Question

我正在尝试展示＆＃34; NEFT.pdf＆＃34;存储在我的Android应用程序的资产文件夹中的文件。
以下代码在API 25

之前完全正常

private void CopyReadAssets(String filename) {
    AssetManager assetManager = getAssets();
    InputStream in = null;
    OutputStream out = null;
    File file = new File(getFilesDir(), filename);

    try {
        in = assetManager.open(filename);
        out = openFileOutput(file.getName(), Context.MODE_WORLD_READABLE);

        copyFile(in, out);
        in.close();
        in = null;
        out.flush();
        out.close();
        out = null;


        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(
                Uri.parse("file://" + getFilesDir() + "/"+filename), "application/pdf");

        startActivity(intent);
    } catch (Exception e)
    {
        Toast.makeText(PdfFilesList.this, "cra: "+e.toString(), Toast.LENGTH_SHORT).show();
    }
}

此代码不适用于API 25及更高版本。它不再支持错误 MODE_WORLD_READABLE 。
我将其更改为 MODE_PRIVATE ，但这又给我一个错误

android.os.fileuriexposedexception通过intent.getdata（）暴露在app之外。
所以我应用了Developer.Android.com中解释的概念。
这是我在错误日志中得到的：

E / DisplayData：openFd：java.io.FileNotFoundException：没有这样的文件或目录

E / PdfLoader：无法加载文件（不打开）显示数据[PDF：NEFT.pdf] + ContentOpenable，uri：content：//com.user.plansmart .provider / pdf_files / NEFT.pdf

uri看起来对我不对。任何人都可以帮助我找到错误。

以下是清单文件中的提供程序元素。

<provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="${applicationId}.provider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/provider_paths"/>
    </provider>

这是 provider_paths.xml 文件

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path name="external_files" path="."/>
<files-path name="pdf_files" path="pdf/"/>

这是显示pdf文件的Android代码

private void displayFile(String filename) {
    try {
        File filePath = new File(getApplicationContext().getFilesDir(), "pdf");
        File newFile =  new File(filePath, filename);

        //new version
        Uri fileUri = FileProvider.getUriForFile(PdfFilesList.this,
                BuildConfig.APPLICATION_ID + ".provider", newFile);

        getApplicationContext().grantUriPermission(PACKAGE_NAME,
                            fileUri, Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(fileUri, "application/pdf");
        intent.setFlags(FLAG_GRANT_READ_URI_PERMISSION | FLAG_GRANT_WRITE_URI_PERMISSION);
        startActivity(intent);
    }catch (Exception e){
        e.printStackTrace();
        Toast.makeText(PdfFilesList.this, "df "+e.toString(), Toast.LENGTH_SHORT).show();
    }
}

Answer 1

因为您想在单独的应用程序（例如Adobe Reader）中显示PDF文件，我希望执行以下操作： -

private void CopyReadAssets()
        {
            AssetManager assetManager = getActivity().getAssets();

            InputStream in = null;
            OutputStream out = null;
            String state = Environment.getExternalStorageState();
            if (!Environment.MEDIA_MOUNTED.equals(state)) {
                Toast.makeText(getActivity(), "External Storage is not Available", Toast.LENGTH_SHORT).show();
            }
            File pdfDir = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/PDFs");
            if (!pdfDir.exists()) {
                pdfDir.mkdir();
            }
            File file = new File(pdfDir + "/abc.pdf");

            try
            {
                in = assetManager.open("abc.pdf");
                out = new BufferedOutputStream(new FileOutputStream(file));
                copyFile(in, out);
                in.close();
                in = null;
                out.flush();
                out.close();
                out = null;
            } catch (Exception e)
            {
                Log.e("tag", e.getMessage());
            }
            if (file.exists()) //Checking for the file is exist or not
            {
                Uri path = Uri.fromFile(file);
                Intent objIntent = new Intent(Intent.ACTION_VIEW);
                objIntent.setDataAndType(path, "application/pdf");
                objIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                Intent intent1 = Intent.createChooser(objIntent, "Open PDF with..");
                try {
                    startActivity(intent1);
                } catch (ActivityNotFoundException e) {
                    Toast.makeText(getActivity(), "Activity Not Found Exception ", Toast.LENGTH_SHORT).show();
                }
            } else {
                Toast.makeText(getActivity(), "The file not exists! ", Toast.LENGTH_SHORT).show();
            }
        }

将副本文件复制到设备存储器中： -

private void copyFile(InputStream in, OutputStream out) throws IOException
    {
        byte[] buffer = new byte[1024];
        int read;
        while ((read = in.read(buffer)) != -1)
        {
            out.write(buffer, 0, read);
        }
    }

使用以下权限

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

尝试使用fileProvider从assets文件夹打开PDF文件，但它给出了FileNotFoundException：没有这样的文件或目录

1 个答案: