUri);
}
startActivityForResult(intent, CREATE_FILE);
}
檔案已創建，但檔案為空。我仍然無法保存下載的pdf檔案。
我曾經使用 DownloadManager 請求從網路下載 pdf 檔案。
DownloadManager downloadManager = (DownloadManager) this.getSystemService(Context.DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(uri);
if (SDK_INT > Build.VERSION_CODES.Q) {
// Uri uri1 = Uri.fromFile(new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "")); //before android 11 this was working fine
// Uri uri1 = Uri.fromFile(new File(getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS), ""));
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE)
.setAllowedOverRoaming(true).setTitle(title strDate ".pdf")
.setDescription(description)
//.setDestinationUri(uri1) // before android 11 it was working fine.
.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, title strDate ".pdf") // file is not saved on this directory.
.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);//to show the DOWNLOAD notification when completed
// createFile(uri , title strDate ".pdf"); // for new scoped storage
} else {
request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE)
.setAllowedOverRoaming(true).setTitle(title strDate ".pdf")
.setDescription(description)
.setDestinationInExternalPublicDir(FileUtils.downloadPdfDestination(), title strDate ".pdf")
.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //to show the DOWNLOAD notification when completed
}
long PDF_DOWNLOAD_ID = downloadManager.enqueue(request);```
uj5u.com熱心網友回復：
ACTION_CREATE_DOCUMENT 用于創建新檔案。如果一個已經存在，它將被覆寫。如果要查看現有檔案，請使用 ACTION_VIEW。
當然，您發布的任何代碼實際上都不會下載 PDF。如果您需要這方面的幫助，請發布您的 DownloadManager 代碼。
uj5u.com熱心網友回復：
檢查此代碼片段：
override fun startDownload(url: String, one rror: (e: Exception) -> Unit) {
try {
val request = DownloadManager.Request(Uri.parse(url))
request.setDestinationInExternalPublicDir(
Environment.DIRECTORY_DOWNLOADS,
UUID.randomUUID().toString()
)
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_ONLY_COMPLETION)
(context.getSystemService(DOWNLOAD_SERVICE) as DownloadManager).enqueue(request)
} catch (e: Exception) {
e.printStackTrace()
one rror.invoke(e)
}
}
Android 11通過使用DownloadMangerAPI 可以正常作業。
uj5u.com熱心網友回復：
使用以下代碼下載和查看 pdf。
首先，您需要rxjava為后臺任務應用依賴項。
implementation 'io.reactivex.rxjava2:rxandroid:2.1.1'
WRITE_EXTERNAL_STORAGE在呼叫以下方法之前不要忘記檢查權限。還要檢查INTERNET權限。
然后使用下面的方法在后臺執行操作。
private void downloadAndOpenInvoice() {
mDialog.show();
Observable.fromCallable(() -> {
String pdfName = "Invoice_" Calendar.getInstance().getTimeInMillis() ".pdf";
String pdfUrl = "https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf";
File file = CommonUtils.downloadFile(mActivity, pdfUrl, pdfName,mDialog);
return file;
}).subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(file -> {
CommonUtils.viewPdf(file, mActivity, mDialog);
});
}
要從 url 下載檔案，請使用以下代碼段
public static File downloadFile(Activity mActivity, String url, String fileName, CustomDialog mDialog) {
// write the document content
File fileDir = new File(CommonUtils.getAppDir(mActivity, "Invoice")); //Invoice folder inside your app directory
if (!fileDir.exists()) {
boolean mkdirs = fileDir.mkdirs();
}
File pdfFile = new File(CommonUtils.getAppDir(mActivity, "Invoice"), fileName); //Invoice folder inside your app directory
try {
URL u = new URL(url);
URLConnection conn = u.openConnection();
int contentLength = conn.getContentLength();
DataInputStream stream = new DataInputStream(u.openStream());
byte[] buffer = new byte[contentLength];
stream.readFully(buffer);
stream.close();
DataOutputStream fos = new DataOutputStream(new FileOutputStream(pdfFile));
fos.write(buffer);
fos.flush();
fos.close();
} catch (IOException e) {
e.printStackTrace();
if (mDialog.isShowing()) {
mDialog.dismiss();
}
Toast.makeText(mActivity, "Something wrong: " e.toString(), Toast.LENGTH_LONG).show();
}
return pdfFile;
}
對于應用程式目錄
public static String getAppDir(Context context, String folderName) {
return context.getExternalFilesDir(null).getAbsolutePath() File.separator folderName File.separator;
}
使用以下代碼查看pdf
public static void viewPdf(File pdfFile, Activity mActivity, CustomDialog mDialog) {
Uri uri = FileProvider.getUriForFile(mActivity, mActivity.getApplicationContext().getPackageName() ".provider", pdfFile);
// Setting the intent for pdf reader
Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
pdfIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
pdfIntent.setDataAndType(uri, "application/pdf");
//pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
try {
mActivity.runOnUiThread(new Runnable() {
@Override
public void run() {
if (mDialog.isShowing()) {
mDialog.dismiss();
}
}
});
mActivity.startActivity(pdfIntent);
Log.e("Invoice - PDF", pdfFile.getPath());
} catch (ActivityNotFoundException e) {
mActivity.runOnUiThread(new Runnable() {
@Override
public void run() {
if (mDialog.isShowing()) {
mDialog.dismiss();
}
}
});
e.printStackTrace();
Log.e("Invoice - PDF", "Can't read pdf file");
Toast.makeText(mActivity, "Can't read pdf file", Toast.LENGTH_SHORT).show();
}
}
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標籤：爪哇 安卓 文件 下载 android-11