Login Application For Android

Last week my friend was stuck for an Android application. That application was to use the remote database (MS SQL Server) for login.

Later I saw the coding of Android, which was Java only. Its much like just another Java framework. So I thought to give a try to help him and even I could learn some Mobile Application programming.

As Android provide flat file data storage or SQlite for data storage, it was quite tough to access the remote database like MSSQL Server, Oracle or MYSql.

Later I found in newtondev that we can execute GET or POST request from the android page and get the output of the requesting page. This lead me to the solution.

I sends the form data from Android application to the Server-side page (JSP, Servlet,ASP or PHP), then those page will compile the required operation for login validation using any database , then it returns “1” if the login is valid else return “0″.

Here are the source codes that will give you Idea for the application.

Application -> res -> layout -> main.xml (interface for Android)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="210dip"
    android:layout_marginTop="10dip"
    android:background="#DDDDDD">
    <TextView
        android:id="@+id/tv_un"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="10pt"
        android:textColor="#444444"
        android:layout_alignParentLeft="true"
        android:layout_marginRight="9dip"
        android:layout_marginTop="20dip"
        android:layout_marginLeft="10dip"
        android:text="User Name:"/>
    <EditText
        android:id="@+id/et_un"
        android:layout_width="150dip"
        android:layout_height="wrap_content"
        android:background="@android:drawable/editbox_background"
        android:layout_toRightOf="@id/tv_un"
        android:layout_alignTop="@id/tv_un"/>
     <TextView
        android:id="@+id/tv_pw"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="10pt"
        android:textColor="#444444"
        android:layout_alignParentLeft="true"
        android:layout_below="@id/tv_un"
        android:layout_marginRight="9dip"
        android:layout_marginTop="15dip"
        android:layout_marginLeft="10dip"
        android:text="Password:"/>
    <EditText
        android:id="@+id/et_pw"
        android:layout_width="150dip"
        android:layout_height="wrap_content"
        android:background="@android:drawable/editbox_background"
        android:layout_toRightOf="@id/tv_pw"
        android:layout_alignTop="@id/tv_pw"
        android:layout_below="@id/et_un"
        android:layout_marginLeft="17dip"
        android:password="true"        />
    <Button
        android:id="@+id/btn_login"
        android:layout_width="100dip"
        android:layout_height="wrap_content"
        android:layout_below="@id/et_pw"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="15dip"
        android:layout_marginLeft="110dip"
        android:text="Login" />
     <TextView
        android:id="@+id/tv_error"
        android:layout_width="fill_parent"
        android:layout_height="40dip"
        android:textSize="7pt"
        android:layout_alignParentLeft="true"
        android:layout_below="@id/btn_login"
        android:layout_marginRight="9dip"
        android:layout_marginTop="15dip"
        android:layout_marginLeft="15dip"
        android:textColor="#AA0000"
        android:text=""/>
</RelativeLayout>

Application -> src -> com.example.login -> LoginLayout.java

package com.example.login;

import java.util.ArrayList;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;

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 LoginLayout extends Activity {
    EditText un,pw;
	TextView error;
    Button ok;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        un=(EditText)findViewById(R.id.et_un);
        pw=(EditText)findViewById(R.id.et_pw);
        ok=(Button)findViewById(R.id.btn_login);
        error=(TextView)findViewById(R.id.tv_error);

        ok.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

            	ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
            	postParameters.add(new BasicNameValuePair("username", un.getText().toString()));
            	postParameters.add(new BasicNameValuePair("password", pw.getText().toString()));

            	String response = null;
            	try {
            	    response = CustomHttpClient.executeHttpPost("<target page url>", postParameters);
            	    String res=response.toString();
            	    res= res.replaceAll("\\s+","");
            	    if(res.equals("1"))
            	    	error.setText("Correct Username or Password");
            	    else
            	    	error.setText("Sorry!! Incorrect Username or Password");
            	} catch (Exception e) {
            		un.setText(e.toString());
            	}

            }
        });
    }
}

Application -> src -> com.example.login ->CustomHttpClient.java (from newtondev)

package com.example.login;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URI;
import java.util.ArrayList;

import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

public class CustomHttpClient {
	/** The time it takes for our client to timeout */
    public static final int HTTP_TIMEOUT = 30 * 1000; // milliseconds

    /** Single instance of our HttpClient */
    private static HttpClient mHttpClient;

    /**
     * Get our single instance of our HttpClient object.
     *
     * @return an HttpClient object with connection parameters set
     */
    private static HttpClient getHttpClient() {
        if (mHttpClient == null) {
            mHttpClient = new DefaultHttpClient();
            final HttpParams params = mHttpClient.getParams();
            HttpConnectionParams.setConnectionTimeout(params, HTTP_TIMEOUT);
            HttpConnectionParams.setSoTimeout(params, HTTP_TIMEOUT);
            ConnManagerParams.setTimeout(params, HTTP_TIMEOUT);
        }
        return mHttpClient;
    }

    /**
     * Performs an HTTP Post request to the specified url with the
     * specified parameters.
     *
     * @param url The web address to post the request to
     * @param postParameters The parameters to send via the request
     * @return The result of the request
     * @throws Exception
     */
    public static String executeHttpPost(String url, ArrayList<NameValuePair> postParameters) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = getHttpClient();
            HttpPost request = new HttpPost(url);
            UrlEncodedFormEntity formEntity = new UrlEncodedFormEntity(postParameters);
            request.setEntity(formEntity);
            HttpResponse response = client.execute(request);
            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");
            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }
            in.close();

            String result = sb.toString();
            return result;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * Performs an HTTP GET request to the specified url.
     *
     * @param url The web address to post the request to
     * @return The result of the request
     * @throws Exception
     */
    public static String executeHttpGet(String url) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = getHttpClient();
            HttpGet request = new HttpGet();
            request.setURI(new URI(url));
            HttpResponse response = client.execute(request);
            in = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));

            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");
            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }
            in.close();

            String result = sb.toString();
            return result;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

Since the application will not be allowed to access the Internet (remote service). So we have to add permission using following line to the AndroidManifest.xml

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

So that the AndroidManifest.xml look like this.

<?xml version="1.0" encoding="utf-8"?>
   <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.example.layout"
           android:versionCode="1"
           android:versionName="1.0">
       <uses-permission android:name="android.permission.INTERNET" />
       <application android:icon="@drawable/icon" android:label="@string/app_name">
       .
       .
       .
       </application>

</manifest>

Then on the server-side we can check login by using password. But here in this example I have use a simple servlet, which check the static login.

package web.com;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author Prashant
 */
@WebServlet(name="AndroidResponse", urlPatterns={"/androidres.do"})
public class AndroidResponse extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        PrintWriter out=response.getWriter();
        String un,pw;
        un=request.getParameter("username");
        pw=request.getParameter("password");
        if(un.equalsIgnoreCase("prashant") && pw.equals("sharma"))
            out.print(1);
        else
            out.print(0);
    }
}

Output :

<?xml version=”1.0″ encoding=”utf-8″?>

<RelativeLayout xmlns:android=”http://schemas.android.com/apk/res/android”

android:layout_width=”fill_parent”

android:layout_height=”210dip”

android:layout_marginTop=”10dip”

android:background=”#DDDDDD”>

<TextView

android:id=”@+id/tv_un”

android:layout_width=”wrap_content”

android:layout_height=”wrap_content”

android:textSize=”10pt”

android:textColor=”#444444″

android:layout_alignParentLeft=”true”

android:layout_marginRight=”9dip”

android:layout_marginTop=”20dip”

android:layout_marginLeft=”10dip”

android:text=”User Name:”/>

<EditText

android:id=”@+id/et_un”

android:layout_width=”150dip”

android:layout_height=”wrap_content”

android:background=”@android:drawable/editbox_background”

android:layout_toRightOf=”@id/tv_un”

android:layout_alignTop=”@id/tv_un”/>

<TextView

android:id=”@+id/tv_pw”

android:layout_width=”wrap_content”

android:layout_height=”wrap_content”

android:textSize=”10pt”

android:textColor=”#444444″

android:layout_alignParentLeft=”true”

android:layout_below=”@id/tv_un”

android:layout_marginRight=”9dip”

android:layout_marginTop=”15dip”

android:layout_marginLeft=”10dip”

android:text=”Password:”/>

<EditText

android:id=”@+id/et_pw”

android:layout_width=”150dip”

android:layout_height=”wrap_content”

android:background=”@android:drawable/editbox_background”

android:layout_toRightOf=”@id/tv_pw”

android:layout_alignTop=”@id/tv_pw”

android:layout_below=”@id/et_un”

android:layout_marginLeft=”17dip”

android:password=”true”        />

<Button

android:id=”@+id/btn_login”

android:layout_width=”100dip”

android:layout_height=”wrap_content”

android:layout_below=”@id/et_pw”

android:layout_alignParentLeft=”true”

android:layout_marginTop=”15dip”

android:layout_marginLeft=”110dip”

android:text=”Login” />

<TextView

android:id=”@+id/tv_error”

android:layout_width=”fill_parent”

android:layout_height=”40dip”

android:textSize=”7pt”

android:layout_alignParentLeft=”true”

android:layout_below=”@id/btn_login”

android:layout_marginRight=”9dip”

android:layout_marginTop=”15dip”

android:layout_marginLeft=”15dip”

android:textColor=”#AA0000″

android:text=”"/>

</RelativeLayout>