Hey guys im new to java and could anyone show me how to make a simple login system? where the username and passwords are store in variables ? or if its not to much trouble using a database i have no idea how to do this .

the reason why i have asked for this is because it would show me how an "if" statement also could you maybe have it where when the user logs in it shows a message "Hello and welcome user" then goes to the next window (where you put the rest of the app) else "you have failed to login")

if this seems weird lol its because im a VB coder and getting grips with a new code is strange haha

thankyou guys i will really appreciate this

Okay.. lets start with the main app which calls the login screen..

The Main activity basically starts the Login activity and waits for the result.
If the Login activity returns and the login was correct startup() is called and
the textview shows which user logged in.

Main Activity




Now the Login Activity..

Login Activity


here is the main layout..

main.xml


the manifest file...

AndroidManifest.xml



and last but not least the php script on the server....

login.php

Code: Select all

<?php
    unset($_GET);
   
    if( isset($_POST['username']) && isset($_POST['password']) ) {
   
        echo '<?xml version="1.0"?>'."\n";
        echo "<login>\n";
   
        if (!@mysql_connect('host', 'user', 'pass')) { error(1); }
        if (!mysql_select_db('database')) { error(2); }
   
        if(get_magic_quotes_gpc()) {
            $login = stripslashes($_POST['username']);
            $pass  = stripslashes($_POST['password']);
        } else {
            $login = $_POST['username'];
            $pass  = $_POST['password'];
        }
   
        unset($_POST);
       
        $kid = login($login, $pass);
        if($kid == -1) {
            error(3);
        } else {
            printf('    <user id="%d"/>'."\n",$kid);
        }
               
        echo "</login>";
    }

    function error($ec) {
        printf('    <error value="%d"/>'."\n".'</login>',$ec);
        die();
    }

    function login($login, $pass) {
        $select = "SELECT user_id FROM auth_table ";
        $where = "WHERE username = '%s' AND password = '%s'";
        $fixedlogin = mysql_real_escape_string($login);
        $fixedpass  = mysql_real_escape_string($pass);
        $query = sprintf($select.$where, $fixedlogin, $fixedpass);
        $result = mysql_query($query);
        if(mysql_num_rows($result) != 1) { return -1; }   
        $row = mysql_fetch_row($result);
        return $row[0];
    }
?>


Try Username: test and Password: test

Greets
Padde

--- Edited ---
Reason: added missing quote in php code

Thx @ myshoes for pointing that out

Sorry forgot the MySQL dump

Code: Select all

-- phpMyAdmin SQL Dump
-- version 2.6.4-pl4
-- http://www.phpmyadmin.net
--
-- Host: localhost
-- Erstellungszeit: 14. April 2009 um 22:12
-- Server Version: 4.1.22
-- PHP-Version: 5.2.9
--
-- Datenbank: `paddesite`
--

-- --------------------------------------------------------

--
-- Tabellenstruktur für Tabelle `auth_table`
--

CREATE TABLE IF NOT EXISTS `auth_table` (
  `user_id` int(10) unsigned NOT NULL auto_increment,
  `username` varchar(20) NOT NULL default '',
  `password` varchar(32) NOT NULL default '',
  PRIMARY KEY  (`user_id`),
  UNIQUE KEY `username` (`username`)
) TYPE=MyISAM AUTO_INCREMENT=2 AUTO_INCREMENT=2 ;

--
-- Daten für Tabelle `auth_table`
--

INSERT INTO `auth_table` VALUES (1, 'test', '098f6bcd4621d373cade4e832627b4f6');


Greets
Padde

Thankyou dude this has helped allot thanks :D:D

hey dude ya know your PHP script where do i enter the details :S sorry php n00b thanks tho dude

Hi padde,

This code is very helpful .
But, How should I proceed, If I put the java servlet(Login.java) or JSP(login.jsp) instead of login.php?

Thanks in advance..

Here on request a simple Login that uses your Google Account

Main.java


Login.java


main.xml


AndroidManifest.xml



No mysql db or php script needed.. just use your google account login.
I hope i understand the request correct and this is the right solution

I should mention that this is not a rock stable login method.. if google
change their login site this no longer works.

And by the way.. in case you wonder.. google sends wrong content-length thats
the reason for this hack like method instead of a clean check etc.

Greets
Padde

Great, thanks for your tutorial.

Thanks for the update dude really helped

Very great tutorial, thanks a lot padde.

padde wrote:Okay.. lets start with the main app which calls the login screen..

The Main activity basically starts the Login activity and waits for the result.
If the Login activity returns and the login was correct startup() is called and
the textview shows which user logged in.

Main Activity

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Syntax: [ Download ] [ Show ]

Using java Syntax Highlighting

1. package de.demo.main;
2.  
3. import android.app.Activity;
4. import android.content.Intent;
5. import android.os.Bundle;
6. import android.widget.TextView;
7. import de.demo.login.Login;
8.  
9. public class Main extends Activity {
10.     private TextView tv;
11.    
12.     public void onCreate(Bundle icicle) {
13.         super.onCreate(icicle);
14.  
15.         startActivityForResult(new Intent(Main.this, Login.class), 1);
16.        
17.         tv = new TextView(this);
18.         setContentView(tv);
19.     }
20.    
21.     private void startup(Intent i) {
22.         int user = i.getIntExtra("userid",-1);
23.         tv.setText("UserID: "+String.valueOf(user)+" logged in");
24.     }
25.    
26.     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
27.         if(requestCode == 1 && resultCode == RESULT_CANCELED)
28.             finish();
29.         else
30.             startup(data);
31.     }
32. }
33.  

Parsed in 0.039 seconds, using GeSHi 1.0.8.4

Now the Login Activity..

Login Activity

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Using java Syntax Highlighting

1. package de.demo.login;
2.  
3. import java.io.IOException;
4. import java.io.InputStream;
5. import java.security.MessageDigest;
6. import java.security.NoSuchAlgorithmException;
7. import java.util.ArrayList;
8. import java.util.List;
9.  
10. import javax.xml.parsers.ParserConfigurationException;
11. import javax.xml.parsers.SAXParser;
12. import javax.xml.parsers.SAXParserFactory;
13.  
14. import org.apache.http.HttpEntity;
15. import org.apache.http.HttpResponse;
16. import org.apache.http.NameValuePair;
17. import org.apache.http.client.entity.UrlEncodedFormEntity;
18. import org.apache.http.client.methods.HttpPost;
19. import org.apache.http.impl.client.DefaultHttpClient;
20. import org.apache.http.message.BasicNameValuePair;
21. import org.apache.http.params.HttpConnectionParams;
22. import org.apache.http.protocol.HTTP;
23. import org.xml.sax.Attributes;
24. import org.xml.sax.InputSource;
25. import org.xml.sax.SAXException;
26. import org.xml.sax.XMLReader;
27. import org.xml.sax.helpers.DefaultHandler;
28.  
29. import android.app.Activity;
30. import android.app.AlertDialog;
31. import android.app.ProgressDialog;
32. import android.content.Intent;
33. import android.os.Bundle;
34. import android.os.Looper;
35. import android.view.View;
36. import android.widget.Button;
37. import android.widget.EditText;
38. import de.demo.main.R;
39.  
40. public class Login extends Activity {
41.     private static final String UPDATE_URL = "http://paddesite.pa.ohost.de/login.php";
42.     public ProgressDialog progressDialog;
43.     private EditText UserEditText;
44.     private EditText PassEditText;
45.    
46.     public void onCreate(Bundle savedInstanceState) {
47.         super.onCreate(savedInstanceState);
48.         setContentView(R.layout.main);
49.  
50.         progressDialog = new ProgressDialog(this);
51.         progressDialog.setMessage("Please wait...");
52.         progressDialog.setIndeterminate(true);
53.         progressDialog.setCancelable(false);
54.        
55.         UserEditText = (EditText) findViewById(R.id.username);
56.         PassEditText = (EditText) findViewById(R.id.password);
57.        
58.         Button button = (Button) findViewById(R.id.okbutton);
59.         button.setOnClickListener(new View.OnClickListener() {
60.             public void onClick(View v) {
61.                 int usersize = UserEditText.getText().length();
62.                 int passsize = PassEditText.getText().length();
63.                 if(usersize > 0 && passsize > 0) {
64.                     progressDialog.show();
65.                     String user = UserEditText.getText().toString();
66.                     String pass = PassEditText.getText().toString();
67.                     doLogin(user, pass);
68.                 } else createDialog("Error","Please enter Username and Password");
69.             }
70.         });
71.        
72.         button = (Button) findViewById(R.id.cancelbutton);
73.         button.setOnClickListener(new View.OnClickListener() {
74.             public void onClick(View v) { quit(false, null); }
75.         });
76.     }
77.  
78.     private void quit(boolean success, Intent i) {
79.         setResult( (success) ? -1:0, i);
80.         finish();
81.     }
82.    
83.     private void createDialog(String title, String text) {
84.         AlertDialog ad = new AlertDialog.Builder(this)
85.         .setPositiveButton("Ok", null)
86.         .setTitle(title)
87.         .setMessage(text)
88.         .create();
89.         ad.show();
90.     }
91.    
92.     private void doLogin(final String login, final String pass) {
93.         final String pw = md5(pass);
94.         Thread t = new Thread() {
95.             public void run() {
96.                 Looper.prepare();
97.                 DefaultHttpClient client = new DefaultHttpClient();
98.                 HttpConnectionParams.setConnectionTimeout(client.getParams(), 15000);                
99.                 HttpResponse response;
100.                 HttpEntity entity;        
101.                 try {
102.                     HttpPost post = new HttpPost(UPDATE_URL);
103.                     List <NameValuePair> nvps = new ArrayList <NameValuePair>();
104.                     nvps.add(new BasicNameValuePair("username", login));
105.                     nvps.add(new BasicNameValuePair("password", pw));
106.                     post.setHeader("Content-Type", "application/x-www-form-urlencoded");
107.                     post.setEntity(new UrlEncodedFormEntity(nvps, HTTP.UTF_8));
108.                     response = client.execute(post);
109.                     entity = response.getEntity();
110.                     InputStream is = entity.getContent();
111.                     read(is);
112.                     is.close();
113.                     if (entity != null) entity.consumeContent();
114.                 } catch (Exception e) {
115.                     progressDialog.dismiss();
116.                     createDialog("Error", "Couldn't establish a connection");
117.                 }
118.                 Looper.loop();                
119.             }
120.         };
121.         t.start();
122.     }
123.    
124.     private void read(InputStream in) {
125.         SAXParserFactory spf = SAXParserFactory.newInstance();
126.         SAXParser sp;
127.         try {
128.             sp = spf.newSAXParser();
129.             XMLReader xr = sp.getXMLReader();
130.             LoginContentHandler uch = new LoginContentHandler();
131.             xr.setContentHandler(uch);
132.             xr.parse(new InputSource(in));
133.         } catch (ParserConfigurationException e) {
134.         } catch (SAXException e) {
135.         } catch (IOException e) {}
136.     }    
137.    
138.     private String md5(String in) {
139.         MessageDigest digest;
140.         try {
141.             digest = MessageDigest.getInstance("MD5");
142.             digest.reset();        
143.             digest.update(in.getBytes());
144.             byte[] a = digest.digest();
145.             int len = a.length;
146.             StringBuilder sb = new StringBuilder(len << 1);
147.             for (int i = 0; i < len; i++) {
148.                 sb.append(Character.forDigit((a[i] & 0xf0) >> 4, 16));
149.                 sb.append(Character.forDigit(a[i] & 0x0f, 16));
150.             }
151.             return sb.toString();
152.         } catch (NoSuchAlgorithmException e) { e.printStackTrace(); }
153.         return null;
154.     }
155.    
156.     private class LoginContentHandler extends DefaultHandler {
157.         private boolean in_loginTag = false;
158.         private int userID;
159.         private boolean error_occured = false;
160.  
161.         public void startElement(String n, String l, String q, Attributes a)
162.             throws SAXException
163.         {
164.             if(l == "login") in_loginTag = true;  
165.             if(l == "error") {
166.                 progressDialog.dismiss();
167.                 if(Integer.parseInt(a.getValue("value")) == 1)
168.                     createDialog("Error", "Couldn't connect to Database");
169.                 if(Integer.parseInt(a.getValue("value")) == 2)
170.                     createDialog("Error", "Error in Database: Table missing");
171.                 if(Integer.parseInt(a.getValue("value")) == 3)
172.                     createDialog("Error", "Invalid username and/or password");
173.                 error_occured = true;
174.             }
175.             if(l == "user" && in_loginTag && a.getValue("id") != "")            
176.                 userID = Integer.parseInt(a.getValue("id"));
177.         }
178.          
179.         public void endElement(String n, String l, String q) throws SAXException {
180.             if(l == "login") {
181.                 in_loginTag = false;
182.                 if(!error_occured) {
183.                     progressDialog.dismiss();
184.                     Intent i = new Intent();
185.                     i.putExtra("userid", userID);
186.                     quit(true,i);
187.                 }
188.             }
189.         }
190.          
191.         public void characters(char ch[], int start, int length) { }
192.         public void startDocument() throws SAXException { }
193.         public void endDocument() throws SAXException { }
194.     }    
195. }
196.  

Parsed in 0.070 seconds, using GeSHi 1.0.8.4

here is the main layout..

main.xml

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Using xml Syntax Highlighting

1. <?xml version="1.0" encoding="utf-8"?>
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
3.    android:orientation="vertical"
4.    android:layout_width="fill_parent"
5.    android:layout_height="fill_parent"
6.    android:gravity="center">
7.    
8.         <TextView  
9.             android:layout_width="fill_parent"
10.             android:layout_height="wrap_content"
11.             android:text="Username"
12.         />
13.         <EditText
14.             android:id="@+id/username"
15.             android:layout_width="fill_parent"
16.             android:layout_height="wrap_content"
17.        android:singleLine="true"
18.        android:fadingEdge="horizontal"
19.        android:layout_marginBottom="20dip"/>
20.         <TextView
21.        android:layout_width="fill_parent"
22.        android:layout_height="wrap_content"
23.        android:text="Password"
24.         />
25.         <EditText
26.        android:id="@+id/password"
27.        android:layout_width="fill_parent"
28.        android:layout_height="wrap_content"
29.        android:password="true"
30.        android:singleLine="true"
31.         android:fadingEdge="horizontal"
32.         />
33.         <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
34.        android:orientation="vertical"
35.        android:layout_width="fill_parent"
36.        android:layout_height="fill_parent"
37.        android:gravity="bottom">
38.  
39.         <Button
40.            android:id="@+id/okbutton"
41.            android:layout_width="fill_parent"
42.            android:layout_height="wrap_content"
43.            android:text="Login"
44.        />    
45.         <Button
46.            android:id="@+id/cancelbutton"
47.            android:layout_width="fill_parent"
48.            android:layout_height="wrap_content"
49.            android:text="Cancel"
50.        />
51.     </LinearLayout>      
52. </LinearLayout>
53.  

Parsed in 0.006 seconds, using GeSHi 1.0.8.4

the manifest file...

AndroidManifest.xml

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Using java Syntax Highlighting

1. <?xml version="1.0" encoding="utf-8"?>
2. <manifest xmlns:android="http://schemas.android.com/apk/res/android"
3.       package="de.demo.main"
4.       android:versionCode="1"
5.       android:versionName="1.0.0">
6.     <application android:icon="@drawable/icon" android:label="LoginDemo">
7.         <activity android:name="de.demo.main.Main" android:label="LoginDemo">
8.             <intent-filter>
9.                 <action android:name="android.intent.action.MAIN" />
10.                 <category android:name="android.intent.category.LAUNCHER" />
11.             </intent-filter>
12.         </activity>
13.         <activity android:name="de.demo.login.Login" android:label="LoginDemo">
14.             <intent-filter>
15.                 <action android:name="android.intent.action.VIEW" />
16.                 <category android:name="android.intent.category.DEFAULT" />
17.             </intent-filter>
18.         </activity>        
19.     </application>
20. <uses-permission android:name="android.permission.INTERNET"></uses-permission>    
21. </manifest>
22.  

Parsed in 0.039 seconds, using GeSHi 1.0.8.4

and last but not least the php script on the server....

login.php

Code: Select all

<?php
    unset($_GET);
   
    if( isset($_POST['username']) && isset($_POST['password']) ) {
   
        echo '<?xml version="1.0"?>'."\n";
        echo "<login>\n";
   
        if (!@mysql_connect(host', 'user', 'pass')) { error(1); }
        if (!mysql_select_db('database')) { error(2); }
   
        if(get_magic_quotes_gpc()) {
            $login = stripslashes($_POST['username']);
            $pass  = stripslashes($_POST['password']);
        } else {
            $login = $_POST['username'];
            $pass  = $_POST['password'];
        }
   
        unset($_POST);
       
        $kid = login($login, $pass);
        if($kid == -1) {
            error(3);
        } else {
            printf('    <user id="%d"/>'."\n",$kid);
        }
               
        echo "</login>";
    }

    function error($ec) {
        printf('    <error value="%d"/>'."\n".'</login>',$ec);
        die();
    }

    function login($login, $pass) {
        $select = "SELECT user_id FROM auth_table ";
        $where = "WHERE username = '%s' AND password = '%s'";
        $fixedlogin = mysql_real_escape_string($login);
        $fixedpass  = mysql_real_escape_string($pass);
        $query = sprintf($select.$where, $fixedlogin, $fixedpass);
        $result = mysql_query($query);
        if(mysql_num_rows($result) != 1) { return -1; }   
        $row = mysql_fetch_row($result);
        return $row[0];
    }
?>


Try Username: test and Password: test

Greets
Padde

FYI, I don't know if anyone else had an issue with the PHP code but the following line should replace the authors as it was missing a quote around "host":

Thx for pointing that out myshoes.
I edited the version and added the missing quote.
I guess the failure wasnt discovered before because
most people use the version with the google account.

hi padde

can u post a small sample program,in which i can send parameters to my server's db through android?
actually wat i want in my application is to send latitude/lognitude and username from android to my server's database...


thanks and regards
hopes for a quick reply

Hi padde,

I think it works no more

Hi. I am new to android. Quite noob. But when i try to enter a new user_id and password, it throws up an error stating that invalid user and password. From what i see in the database, the password seems to be encrypted somehow, could you enlighten me as to the method to go about this issue.