Как извлечь файл PDF с сервера и показать в приложении и как?

Question

Как преобразовать PDF-файл в Base64 в android & как извлечь файл pdf с сервера с помощью json (HTTPURLConection)?

Answer 1

Вы можете конвертировать PDF в base64 в андроида с помощью

File dir = Environment.getExternalStorageDirectory(); 
    File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext"); 
    String encodeFileToBase64Binary = encodeFileToBase64Binary(yourFile); 

    private static String encodeFileToBase64Binary(File fileName) throws IOException { 
      byte[] bytes = loadFile(fileName); 
      byte[] encoded = Base64.encodeBase64(bytes); 
      String encodedString = new String(encoded); 
      return encodedString; 
    } 

И вы можете сослаться на эту ссылку, чтобы работать с вашим вторым вопросом Retrieve PDF from server

Answer 2

You can download a PDF fie from server using following Code.. 


avtivity_main.xml 

<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="com.example.aman.pdfserver.MainActivity"> 

    <Button 
     android:id="@+id/button1" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentTop="true" 
     android:layout_marginTop="15dp" 
     android:text="download" 
     android:onClick="download" /> 

    <Button 
     android:id="@+id/button2" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentRight="true" 
     android:layout_below="@+id/button1" 
     android:layout_marginTop="38dp" 
     android:text="view" 
     android:onClick="view" /> 

</RelativeLayout> 


MainActivity.java 


    package com.example.aman.pdfserver; 

    import android.support.v7.app.AppCompatActivity; 
    import android.os.Bundle; 
    import java.io.File; 
    import java.io.IOException; 

    import android.app.Activity; 
    import android.app.ProgressDialog; 
    import android.content.ActivityNotFoundException; 
    import android.content.Intent; 
    import android.net.Uri; 
    import android.os.AsyncTask; 
    import android.os.Bundle; 
    import android.os.Environment; 
    import android.util.Log; 
    import android.view.View; 
    import android.widget.Toast; 

    public class MainActivity extends AppCompatActivity { 

     // Progress dialog 
     private ProgressDialog pDialog; 

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

      pDialog = new ProgressDialog(this); 
      pDialog.setMessage("Please wait..."); 
      pDialog.setCancelable(false); 
     } 


     public void download(View v) 
     { 
      new DownloadFile().execute("http://maven.apache.org/maven-1.x/maven.pdf", "maven.pdf"); 
     } 

     public void view(View v) 
     { 
      File pdfFile = new File(Environment.getExternalStorageDirectory() + "/testthreepdf/" + "maven.pdf"); // -> filename = maven.pdf 
      Uri path = Uri.fromFile(pdfFile); 
      Intent pdfIntent = new Intent(Intent.ACTION_VIEW); 
      pdfIntent.setDataAndType(path, "application/pdf"); 
      pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 

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

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

      @Override 
      protected Void doInBackground(String... strings) { 
       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 = new File(extStorageDirectory, "testthreepdf"); 
       folder.mkdir(); 

       File pdfFile = new File(folder, fileName); 

       try{ 
        pdfFile.createNewFile(); 
       }catch (IOException e){ 
        e.printStackTrace(); 
       } 
       FileDownloader.downloadFile(fileUrl, pdfFile); 
       return null; 
      } 
     } 


    } 


FileDownloader.java 


package com.example.aman.pdfserver; 

/** 
* Created by Aman on 13-12-2016. 
*/ 

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 int MEGABYTE = 1024 * 1024; 

    public static void downloadFile(String fileUrl, File directory){ 
     try { 

      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(); 
     } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
}