Downloading a file programatically, from your Android application

I’m  lazy to redo work..So, presenting working code right infront of you :-).I think comments are sufficient to explain how the things are working....

package org.sample.example.download;

import java.io.DataInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.net.URL;

import java.net.URLConnection;

import android.content.Context;

import android.util.Log;

public class DownLoadManager {

      //MAKE SURE YOU HAVE SET INTERNET PERMISSION ....

     

public void startDownLoad(Context context, String sourceUrl,String destinationPath)

      {          

new DownLoadFileThread(context, sourceUrl, destinationPath).start();

      }

     

      private static class DownLoadFileThread extends Thread{

           

            Context context=null;

            String sourceUrl=null;

            String destinationPath=null;

           

            /*

             * Make sure sourceUrl ends with a file to download and not a folder!.

             *  Same with destinationPath.

             *  Ex:

             * 

             *  sourceUrl="http://www.tempurl.com/image1.jpg"

             *  destinationPath="data/data/<package-name>/files/image1.jpg"

             */

public DownLoadFileThread(Context context, String sourceUrl,String destinationPath)

            {

                  this.context=context;

                  this.sourceUrl=sourceUrl;

                  this.destinationPath=destinationPath;

            }

           

            @Override

            public void run()

            {

                  downLoadFileFromServer();

            }

           

            public boolean downLoadFileFromServer()

            {

                  Log.v("DEBUG", "sourceUrl: "+sourceUrl);

                  Log.v("DEBUG", "destinationPath: "+destinationPath);             

                 

                  InputStream urlInputStream=null;

                 

                  URLConnection urlConnection ;

                 

            try

              {

                  //Form a new URL

                  URL finalUrl =new URL(sourceUrl);

                 

                  urlConnection = finalUrl.openConnection();  

                  //Get the size of the (file) inputstream from server..

                  int contentLength=urlConnection.getContentLength();

                 

                  Log.d("1URL","Streaming from "+sourceUrl+ "....");               

      DataInputStream stream = new DataInputStream(finalUrl.openStream());

                 

      Log.d("2FILE","Buffering the received stream(size="+contentLength+") ...");

                  byte[] buffer = new byte[contentLength];

                  stream.readFully(buffer);

                  stream.close();

      Log.d("3FILE","Buffered successfully(Buffer.length="+buffer.length+")...."); 

                 

                  if (buffer.length>0)

                  {

                           try

                           {                   

                                 Log.d("4FILE","Creating the new file..");                                 

                                 FileOutputStream fos = context.openFileOutput(destinationPath, Context.MODE_PRIVATE);

Log.d("5FILE","Writing from buffer to the new file..");

                               fos.write(buffer);

                               fos.flush();

                               fos.close();

                               Log.d("6.1FILE","Created the new file & returning 'true'.."); 

                               return true;

                           }

                           catch (Exception e)

                           {

                                 // TODO Auto-generated catch block

                                 Log.e("7ERROR", "Could not create new file(Path="+destinationPath+") ! & returning 'false'.......");

                                 e.printStackTrace();

                                 return false;

                                 /*Toast.makeText(context, e.toString(), Toast.LENGTH_LONG).show();*/

                           }

                  }

                  else

                  {           

                        //Could not download the file...

Log.e("8ERROR", "Buffer size is zero ! & returning 'false'.......");

                        return false;

                  }

              }

            catch (Exception e)

              {

Log.e("9ERROR", "Failed to open urlConnection/Stream the connection(From catch block) & returning 'false'..");

                  System.out.println("Exception: " + e);

                  e.printStackTrace();

                  return false;

              }

              finally

              {

                  try

                  {

                        Log.d("10URL", "Closing urlInputStream... ");

                      if (urlInputStream != null) urlInputStream.close();

                     

                  }

                  catch (Exception e)

                  {

Log.e("11ERROR", "Failed to close urlInputStream(From finally block)..");

                  }

              }      

            }      

      }

             

}

Once done, you may find your file under DDMS>File Explorer>data/data/package_name/files/

I admit that this isn’t a better way to handle downloading files over internet! You should handle such things asynchronously.  I will be shortly posting the same over here...Till then keep visiting ;-)

Happy coding guys :-)

Writing-to and Reading-from a file in Android

I’m  lazy to redo work..So, presenting working code right infront of you :-).I think comments are sufficient to explain how the things are working....

package org.sample.example.download;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import android.content.Context;

public class ReadWriteFileManager {

     

     

       public String readFromFile(Context context,String sourceFileName)

       {

             /*

              * Reading will be file type specific..

              * Here I'm considering text file alone..

              *

              */

            FileInputStream fis=null;

            InputStreamReader isr = null;

           

            char[] inputBuffer=null;

            String file_content = null;

           

            try

            {   

                  //As this requires full path of the file...

                  //i.e data/data/package_name/files/your_file_name

                  File sourceFile=

newFile(context.getFilesDir().getPath()

+File.separator+sourceFileName);

                  if(sourceFile.exists())

                  {                      

                        //Probably you will get an exception if its

//a huge content file..

                        //I suggest you to handle content here

//itself, instead of

                        //returning it as return value..

                        inputBuffer=new char[(int) sourceFile.length()];

                 

                        fis=context.openFileInput(sourceFileName);                 

                       

                        isr = new InputStreamReader(fis);                    

                        isr.read(inputBuffer);

                       

                        file_content = new String(inputBuffer);                    

                                                           

                        try

                        {    

                              isr.close();

                              fis.close();

                        }

                        catch (IOException e)

                        {    

                              e.printStackTrace();

                        }

                  }

                 

            }

            catch (Exception e)

            {    

                  e.printStackTrace();

                  file_content=null;

            }

                 

            return file_content;

          }

         

         

public boolean writeToFile(Context context,

byte [] contentToWrite,String destinationFileName)

      {

            FileOutputStream fos=null;

            boolean retValue=false;

            try

            {

                  //Note that your file will be created and stored

                  //under the path: data/data/your_app_package_name/files/

fos=context.openFileOutput(destinationFileName, Context.MODE_PRIVATE);

                 

                  //Note that we are not buffering of contents to write..

                  //So, this will work best for files with less content....

                  fos.write(contentToWrite);

                  //Successfully completed writing..

                  retValue=true;   

                  try

                  {

                        fos.flush();

                        fos.close();

                  }

                  catch (IOException e)

                  {                      

                        e.printStackTrace();

                  }

            }

            catch (Exception e)

            {    

                  //You can catch exceptions specifically for low mem,

                  //file cant be created, and so on..

                  e.printStackTrace();

                  //Failed to write..

                  retValue=false;

            }

                 

            return retValue;       

      }

}

Sample code snippets of how you may use above class is as shown below:

final String TEMP_FILE_NAME="temp.txt";

String contentToWrite="THIS IS THE CONTENT TO WRITE!";

Log.d("DEBUG","Instantiating ReadWriteManager..");

ReadWriteFileManager readWriteFileManager=new ReadWriteFileManager();   

      Log.d("DEBUG","Writing to file..."); 

readWriteFileManager.writeToFile(this,contentToWrite.getBytes(),

TEMP_FILE_NAME );

      Log.d("DEBUG","Reading from file..");

String contentRead= readWriteFileManager.readFromFile(this, TEMP_FILE_NAME);

      Log.d("DEBUG","Content read: "+contentRead);

Once done, you may find your file under DDMS>File Explorer>data/data/package_name/files/

Happy coding :-)

.