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");
