android session mgmt

written by http://www.androidhive.info/2012/08/android-session-management-using-shared-preferences/

Initialization

Application shared preferences can be fetched using getSharedPreferences() method.You also need an editor to edit and save the changes in shared preferences. The following code can be used to get application shared preferences.

SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode Editor editor = pref.edit();

Storing Data

You can save data into shared preferences using editor. All the primitive data types like booleans, floats, ints, longs, and strings are supported. Call editor.commit() in order to save changes to shared preferences.

editor.putBoolean("key_name", true); // Storing boolean - true/false editor.putString("key_name", "string value"); // Storing string editor.putInt("key_name", "int value"); // Storing integer editor.putFloat("key_name", "float value"); // Storing float editor.putLong("key_name", "long value"); // Storing long   editor.commit(); // commit changes

Retrieving Data

Data can be retrived from saved preferences by calling getString() (For string) method. Remember this method should be called on Shared Preferences not on Editor.

// returns stored preference value // If value is not present return second param value - In this case null pref.getString("key_name", null); // getting String pref.getInt("key_name", null); // getting Integer pref.getFloat("key_name", null); // getting Float pref.getLong("key_name", null); // getting Long pref.getBoolean("key_name", null); // getting boolean

Clearing / Deleting Data

If you want to delete from shared preferences you can call remove(“key_name”) to delete that particular value. If you want to delete all the data, call clear()

editor.remove("name"); // will delete key name editor.remove("email"); // will delete key email   editor.commit(); // commit changes

Following will clear all the data from shared preferences

editor.clear(); editor.commit(); // commit changes

The following is a simple tutorial which will have a login form and a dashboard screen. At first user will login using login details and once he successfully logged in his credentials (name, email) will be stored in shared preferences.

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User Session Management using Shared Preferences

1. Create a new project in Eclipse IDE File ⇒ New ⇒ Android Application Project and fill all the required details
2. I am adding alert dialog manager class to show alert messages while validating the login form. Create a new class and name it as AlertDialogManager.java and paste the following code.

AlertDialogManager.java

package com.androidhive.sessions;     import android.app.AlertDialog; import android.content.Context; import android.content.DialogInterface;    public class AlertDialogManager {     /**      * Function to display simple Alert Dialog      * @param context - application context      * @param title - alert dialog title      * @param message - alert message      * @param status - success/failure (used to set icon)      *               - pass null if you don't want icon      * */     public void showAlertDialog(Context context, String title, String message,             Boolean status) {         AlertDialog alertDialog = new AlertDialog.Builder(context).create();            // Setting Dialog Title         alertDialog.setTitle(title);            // Setting Dialog Message         alertDialog.setMessage(message);            if(status != null)             // Setting alert dialog icon             alertDialog.setIcon((status) ? R.drawable.success : R.drawable.fail);            // Setting OK Button         alertDialog.setButton("OK", new DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialog, int which) {             }         });            // Showing Alert Message         alertDialog.show();     } }

3. I am writing all session related functions in one class to make them available in all activities. Create a new class named SessionManagement.java and add following lines of code

SessionManagement.java

package com.androidhive.sessions;   import java.util.HashMap;   import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.content.SharedPreferences.Editor;   public class SessionManager {     // Shared Preferences     SharedPreferences pref;           // Editor for Shared preferences     Editor editor;           // Context     Context _context;           // Shared pref mode     int PRIVATE_MODE = 0;           // Sharedpref file name     private static final String PREF_NAME = "AndroidHivePref";           // All Shared Preferences Keys     private static final String IS_LOGIN = "IsLoggedIn";           // User name (make variable public to access from outside)     public static final String KEY_NAME = "name";           // Email address (make variable public to access from outside)     public static final String KEY_EMAIL = "email";           // Constructor     public SessionManager(Context context){         this._context = context;         pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);         editor = pref.edit();     }

4. In this example i am storing login status, name, email in shared preferences, so i added a function called createLoginSession(String name, String email) to SessionManagement class. Add the following function to SessionManagement.java.

> This function simply stores login status(true), name, email in shared preferences.

/**      * Create login session      * */     public void createLoginSession(String name, String email){         // Storing login value as TRUE         editor.putBoolean(IS_LOGIN, true);                   // Storing name in pref         editor.putString(KEY_NAME, name);                   // Storing email in pref         editor.putString(KEY_EMAIL, email);                   // commit changes         editor.commit();     }

5.In order to get the stored preferences data, I added a function called getUserDetails() with the following code.

> The following function will read shared preferences and returns user data in HashMap

/**      * Get stored session data      * */     public HashMap<String, String> getUserDetails(){         HashMap<String, String> user = new HashMap<String, String>();         // user name         user.put(KEY_NAME, pref.getString(KEY_NAME, null));                   // user email id         user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));                   // return user         return user;     }

6. To check whether user logged in or not i added a function checkLogin() which you can call in all Activities to check user login status.

> This function simply check user login status from shared preferences and if user is not login it will redirect user to LoginActivity

/**      * Check login method wil check user login status      * If false it will redirect user to login page      * Else won't do anything      * */     public void checkLogin(){         // Check login status         if(!this.isLoggedIn()){             // user is not logged in redirect him to Login Activity             Intent i = new Intent(_context, LoginActivity.class);             // Closing all the Activities             i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);                           // Add new Flag to start new Activity             i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                           // Staring Login Activity             _context.startActivity(i);         }               }

7. Add a function called logoutUser() to clear all the data from shared preferences. Call this function when you want to logout the user.

> This function clears all session data and redirect the user to LoginActivity

/**      * Clear session details      * */     public void logoutUser(){         // Clearing all data from Shared Preferences         editor.clear();         editor.commit();                   // After logout redirect user to Loing Activity         Intent i = new Intent(_context, LoginActivity.class);         // Closing all the Activities         i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);                   // Add new Flag to start new Activity         i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                   // Staring Login Activity         _context.startActivity(i);     }

Final Code

SessionManagement.java

package com.androidhive.sessions;   import java.util.HashMap;   import android.content.Context; import android.content.Intent; import android.content.SharedPreferences; import android.content.SharedPreferences.Editor;   public class SessionManager {     // Shared Preferences     SharedPreferences pref;           // Editor for Shared preferences     Editor editor;           // Context     Context _context;           // Shared pref mode     int PRIVATE_MODE = 0;           // Sharedpref file name     private static final String PREF_NAME = "AndroidHivePref";           // All Shared Preferences Keys     private static final String IS_LOGIN = "IsLoggedIn";           // User name (make variable public to access from outside)     public static final String KEY_NAME = "name";           // Email address (make variable public to access from outside)     public static final String KEY_EMAIL = "email";           // Constructor     public SessionManager(Context context){         this._context = context;         pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);         editor = pref.edit();     }           /**      * Create login session      * */     public void createLoginSession(String name, String email){         // Storing login value as TRUE         editor.putBoolean(IS_LOGIN, true);                   // Storing name in pref         editor.putString(KEY_NAME, name);                   // Storing email in pref         editor.putString(KEY_EMAIL, email);                   // commit changes         editor.commit();     }             /**      * Check login method wil check user login status      * If false it will redirect user to login page      * Else won't do anything      * */     public void checkLogin(){         // Check login status         if(!this.isLoggedIn()){             // user is not logged in redirect him to Login Activity             Intent i = new Intent(_context, LoginActivity.class);             // Closing all the Activities             i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);                           // Add new Flag to start new Activity             i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                           // Staring Login Activity             _context.startActivity(i);         }               }                       /**      * Get stored session data      * */     public HashMap<String, String> getUserDetails(){         HashMap<String, String> user = new HashMap<String, String>();         // user name         user.put(KEY_NAME, pref.getString(KEY_NAME, null));                   // user email id         user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));                   // return user         return user;     }           /**      * Clear session details      * */     public void logoutUser(){         // Clearing all data from Shared Preferences         editor.clear();         editor.commit();                   // After logout redirect user to Loing Activity         Intent i = new Intent(_context, LoginActivity.class);         // Closing all the Activities         i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);                   // Add new Flag to start new Activity         i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);                   // Staring Login Activity         _context.startActivity(i);     }           /**      * Quick check for login      * **/     // Get Login State     public boolean isLoggedIn(){         return pref.getBoolean(IS_LOGIN, false);     } }

8. Until now we are done creating Session Management class and now we are going to learn how to use this class in your application. For this create a simple login form asking username, password.

Create a layout xml file and a class to create login form. Name the xml file as activity_login.xml and class name as LoginActivity.java

activity_login.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical"     android:padding="10dip">       <!-- Email Label -->     <TextView         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Username (Enter 'test')"         android:singleLine="true"         android:layout_marginBottom="5dip"/>           <!-- Email input text -->     <EditText android:id="@+id/txtUsername"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:layout_marginBottom="10dip"/>           <!-- Password Label -->     <TextView         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Password (Enter 'test')"         android:layout_marginBottom="5dip"/>           <!-- Password input text -->     <EditText android:id="@+id/txtPassword"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:layout_marginBottom="20dip"         android:password="true"         android:singleLine="true"/>           <!-- Login button -->     <Button android:id="@+id/btnLogin"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Login"/>   </LinearLayout>

For testing purpose i am checking username, password as test, test.

Once the user enters correct login details a session will be created by callingsession.createLoginSession(“Android Hive”, “anroidhive@gmail.com”) and user is redirected toMainActivity.

LoginActivity.java

package com.androidhive.sessions;   import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast;   public class LoginActivity extends Activity {           // Email, password edittext     EditText txtUsername, txtPassword;           // login button     Button btnLogin;           // Alert Dialog Manager     AlertDialogManager alert = new AlertDialogManager();           // Session Manager Class     SessionManager session;       @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_login);                   // Session Manager         session = new SessionManager(getApplicationContext());                                  // Email, Password input text         txtUsername = (EditText) findViewById(R.id.txtUsername);         txtPassword = (EditText) findViewById(R.id.txtPassword);                   Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();                             // Login button         btnLogin = (Button) findViewById(R.id.btnLogin);                             // Login button click event         btnLogin.setOnClickListener(new View.OnClickListener() {                           @Override             public void onClick(View arg0) {                 // Get username, password from EditText                 String username = txtUsername.getText().toString();                 String password = txtPassword.getText().toString();                                   // Check if username, password is filled                                if(username.trim().length() > 0 && password.trim().length() > 0){                     // For testing puspose username, password is checked with sample data                     // username = test                     // password = test                     if(username.equals("test") && password.equals("test")){                                                   // Creating user login session                         // For testing i am stroing name, email as follow                         // Use user real data                         session.createLoginSession("Android Hive", "anroidhive@gmail.com");                                                   // Staring MainActivity                         Intent i = new Intent(getApplicationContext(), MainActivity.class);                         startActivity(i);                         finish();                                               }else{                         // username / password doesn't match                         alert.showAlertDialog(LoginActivity.this, "Login failed..", "Username/Password is incorrect", false);                     }                               }else{                     // user didn't entered username or password                     // Show alert asking him to enter the details                     alert.showAlertDialog(LoginActivity.this, "Login failed..", "Please enter username and password", false);                 }                               }         });     }        }

9. After user redirected to MainActivity, I am getting stored session data by calling getUserDetails() and displayed in textviews.

> session.checkLogin() is called to check user login status. Here if user is not login he will be redirected to LoginActivity.java
> If user is logged in, user details are fetched by calling session.getUserDetails() and displayed in textviews.
> Also I have logout button which invokes a function session.logoutUser() to clear the session data.
Layout code for activity_main.xml

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="vertical"     android:padding="10dip">           <!-- Name Label -->     <TextView         android:id="@+id/lblName"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:singleLine="true"         android:layout_marginTop="40dip"         android:layout_marginBottom="10dip"/>       <!-- Email Label -->     <TextView         android:id="@+id/lblEmail"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:singleLine="true"         android:layout_marginBottom="40dip"/>           <!-- Button to show session data -->     <Button android:id="@+id/btnLogout"         android:layout_width="fill_parent"         android:layout_height="wrap_content"         android:text="Logout"/> </LinearLayout>

Code for MainActivity.java

package com.androidhive.sessions;   import java.util.HashMap;   import android.app.Activity; import android.os.Bundle; import android.text.Html; import android.view.View; import android.widget.Button; import android.widget.TextView; import android.widget.Toast;   public class MainActivity extends Activity {           // Alert Dialog Manager     AlertDialogManager alert = new AlertDialogManager();           // Session Manager Class     SessionManager session;           // Button Logout     Button btnLogout;       @Override     public void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);                   // Session class instance         session = new SessionManager(getApplicationContext());                   TextView lblName = (TextView) findViewById(R.id.lblName);         TextView lblEmail = (TextView) findViewById(R.id.lblEmail);                   // Button logout         btnLogout = (Button) findViewById(R.id.btnLogout);                   Toast.makeText(getApplicationContext(), "User Login Status: " + session.isLoggedIn(), Toast.LENGTH_LONG).show();                             /**          * Call this function whenever you want to check user login          * This will redirect user to LoginActivity is he is not          * logged in          * */         session.checkLogin();                   // get user data from session         HashMap<String, String> user = session.getUserDetails();                   // name         String name = user.get(SessionManager.KEY_NAME);                   // email         String email = user.get(SessionManager.KEY_EMAIL);                   // displaying user data         lblName.setText(Html.fromHtml("Name: <b>" + name + "</b>"));         lblEmail.setText(Html.fromHtml("Email: <b>" + email + "</b>"));                             /**          * Logout button click event          * */         btnLogout.setOnClickListener(new View.OnClickListener() {                           @Override             public void onClick(View arg0) {                 // Clear the session data                 // This will clear all session data and                 // redirect user to LoginActivity                 session.logoutUser();             }         });     }           }

10. Open AndroidManifest.xml file, add the following code and run the project.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.androidhive.sessions"     android:versionCode="1"     android:versionName="1.0" >       <uses-sdk         android:minSdkVersion="8"         android:targetSdkVersion="15" />       <application         android:icon="@drawable/ic_launcher"         android:label="@string/app_name"         android:theme="@style/AppTheme" >         <activity             android:name=".MainActivity"             android:label="Dashboard Screen" >             <intent-filter>                 <action android:name="android.intent.action.MAIN" />                   <category android:name="android.intent.category.LAUNCHER" />             </intent-filter>         </activity>                   <!-- DashBoard / MainActivity -->         <activity             android:name=".LoginActivity"             android:label="User Login" >         </activity>     </application>   </manifest>

ABOUT THE AUTHOR

Ravi Tamada

Ravi is hardcore Android programmer and Android programming has been his passion since he compiled his first hello-world program. Solving real problems of Android developers through tutorials has always been interesting part for him.