HTTP post from an android application using URLConnection

A simple android application which makes a HTTP POST request to a servlet.

The comments in the source are quite self explanatory. Leave a feedback for any clarifications.


SDK version used : 2.3.3

The project structure :

1. AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.httpapp"

    android:versionCode="1"

    android:versionName="1.0" >



    <uses-sdk android:minSdkVersion="10" />

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



    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name" >

        <activity

            android:name=".HttpAppActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />



                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>



</manifest>

We have to add the permission for internet access.

2. main.xml

This is your layout for your main activity

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >





    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="@string/firstname"

        android:textAppearance="?android:attr/textAppearanceLarge" />







    <EditText

        android:id="@+id/fnameID"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:ems="10" />





    <TextView

        android:id="@+id/textView4"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="@string/lastname"

        android:textAppearance="?android:attr/textAppearanceLarge" />





    <EditText

        android:id="@+id/lnameID"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:ems="10" >



        <requestFocus />

    </EditText>



    <Button

        android:id="@+id/submitID"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="@string/submit" />







    <TextView

        android:id="@+id/resultID"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_weight="0.41" />



</LinearLayout>

3. strings.xml

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <string name="hello">Hello World</string>

    <string name="app_name">HTTP app</string>

    <string name="submit">submit</string>

    <string name="firstname">First name</string>

    <string name="lastname">Last name</string>

</resources>

4. HttpAppActivity.java

package com.httpapp;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

public class HttpAppActivity extends Activity {

    

    @Override

    public void onCreate(Bundle savedInstanceState) 

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        

        // Get the submit button and attach a listener to its click event

        Button submitBtn = (Button)findViewById(R.id.submitID);

        submitBtn.setOnClickListener(new Button.OnClickListener(){

            public void onClick(View v)

            {

           

            EditText fnameText = (EditText)findViewById(R.id.fnameID); // Get a handle to the input box for first name

            EditText lnameText = (EditText)findViewById(R.id.lnameID); // Get a handle to the input box for last name

           

           

           

            //Make a call to our helper class

            String result = ServletInterface.executeHttpRequest(fnameText.getText().toString(), lnameText.getText().toString());

           

           

           

            TextView resultView = (TextView) findViewById(R.id.resultID); // Get the textView where we will display the result

            resultView.setText(result); //set the returned result to the view

            }

        });

            

    }

}

5. ServletInterface.java

package com.httpapp;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.UnsupportedEncodingException;

import java.net.URL;

import java.net.URLConnection;

import java.net.URLEncoder;

import android.util.Log;

/**

*  This class is the interface for making calls to a Servlet in a remote server

*

*/

public class ServletInterface 

{

public static final String SERVER_URL = "http://10.0.2.2:8080"; // The server(Servlet) which will process the request. Note 10.0.2.2 is the localhost IP for emulator

    public static final String CHAR_SET = "UTF-8"; // Encoding used for the parameters

  

    

    public static String executeHttpRequest(String fname, String lname) 

    {

   

    OutputStream output = null;

    String response = ""; 

   

    try 

    {

    Log.i("HTTP :", "Preparing data");

    // ------------------------------------------------------START: PREPARE CONNETION AND REQUEST ------------------------------- //

   

    // Prepare the data string  [ firstName=JOHN&lastName=SMITH ]

String data = URLEncoder.encode("firstName", CHAR_SET) + "=" + URLEncoder.encode(fname, CHAR_SET);

data += "&" + URLEncoder.encode("lastName", CHAR_SET) + "=" + URLEncoder.encode(lname, CHAR_SET);

URLConnection connection = new URL(SERVER_URL).openConnection(); // Create a connection to server using URL

connection.setDoOutput(true); // This means POST method to be used

connection.setRequestProperty("Accept-Charset", CHAR_SET); //For servers to know what encoding is used for the parameters

connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=" + CHAR_SET);

output = null; 

output = connection.getOutputStream(); //open a Output stream from the connection for posting data

   output.write(data.getBytes(CHAR_SET)); //Post data

   

   //------------------------------------------------------ END: PREPARE CONNETION AND REQUEST --------------------------------- //

   

   

   Log.i("HTTP :", "sending data");

   InputStream responseStream = connection.getInputStream(); //This is when the request is actually fired

   

   

   

 //------------------------------------------------------ START: READ RESPONSE ------------------------------------------------ //

   

   Log.i("HTTP :", "Reading response");

            BufferedReader rd = new BufferedReader(new InputStreamReader(responseStream,CHAR_SET)); // Connect a BufferReader to the inputStream

            String line = null;

            

            while ((line = rd.readLine()) != null) // Read the response line-by-line from the bufferedReader

            {

               response += line;

            }

   

 //------------------------------------------------------ END: READ RESPONSE ------------------------------------------------- //

   

   

}

    catch (UnsupportedEncodingException e) 

    {

e.printStackTrace();

}

    catch(IOException io)

    {

    //Log and check exp

    }

    finally

    {

    if (output != null) try { output.close(); } catch (IOException ignoreIO) {}

    }

   

   

return response;

   

    }

}

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At the servlet end you can read the parameters using :

String fname = (String) request.getParameter("firstName");

String lname = (String) request.getParameter("lastName");