java - 下载 PDF 并将其保存在 SD 卡上未找到

Question

我正在尝试从网址下载 pdf，然后保存并阅读它。但当我尝试阅读它时，出现错误 java.io.IOException:/storage/emulated/0/pdf/menu.pdf not found as file or resource. 。有什么想法吗？

这是我的下载器类:

public class Downloader {

    public static void DownloadFile(String fileURL, File directory) {
        try {

            FileOutputStream f = new FileOutputStream(directory);
            URL u = new URL(fileURL);
            HttpURLConnection c = (HttpURLConnection) u.openConnection();
            c.setRequestMethod("GET");
            c.setDoOutput(true);
            c.connect();

            InputStream in = c.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = in.read(buffer)) > 0) {
                f.write(buffer, 0, len1);
            }
            f.close();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

以及下载和阅读 pdf 的行:

String extStorageDirectory = Environment.getExternalStorageDirectory().getAbsolutePath()
            .toString();
    File folder = new File(extStorageDirectory, "pdf");
    folder.mkdir();
    File file = new File(folder, "menu.pdf");
    try {
        file.createNewFile();
    } catch (IOException e1) {
        e1.printStackTrace();
    }
    Downloader.DownloadFile("http://webdfd.mines-ales.fr/restau/Menu_Semaine.pdf", file);
    PdfReader reader = new PdfReader(Environment.getExternalStorageDirectory().getAbsolutePath()+"/pdf/menu.pdf");

这是错误:

    05-02 13:59:01.138 16747-16747/? I/art: Not late-enabling -Xcheck:jni (already on)    
05-02 13:59:01.139 16747-16747/? W/art: Unexpected CPU variant for X86 using defaults: x86    
05-02 13:59:01.676 16747-16747/com.example.yohannmbp.ematoufaire I/InstantRun: starting instant run server: is main process    
05-02 13:59:01.868 16747-16747/com.example.yohannmbp.ematoufaire W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
05-02 13:59:02.440 16747-16787/com.example.yohannmbp.ematoufaire D/NetworkSecurityConfig: No Network Security Config specified, using platform default
05-02 13:59:02.783 16747-16795/com.example.yohannmbp.ematoufaire I/OpenGLRenderer: Initialized EGL, version 1.4
05-02 13:59:02.783 16747-16795/com.example.yohannmbp.ematoufaire D/OpenGLRenderer: Swap behavior 1
05-02 13:59:02.783 16747-16795/com.example.yohannmbp.ematoufaire W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
05-02 13:59:02.783 16747-16795/com.example.yohannmbp.ematoufaire D/OpenGLRenderer: Swap behavior 0
05-02 13:59:03.029 16747-16747/com.example.yohannmbp.ematoufaire W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
05-02 13:59:11.011 16747-16747/com.example.yohannmbp.ematoufaire W/System.err: java.io.IOException: No such file or directory
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.UnixFileSystem.createFileExclusively0(Native Method)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.File.createNewFile(File.java:948)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.example.yohannmbp.ematoufaire.MenuFragment.onCreateView(MenuFragment.java:106)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
05-02 13:59:11.012 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Handler.handleCallback(Handler.java:751)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Looper.loop(Looper.java:154)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6119)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
05-02 13:59:11.013 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
05-02 13:59:11.015 16747-16747/com.example.yohannmbp.ematoufaire W/System.err: java.io.FileNotFoundException: /storage/emulated/0/pdf/menu.pdf (No such file or directory)
05-02 13:59:11.015 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.FileOutputStream.open(Native Method)
05-02 13:59:11.016 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
05-02 13:59:11.016 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:169)
05-02 13:59:11.016 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.example.yohannmbp.ematoufaire.Downloader.DownloadFile(Downloader.java:18)
05-02 13:59:11.016 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.example.yohannmbp.ematoufaire.MenuFragment.onCreateView(MenuFragment.java:110)
05-02 13:59:11.017 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)
05-02 13:59:11.017 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299)
05-02 13:59:11.017 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
05-02 13:59:11.017 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2013)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:710)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Handler.handleCallback(Handler.java:751)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:95)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.os.Looper.loop(Looper.java:154)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:6119)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
05-02 13:59:11.018 16747-16747/com.example.yohannmbp.ematoufaire W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
05-02 13:59:11.088 16747-16752/com.example.yohannmbp.ematoufaire I/art: Do partial code cache collection, code=30KB, data=29KB
05-02 13:59:11.089 16747-16752/com.example.yohannmbp.ematoufaire I/art: After code cache collection, code=23KB, data=25KB
05-02 13:59:11.089 16747-16752/com.example.yohannmbp.ematoufaire I/art: Increasing code cache capacity to 128KB
05-02 13:59:11.127 16747-16747/com.example.yohannmbp.ematoufaire I/System.out: java.io.IOException: /storage/emulated/0/pdf/menu.pdf not found as file or resource.

Answer 1

private class DownloadTask extends AsyncTask<String, Integer, String> {
        private Context context;
        private PowerManager.WakeLock mWakeLock;

        public DownloadTask(Context context) {
        this.context = context;
    }

**strong text**    @Override
    protected String doInBackground(String... sUrl) {
        InputStream input = null;
        OutputStream output = null;
        HttpURLConnection connection = null;
        try {
            URL url = new URL(AppConstant.BASE_URL + URLEncoder.encode(sUrl[0], "UTF-8"));
            connection = (HttpURLConnection) url.openConnection();
            connection.connect();

            // expect HTTP 200 OK, so we don't mistakenly save error report
            // instead of the file
            if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                return "Server returned HTTP " + connection.getResponseCode()
                        + " " + connection.getResponseMessage();
            }

            // this will be useful to display download percentage
            // might be -1: server did not report the length
            int fileLength = connection.getContentLength();

            // download the file
            fileName = sUrl[0].substring(sUrl[0].lastIndexOf("/") + 1,
                    sUrl[0].length());
            input = connection.getInputStream();
            output = new FileOutputStream(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/" + fileName);

            byte data[] = new byte[4096];
            long total = 0;
            int count;
            while ((count = input.read(data)) != -1) {
                // allow canceling with back button
                if (isCancelled()) {
                    input.close();
                    return null;
                }
                total += count;
                // publishing the progress....
                if (fileLength > 0) // only if total length is known
                    publishProgress((int) (total * 100 / fileLength));
                output.write(data, 0, count);
            }
        } catch (Exception e) {
            return e.toString();
        } finally {
            try {
                if (output != null)
                    output.close();
                if (input != null)
                    input.close();
            } catch (IOException ignored) {
            }

            if (connection != null)
                connection.disconnect();
        }
        return null;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // take CPU lock to prevent CPU from going off if the user
        // presses the power button during download
        PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
        mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,
                getClass().getName());
        mWakeLock.acquire();
        mProgressDialog.show();
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        super.onProgressUpdate(progress);
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.setMax(100);
        mProgressDialog.setProgress(progress[0]);
    }

    @Override
    protected void onPostExecute(String result) {
        mWakeLock.release();
        mProgressDialog.dismiss();
        if (result != null)
            Toast.makeText(context, "Download error: File is not Found.", Toast.LENGTH_LONG).show();
        else {
            new AlertDialog.Builder(context)
                    //.setTitle("Delete entry")
                    .setMessage("File Downloaded Successfully. Do you want to open it?")
                    .setPositiveButton("Open", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            try {
                                File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + "/" + fileName);
                                MimeTypeMap map = MimeTypeMap.getSingleton();
                                String ext = MimeTypeMap.getFileExtensionFromUrl(file.getName());
                                String type = map.getMimeTypeFromExtension(ext);

                                if (type == null)
                                    type = "*/*";

                                Intent intent = new Intent(Intent.ACTION_VIEW);
                                Uri data = Uri.fromFile(file);

                                intent.setDataAndType(data, type);

                                context.startActivity(intent);
                            } catch (ActivityNotFoundException e) {
                                Toast.makeText(context, "There is no app registered to handle the type of file selected.", Toast.LENGTH_SHORT).show();
                            }

                        }
                    })
                    .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            // do nothing
                        }
                    })
                    .setIcon(android.R.drawable.ic_dialog_alert)
                    .show();
            Toast.makeText(context, "File downloaded", Toast.LENGTH_SHORT).show();
        }
    }
}