从资产文件夹读取PDF文件

Question

public void DOCS(View btnDocs)
{   
    File fileBrochure = new File("android.resource://com.project.datastructure/assets/abc.pdf");
    if (!fileBrochure.exists())
    {
         CopyAssetsbrochure();
    } 

    /** PDF reader code */
    File file = new File("android.resource://com.project.datastructure/assets/abc.pdf");        

    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setDataAndType(Uri.fromFile(file),"application/pdf");
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    try 
    {
        getApplicationContext().startActivity(intent);
    } 
    catch (ActivityNotFoundException e) 
    {
         Toast.makeText(Stack_dr.this, "NO Pdf Viewer", Toast.LENGTH_SHORT).show();
    }
}
private void CopyAssetsbrochure() {
    AssetManager assetManager = getAssets();
    String[] files = null;
    try 
    {
        files = assetManager.list("");
    } 
    catch (IOException e){}
    for(int i=0; i<files.length; i++)
    {
        String fStr = files[i];
        if(fStr.equalsIgnoreCase("abc.pdf"))
        {
            InputStream in = null;
            OutputStream out = null;
            try 
            {
              in = assetManager.open(files[i]);
              out = new FileOutputStream("/sdcard/" + files[i]);
              copyFile(in, out);
              in.close();
              in = null;
              out.flush();
              out.close();
              out = null;
              break;
            } 
            catch(Exception e){}
        }
    }
}

 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);
    }
}

我试图从应用程序文件夹中的资产文件夹读取PDF文件。当我点击我的DOCS按钮时，一切都工作得很好，弹出一个窗口让我选择打开PDF的应用程序，即“abc.pdf”，但在选择选项后，我收到一个错误消息：“文件路径无效”。我认为在代码中指定路径时有些问题，请帮忙。

- rick

---

你检查过复制的PDF是否真的存在于你的SD卡中了吗？顺便提一下，你应该使用Environment.getExternalStorageDirectory()指定路径，而不是使用“/sdcard/”。 - Opiatefuchs

PDF文件存在于我的资源文件夹中，将随应用程序一起发布。 - rick

Answer 1

试一试

public class SampleActivity extends Activity
    {

        @Override
        protected void onCreate(Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            CopyReadAssets();

        }

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

            InputStream in = null;
            OutputStream out = null;
            File file = new File(getFilesDir(), "abc.pdf");
            try
            {
                in = assetManager.open("abc.pdf");
                out = openFileOutput(file.getName(), Context.MODE_WORLD_READABLE);

                copyFile(in, out);
                in.close();
                in = null;
                out.flush();
                out.close();
                out = null;
            } catch (Exception e)
            {
                Log.e("tag", e.getMessage());
            }

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

            startActivity(intent);
        }

        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);
            }
        }

    }

请务必包含在内

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

在清单中

- Sunil Kumar

---

那么我们必须写入外部存储吗？不复制，直接打开是否可能？ - Pratik Butani

@sunil 你好，我正在尝试相同的代码，但是出现了“Activity not found”错误。你能帮我解决一下吗？ - poojagupta

@poojagupta 在清单文件中未提及的活动未找到，请检查清单文件。 - Sunil Kumar

@sunil 我已经提到了，但是在 Intent intent = new Intent(Intent.ACTION_VIEW); 这一行仍然出现错误。 intent.setDataAndType( Uri.parse("file://" + getFilesDir() + "/abc.pdf"), "application/pdf");startActivity(intent); - poojagupta

在Google最近加强SD卡安全措施之后，这个还能用吗？ - Jeff Dege

Answer 2

您可以像这样操作（在API 27上进行测试并且可行）

步骤1

在您的应用Gradle中添加以下依赖项：

implementation 'com.github.barteksc:android-pdf-viewer:2.8.2'

步骤2

添加以下XML代码：

<com.github.barteksc.pdfviewer.PDFView
         android:id="@+id/pdfv"
         android:layout_width="match_parent"
         android:layout_height="match_parent"> 
</com.github.barteksc.pdfviewer.PDFView>

第三步

将以下代码添加到您的Java文件中：

public class MainActivity extends AppCompatActivity {

    PDFView pdfView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        pdfView=findViewById(R.id.pdfv);
        pdfView.fromAsset("filename.pdf").load();
    }
}

这些更改将在您创建活动时加载PDF文件。

- Viddyut Khanvilkar

---

@ViddyutKhanvilkar 它只是没有加载任何内容，但可能是我的错误。我现在正在使用另一种方法来处理 PDF。 - Felipe

@Felipe Santiago。你采用了哪种方法？ - David Kariuki

我可以在服务器上使用这种方法来处理在线 PDF 吗？ - David Kariuki

如果我没记错的话，我做过类似这样的事情 https://dev59.com/q2Uq5IYBdhLWcg3wV_Ai#14578661 - Felipe

谢谢！Felipe。 - David Kariuki

barteksc库在apk中占用了很多空间。 - sk1007

Answer 3

虽然这个问题已经得到了回答，但我想分享我的解决方案，因为我认为它更容易实现。

用法：

new OpenLocalPDF(context, 'nameOfPDFStoredInAssets').execute()

这里是OpenLocalPDF类：

public class OpenLocalPDF {

    private static String TAG = OpenLocalPDF.class.getSimpleName();

    private WeakReference<Context> contextWeakReference;
    private String fileName;

    public OpenLocalPDF(Context context, String fileName) {
        this.contextWeakReference = new WeakReference<>(context);
        this.fileName = fileName.endsWith("pdf") ? fileName : fileName + ".pdf";
    }

    public void execute() {

        Context context = contextWeakReference.get();
        if (context != null) {
            new CopyFileAsyncTask().execute();
        }

    }


    private class CopyFileAsyncTask extends AsyncTask<Void, Void, File> {


        final String appDirectoryName = BuildConfig.APPLICATION_ID;
        final File fileRoot = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_DOCUMENTS), appDirectoryName);

        @Override
        protected File doInBackground(Void... params) {

            Context context = contextWeakReference.get();

            AssetManager assetManager = context.getAssets();

            File file = new File(fileRoot, fileName);

            InputStream in = null;
            OutputStream out = null;
            try {

                file.mkdirs();

                if (file.exists()) {
                    file.delete();
                }

                file.createNewFile();


                in = assetManager.open(fileName);
                Log.d(TAG, "In");

                out = new FileOutputStream(file);
                Log.d(TAG, "Out");

                Log.d(TAG, "Copy file");
                copyFile(in, out);

                Log.d(TAG, "Close");
                in.close();

                out.flush();
                out.close();

                return file;
            } catch (Exception e)
            {
                Log.e(TAG, e.getMessage());
            }

            return null;
        }

        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);
            }
        }

        @Override
        protected void onPostExecute(File file) {
            super.onPostExecute(file);

            Context context = contextWeakReference.get();


            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(
                    Uri.fromFile(file),
                    "application/pdf");

            context.startActivity(intent);

        }
    }
}

在Manifest.xml中添加此权限。

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

- cYrixmorten

---

亲爱的@RunLoop，你的评论并不是特别有建设性。我在生产环境中使用它，所以我知道它在我的设置中是有效的。如果你愿意详细说明它对你不起作用的原因，也许我会花时间帮助你解决问题。 - cYrixmorten

Answer 4

就像说sunsil一样，但是针对外部目录的情况。

import android.app.Activity;
import android.content.Intent;
import android.content.res.AssetManager;
import android.net.Uri;
import android.os.Environment;
import android.os.Bundle;
import android.util.Log;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        copyReadAssets();
    }


    private void copyReadAssets()
    {
        AssetManager assetManager = getAssets();

        InputStream in = null;
        OutputStream out = null;

        String strDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)+ File.separator + "Pdfs";
        File fileDir = new File(strDir);
        fileDir.mkdirs();   // crear la ruta si no existe
        File file = new File(fileDir, "example2.pdf");



        try
        {

            in = assetManager.open("example.pdf");  //leer el archivo de assets
            out = new BufferedOutputStream(new FileOutputStream(file)); //crear el archivo


            copyFile(in, out);
            in.close();
            in = null;
            out.flush();
            out.close();
            out = null;
        } catch (Exception e)
        {
            Log.e("tag", e.getMessage());
        }

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(Uri.parse("file://" + Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS) + File.separator + "Pdfs" + "/example2.pdf"), "application/pdf");
        startActivity(intent);
    }

    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);
        }
    }
}

更改类似这样的代码部分：

out = new BufferedOutputStream(new FileOutputStream(file));

之前的例子是针对PDF文件的，如果是txt文件则需要使用下面的例子。

FileOutputStream fos = new FileOutputStream(file);

- Alex Zaraos

Answer 5

这对我有帮助。

第一步：在MainActivity.java中。

public class SampleActivity extends Activity  {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //call this method by passing file name in params.
    readFromAssets("User guide.pdf");
 }

public static void readFromAssets(String fileName) {
    AssetManager assetManager = getAssets();
    InputStream in = null;
    OutputStream out = null;
    File file = new File(mContext.getFilesDir(), fileName);
    try {
        in = assetManager.open(fileName);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            out = mContext.openFileOutput(file.getName(), Context.MODE_PRIVATE);
        } else {
            out = mContext.openFileOutput(file.getName(), Context.MODE_WORLD_READABLE);
        }
        copyFile(in, out);
        in.close();
        in = null;
        out.flush();
        out.close();
        out = null;
    } catch (Exception e) {
        Log.e("tag", e.getMessage());
    }
    Uri pdfFileURI;
    Intent intent = new Intent(Intent.ACTION_VIEW);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        pdfFileURI = FileProvider.getUriForFile(mContext,
                BuildConfig.APPLICATION_ID + ".provider", file);
        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
    } else {
        pdfFileURI = Uri.parse("file://" + mContext.getFilesDir() + "/" + fileName);
    }
    intent.setDataAndType(pdfFileURI, "application/pdf");
    mContext.startActivity(intent);
 }

   private static 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);
     }
   }
}

步骤2：在“res->xml->provider_paths.xml”中创建“provider_paths.xml”。请参见此处。

<?xml version="1.0" encoding="utf-8"?>
<paths>
  <external-path
    name="external"
    path="." />
  <root-path
    name="root"
    path="." />
</paths>

步骤三：在AndroidManifest.xml文件中

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

<application
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppThemeMaterial">

  <!-- INSIDE APPLICATION TAG -->

  <provider
        android:name="androidx.core.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>
</application>     

- Nassa44

Answer 6

这是一种使用zip文件从资产中打开多个PDF文件的方法。

步骤1：将包含pdf列表的zip文件（pdf.zip）复制到资产文件夹中。

步骤2：在Utils类中将PDF写入应用程序内部缓存。

public static void writePDFs(Context context) {
        try {
            InputStream inputStream = context.getApplicationContext().getAssets().open("pdf.zip");
            ZipInputStream zipInputStream = new ZipInputStream(inputStream);
            ZipEntry zipEntry;
            File file = new File(context.getExternalCacheDir().getAbsolutePath(), "PDFs");
            if (!file.getAbsoluteFile().exists()) {
                if (file.mkdir()) {
                    BufferedOutputStream outputStream;
                    byte[] buffer = new byte[1024];
                    int count;
                    while ((zipEntry = zipInputStream.getNextEntry()) != null) {
                        String s1 = file + "/" + zipEntry.getName();
                        File file1 = new File(s1);
                        if (!file1.exists()) {
                            file1.createNewFile();
                        }
                        outputStream = new BufferedOutputStream(new FileOutputStream(file1));
                        while ((count = zipInputStream.read(buffer)) != -1) {
                            outputStream.write(buffer, 0, count);
                        }
                        outputStream.flush();
                        outputStream.close();
                        zipInputStream.closeEntry();
                    }
                }
                zipInputStream.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

步骤3：在Activity的onCreate方法中调用上述函数。

@Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        FileUtils.writePDFs(this);
}

步骤四：在 Utils 类中创建一个通用函数来打开 PDF。

public static void openPDF(Activity activity, String fileName) {
        if (activity == null) return;
        File file = new File(activity.getExternalCacheDir().getAbsolutePath() + "/PDFs" + "/" + fileName);
        Uri docUri = GenericFileProvider.getUriForFile(activity, activity.getApplicationContext().getPackageName(), file);
        try {
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_VIEW);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
                intent.setDataAndType(docUri, "application/pdf");
            } else {
                intent.setDataAndType(Uri.fromFile(file), "application/pdf");
            }
            activity.startActivityForResult(intent, ACTIVITY_VIEW_ATTACHMENT);
        } catch (ActivityNotFoundException e) {
            e.printStackTrace();
        }
    }

步骤5：在Activity中点击视图时调用openPDF函数。

myView.setOnClickListener(v -> ApplicationUtils.openPDF(this, "MyPdfFile.pdf"));

- Shailendra Madda

Answer 7

当尝试通过意图（在我的情况下为PDF）从资产文件夹打开文件时，没有一个答案能够立即为我解决问题。因此，这是我的解决方案，结合了两个杰出的答案，我相信它会帮助某些人。必须适用于api>=24。

一旦您按照此链接进行操作，并添加了自己的GenericFileProvider，并在Application标记中声明它并创建了provider_paths.xml, 只需使用以下类并像下面这样调用：

OpenLocalPDF(this, "YOUR_PDF_NAME_IN_ASSETS_FOLDER.pdf").execute()

OpenLocalPdf.kt:（也要感谢OP https://dev59.com/O2Qn5IYBdhLWcg3wIUFn#41212708）

import android.content.Context
import android.content.Intent
import android.content.res.AssetManager
import android.os.AsyncTask
import android.util.Log
import androidx.core.content.FileProvider
import java.io.File
import java.io.FileOutputStream
import java.io.InputStream
import java.io.OutputStream
import java.lang.ref.WeakReference

class OpenLocalPDF(context: Context?, fileName: String?) {
    private val contextWeakReference: WeakReference<Context?>?
    private val fileName: String?
    fun execute() {
        val context: Context = contextWeakReference!!.get()!!
        if (context != null) {
            CopyFileAsyncTask().execute()
        }
    }

    private inner class CopyFileAsyncTask :
        AsyncTask<Void?, Void?, File?>() {
        val appDirectoryName: String? = co.za.umbiflow.BuildConfig.APPLICATION_ID
        val fileRoot: File? = File(
            android.os.Environment.getExternalStoragePublicDirectory(
                android.os.Environment.DIRECTORY_DOCUMENTS
            ), appDirectoryName
        )

        override fun doInBackground(vararg params: Void?): File? {
            val context: Context = contextWeakReference!!.get()!!
            val assetManager: AssetManager = context.getAssets()
            val file = File(fileRoot, fileName)
            var `in`: InputStream? = null
            var out: OutputStream? = null
            try {
                file.mkdirs()
                if (file.exists()) {
                    file.delete()
                }
                file.createNewFile()
                `in` = assetManager.open(fileName)
                out = FileOutputStream(file)
                copyFile(`in`, out)
                `in`.close()
                out.flush()
                out.close()
                return file
            } catch (e: Exception) {
                Log.e(TAG, e.message)
            }
            return null
        }

        private fun copyFile(`in`: InputStream, out: OutputStream) {
            val buffer = ByteArray(1024)
            var read: Int
            while (`in`.read(buffer).also { read = it } != -1) {
                out.write(buffer, 0, read)
            }
        }

        override fun onPostExecute(file: File?) {
            super.onPostExecute(file)
            val context: Context = contextWeakReference!!.get()!!

            var pdfUri =
                FileProvider.getUriForFile(
                    context,
                    context.packageName + ".provider",
                    file!!
                )

            val intent = Intent()
            intent.action = Intent.ACTION_VIEW
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
            intent.setDataAndType(
                pdfUri,
                "application/pdf"
            )
            context.startActivity(intent)
        }
    }

    companion object {
        private val TAG = OpenLocalPDF::class.java.simpleName
    }

    init {
        contextWeakReference = WeakReference(context)
        this.fileName = if (fileName!!.endsWith("pdf")) fileName else "$fileName.pdf"
    }
}

- David Kroukamp

Answer 8

我成功地使用了cYrixmorten的答案，并使用了OpenLocalPDF类。

但是，Environment.DIRECTORY_DOCUMENTS在Android 18上不被支持。为了支持Android 18-28，我必须进行以下更改。

在"CopyFileAsyncTask"中，更改fileRoot声明：

final File fileRoot = new File(Environment.getExternalStoragePublicDirectory(
        Environment.DIRECTORY_DOCUMENTS), appDirectoryName);

To this:

final File fileRoot = new File(Environment.getExternalStorageDirectory() + "/YourAppName");

在“onPostExecute”中，更改这个：

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(
        Uri.fromFile(file),
        "application/pdf");
context.startActivity(intent);

To this:

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(FileProvider.getUriForFile(context, "com.example.yourappname.provider", file), "application/pdf");
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
context.startActivity(intent);

最后，按照这篇文章所述设置您的清单以支持FileProvider。

- BlueSpectrumz

Answer 9

试试这个：

public String getAssetsPdfPath(Context context) {
String filePath = context.getFilesDir() + File.separator + "myFile.pdf";
File destinationFile = new File(filePath);

try {
FileOutputStream outputStream = new FileOutputStream(destinationFile);
InputStream inputStream = context.getAssets().open("myFile.pdf");
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, length);
}
outputStream.close();
inputStream.close();
} catch (IOException e) {
Log.e(context.getClass().getSimpleName(), "Error.");
}

return destinationFile.getPath();
}

- josef

Answer 10

这段代码适用于所有的Android版本：

活动（Activity）：

import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.res.AssetManager;
import android.net.Uri;
import android.os.Environment;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.content.FileProvider;
import android.util.Log;
import android.widget.Toast;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import unimedbh.UnimedBH.R;


public class MainActivity extends Activity {

    private static final int MY_PERMISSION_REQUEST_STORAGE = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (ContextCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {

           ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, MY_PERMISSION_REQUEST_STORAGE); 

        } else {
            copyReadAssets("YOUR_PDF_NAME.pdf");
        }
    }


    private void copyReadAssets(String fileName) {
        String dirPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/MyFiles";
        File dir = new File(dirPath);

        if (!dir.exists()) {
            dir.mkdirs();
        }

        AssetManager assetManager = getAssets();
        InputStream in = null;
        OutputStream out = null;

        try {
            in = assetManager.open(fileName);
            File outFile = new File(dirPath, fileName);
            out = new FileOutputStream(outFile);
            copyFile(in, out);

            Intent intent = new Intent(Intent.ACTION_VIEW, FileProvider.getUriForFile(this, "com.package.name.fileprovider", outFile));
            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_ACTIVITY_NO_HISTORY);

            startActivity(intent);
        } catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(this, "Error!", Toast.LENGTH_SHORT).show();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    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);
        }
    }
}

Manifest.xml:

<provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="com.package.name.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/file_paths" />
</provider>

file_paths.xml:

<paths>
    <files-path name="app_directory" path="directory/"/>
</paths>

在API 16-28中测试，适用于所有的API！

- Rodrigo Gontijo