FileDownloader at the android it is showing no errors but the download does not start

Question

I am trying to download a simple .pdf file I have tried logs but no errors and nothing. I tried to debug but the same till yesterday it worked like charm but no

Answer 1

The solution is as below, this should fix your problem. There are changes related to API 28 Android Permissions which made your old code obsolete

Access Screen

Output

Code Snapshot

AndroidManifest.xml

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zackdawood">

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


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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:networkSecurityConfig="@xml/network_security_config">
        <provider
            android:name=".GenericFileProvider"
            android:authorities="${applicationId}.fileprovider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/external_files"/>
        </provider>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

GenericFileProvider.java

package com.zackdawood;

import android.support.v4.content.FileProvider;

public class GenericFileProvider extends FileProvider {
}

FileDownloader.java

package com.zackdawood;

import android.util.Log;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class FileDownloader {

    private static final String TAG = "FileDownloader";

    private static final int MEGABYTE = 1024 * 1024;

    public static void downloadFile(String fileUrl, File directory) {
        try {
            Log.v(TAG, "downloadFile() invoked ");
            Log.v(TAG, "downloadFile() fileUrl " + fileUrl);
            Log.v(TAG, "downloadFile() directory " + directory);

            URL url = new URL(fileUrl);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.connect();

            InputStream inputStream = urlConnection.getInputStream();
            FileOutputStream fileOutputStream = new FileOutputStream(directory);
            int totalSize = urlConnection.getContentLength();

            byte[] buffer = new byte[MEGABYTE];
            int bufferLength = 0;
            while ((bufferLength = inputStream.read(buffer)) > 0) {
                fileOutputStream.write(buffer, 0, bufferLength);
            }
            fileOutputStream.close();
            Log.v(TAG, "downloadFile() completed ");

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            Log.e(TAG, "downloadFile() error" + e.getMessage());
            Log.e(TAG, "downloadFile() error" + e.getStackTrace());
        } catch (MalformedURLException e) {
            e.printStackTrace();
            Log.e(TAG, "downloadFile() error" + e.getMessage());
            Log.e(TAG, "downloadFile() error" + e.getStackTrace());
        } catch (IOException e) {
            e.printStackTrace();
            Log.e(TAG, "downloadFile() error" + e.getMessage());
            Log.e(TAG, "downloadFile() error" + e.getStackTrace());
        }
    }
}

MainActivity.java

package com.zackdawood;

import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private static final String[] PERMISSIONS = {android.Manifest.permission.READ_EXTERNAL_STORAGE, android.Manifest.permission.WRITE_EXTERNAL_STORAGE};


    private static boolean hasPermissions(Context context, String... permissions) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && context != null && permissions != null) {
            for (String permission : permissions) {
                if (ActivityCompat.checkSelfPermission(context, permission) != PackageManager.PERMISSION_GRANTED) {
                    return false;
                }
            }
        }
        return true;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.v(TAG, "onCreate() Method invoked ");

        ActivityCompat.requestPermissions(MainActivity.this, PERMISSIONS, 112);

    }

    public void request(View view) {

        ActivityCompat.requestPermissions(MainActivity.this, PERMISSIONS, 112);

    }

    public void view(View view) {
        Log.v(TAG, "view() Method invoked ");

        if (!hasPermissions(MainActivity.this, PERMISSIONS)) {

            Log.v(TAG, "download() Method DON'T HAVE PERMISSIONS ");

            Toast t = Toast.makeText(getApplicationContext(), "You don't have read access !", Toast.LENGTH_LONG);
            t.show();

        } else {
            File d = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);  // -> filename = maven.pdf
            File pdfFile = new File(d, "maven.pdf");

            Log.v(TAG, "view() Method pdfFile " + pdfFile.getAbsolutePath());

            Uri path = FileProvider.getUriForFile(this, BuildConfig.APPLICATION_ID + ".fileprovider", pdfFile);


            Log.v(TAG, "view() Method path " + path);

            Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
            pdfIntent.setDataAndType(path, "application/pdf");
            pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
            pdfIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

            try {
                startActivity(pdfIntent);
            } catch (ActivityNotFoundException e) {
                Toast.makeText(MainActivity.this, "No Application available to view PDF", Toast.LENGTH_SHORT).show();
            }
        }
        Log.v(TAG, "view() Method completed ");

    }

    public void download(View view) {
        Log.v(TAG, "download() Method invoked ");

        if (!hasPermissions(MainActivity.this, PERMISSIONS)) {

            Log.v(TAG, "download() Method DON'T HAVE PERMISSIONS ");

            Toast t = Toast.makeText(getApplicationContext(), "You don't have write access !", Toast.LENGTH_LONG);
            t.show();

        } else {
            Log.v(TAG, "download() Method HAVE PERMISSIONS ");

            //new DownloadFile().execute("http://maven.apache.org/maven-1.x/maven.pdf", "maven.pdf");
            new DownloadFile().execute("http://www.axmag.com/download/pdfurl-guide.pdf", "maven.pdf");

        }

        Log.v(TAG, "download() Method completed ");

    }

    private class DownloadFile extends AsyncTask<String, Void, Void> {

        @Override
        protected Void doInBackground(String... strings) {
            Log.v(TAG, "doInBackground() Method invoked ");

            String fileUrl = strings[0];   // -> http://maven.apache.org/maven-1.x/maven.pdf
            String fileName = strings[1];  // -> maven.pdf
            String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
            File folder = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);

            File pdfFile = new File(folder, fileName);
            Log.v(TAG, "doInBackground() pdfFile invoked " + pdfFile.getAbsolutePath());
            Log.v(TAG, "doInBackground() pdfFile invoked " + pdfFile.getAbsoluteFile());

            try {
                pdfFile.createNewFile();
                Log.v(TAG, "doInBackground() file created" + pdfFile);

            } catch (IOException e) {
                e.printStackTrace();
                Log.e(TAG, "doInBackground() error" + e.getMessage());
                Log.e(TAG, "doInBackground() error" + e.getStackTrace());


            }
            FileDownloader.downloadFile(fileUrl, pdfFile);
            Log.v(TAG, "doInBackground() file download completed");

            return null;
        }
    }
}

strings.xml

<resources>
    <string name="app_name">DemoInternalDownload</string>
    <string name="action_settings">Settings</string>
    <string name="file_view">File View</string>
    <string name="file_download">File Download</string>
    <string name="file_request">Request Access Again</string>

</resources>

external_files.xml

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

network_security_config.xml

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">maven.apache.org</domain>
        <domain includeSubdomains="true">www.axmag.com</domain>
    </domain-config>
</network-security-config>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <Button
            android:id="@+id/button3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="200px"
            android:onClick="download"
            android:text="@string/file_download" />


        <Button
            android:id="@+id/button4"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="200px"
            android:onClick="view"
            android:text="@string/file_view" />

        <Button
            android:id="@+id/button5"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="200px"
            android:onClick="request"
            android:text="@string/file_request" />
    </LinearLayout>


</android.support.design.widget.CoordinatorLayout>

build.gradle

 apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.zackdawood"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}