【发布时间】：2025-12-23 02:20:11
【问题描述】：
公共类 PdfRendererBasicFragment 扩展 Fragment 实现 View.OnClickListener {
/**
* Key string for saving the state of current page index.
*/
private static final String STATE_CURRENT_PAGE_INDEX = "current_page_index";
public static final int EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE = 2;
/**
* File descriptor of the PDF.
*/
/**
* {@link android.graphics.pdf.PdfRenderer} to render the PDF.
*/
private PdfRenderer mPdfRenderer;
/**
* Page that is currently shown on the screen.
*/
private PdfRenderer.Page mCurrentPage;
/**
* {@link android.widget.ImageView} that shows a PDF page as a {@link android.graphics.Bitmap}
*/
private ImageView mImageView;
/**
* {@link android.widget.Button} to move to the previous page.
*/
private Button mButtonPrevious;
/**
* {@link android.widget.Button} to move to the next page.
*/
private Button mButtonNext;
private Bundle copySavedInstanceState;
public PdfRendererBasicFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_pdf_renderer_basic, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// Retain view references.
mImageView = (ImageView) view.findViewById(R.id.image);
mButtonPrevious = (Button) view.findViewById(R.id.previous);
mButtonNext = (Button) view.findViewById(R.id.next);
// Bind events.
mButtonPrevious.setOnClickListener(this);
mButtonNext.setOnClickListener(this);
mImageView.setOnClickListener(this);
copySavedInstanceState = savedInstanceState;
while (true) {
int rc = ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (rc == PackageManager.PERMISSION_GRANTED)
break;
}
// Show the first page by default.
int index = 0;
// If there is a savedInstanceState (screen orientations, etc.), we restore the page index.
if (null != copySavedInstanceState) {
index = copySavedInstanceState.getInt(STATE_CURRENT_PAGE_INDEX, 0);
}
Log.d("check","index : " + index);
showPage(index);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
int rc = ActivityCompat.checkSelfPermission(getContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (rc == PackageManager.PERMISSION_GRANTED) {
try {
openRenderer(activity);
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(activity, "Error! " + e.getMessage(), Toast.LENGTH_SHORT).show();
activity.finish();
}
} else {
requestExternalStoragePermission();
}
}
@Override
public void onDetach() {
try {
closeRenderer();
} catch (IOException e) {
e.printStackTrace();
}
super.onDetach();
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (null != mCurrentPage) {
outState.putInt(STATE_CURRENT_PAGE_INDEX, mCurrentPage.getIndex());
}
}
private void requestExternalStoragePermission() {
final String[] permissions = new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE};
if (!ActivityCompat.shouldShowRequestPermissionRationale(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
ActivityCompat.requestPermissions(getActivity(), permissions, EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
return;
}
final Activity thisActivity = getActivity();
View.OnClickListener listener = new View.OnClickListener() {
@Override
public void onClick(View view) {
ActivityCompat.requestPermissions(thisActivity, permissions,
EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
}
};
}
@Override
public void onRequestPermissionsResult(int requestCode,
@NonNull String[] permissions,
@NonNull int[] grantResults) {
if (requestCode != EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE) {
Log.d("TAG", "Got unexpected permission result: " + requestCode);
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
return;
}
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Log.d("TAG", "Camera permission granted - initialize the camera source");
// we have permission, so can read SD Card now.
try {
openRenderer(getActivity());
} catch (IOException e) {
e.printStackTrace();
Toast.makeText(getActivity(), "Error! " + e.getMessage(), Toast.LENGTH_SHORT).show();
getActivity().finish();
}
return;
}
Log.e("TAG", "Permission not granted: results len = " + grantResults.length +
" Result code = " + (grantResults.length > 0 ? grantResults[0] : "(empty)"));
DialogInterface.OnClickListener listener = new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
}
};
}
/**
* Sets up a {@link android.graphics.pdf.PdfRenderer} and related resources.
*/
private void openRenderer(Context context) throws IOException {
File file = new File("/sdcard/Download/test.pdf");
mPdfRenderer = new PdfRenderer(ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY));
}
/**
* Closes the {@link android.graphics.pdf.PdfRenderer} and related resources.
*
* @throws java.io.IOException When the PDF file cannot be closed.
*/
private void closeRenderer() throws IOException {
if (null != mCurrentPage) {
mCurrentPage.close();
}
mPdfRenderer.close();
}
/**
* Shows the specified page of PDF to the screen.
*
* @param index The page index.
*/
private void showPage(int index) {
if (mPdfRenderer.getPageCount() <= index) {
return;
}
// Make sure to close the current page before opening another one.
if (null != mCurrentPage) {
mCurrentPage.close();
}
// Use `openPage` to open a specific page in PDF.
mCurrentPage = mPdfRenderer.openPage(index);
// Important: the destination bitmap must be ARGB (not RGB).
Bitmap bitmap = Bitmap.createBitmap(mCurrentPage.getWidth(), mCurrentPage.getHeight(),
Bitmap.Config.ARGB_8888);
// Here, we render the page onto the Bitmap.
// To render a portion of the page, use the second and third parameter. Pass nulls to get
// the default result.
// Pass either RENDER_MODE_FOR_DISPLAY or RENDER_MODE_FOR_PRINT for the last parameter.
mCurrentPage.render(bitmap, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
// We are ready to show the Bitmap to user.
mImageView.setImageBitmap(bitmap);
updateUi();
}
/**
* Updates the state of 2 control buttons in response to the current page index.
*/
private void updateUi() {
int index = mCurrentPage.getIndex();
int pageCount = mPdfRenderer.getPageCount();
mButtonPrevious.setEnabled(0 != index);
mButtonNext.setEnabled(index + 1 < pageCount);
getActivity().setTitle(getString(R.string.app_name_with_index, index + 1, pageCount));
}
/**
* Gets the number of pages in the PDF. This method is marked as public for testing.
*
* @return The number of pages.
*/
public int getPageCount() {
return mPdfRenderer.getPageCount();
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.previous: {
// Move to the previous page
showPage(mCurrentPage.getIndex() - 1);
break;
}
case R.id.next: {
// Move to the next page
Log.d("name", mCurrentPage.getIndex() + "");
showPage(mCurrentPage.getIndex() + 1);
break;
}
case R.id.image: {
Log.d("name", mCurrentPage.getIndex() + "");
break;
}
}
}
}
嗨，这是我的代码。
我尝试修复。但进展并不顺利。
问题是这样的。
当我执行这个应用程序时。 Android 请求权限，我同意。
但当时 android 在 'openRenderer(activity)' 完成之前执行 'onViewCreated(View view, Bundle savedInstanceState)' 方法。 所以 'showPage(index)' 会引发一些错误。然后（我的意思是权限已经批准，并再次执行）应用程序运行良好。
但我想解决这个问题。
我觉得
第一次，onAttach(Activity activity)执行 并在获得许可后， onAttach（活动活动）和 onViewCreated（查看视图，捆绑 savedInstanceState） 方法似乎同时运行。
请给我建议。
谢谢。
【问题讨论】：
-
我尝试定位 showPage(index);在 openRenderer(activity); 之后
-
但它不起作用。
-
结果出来了。 onRequestPermissionsResult 没有调用。我会检查原因。
-
onRequestPermissionsResult 没有调用，因为我使用了 ActivityCompat.requestPermissions(thisActivity, permissions, EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
-
使用 requestPermissions(permissions, EXTERNAL_STORAGE_PERMISSION_REQUEST_CODE);
标签： android-fragments permissions request