There are two ways to save data globally:
1. Save data in global variables:If we are storing data in global variable , data will be lost once user closes the application.
2. Save the data in shared preferences:
If we are Storing data in shared preferences will be persistent to all application even after user closes the application. You can save key, value pair data in Shared preferences.
FILE : UserSessionManager.java
This class contain all user session related functions.
In this class file creating SharedPreferences and inserting / updating / deleting user session data from SharedPreferences.
further explanation given as comment in class code.
package com.androidexample.usersessions;
import java.util.HashMap;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
public class UserSessionManager {
// Shared Preferences reference
SharedPreferences pref;
// Editor reference for Shared preferences
Editor editor;
// Context
Context _context;
// Shared pref mode
int PRIVATE_MODE = 0;
// Sharedpref file name
private static final String PREFER_NAME = "AndroidExamplePref";
// All Shared Preferences Keys
private static final String IS_USER_LOGIN = "IsUserLoggedIn";
// 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 UserSessionManager(Context context){
this._context = context;
pref = _context.getSharedPreferences(PREFER_NAME, PRIVATE_MODE);
editor = pref.edit();
}
//Create login session
public void createUserLoginSession(String name, String email){
// Storing login value as TRUE
editor.putBoolean(IS_USER_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 will check user login status
* If false it will redirect user to login page
* Else do anything
* */
public boolean checkLogin(){
// Check login status
if(!this.isUserLoggedIn()){
// user is not logged in redirect him to Login Activity
Intent i = new Intent(_context, LoginActivity.class);
// Closing all the Activities from stack
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);
return true;
}
return false;
}
/**
* Get stored session data
* */
public HashMap getUserDetails(){
//Use hashmap to store user credentials
HashMap user = new HashMap();
// 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 user data from Shared Preferences
editor.clear();
editor.commit();
// After logout redirect user 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);
}
// Check for login
public boolean isUserLoggedIn(){
return pref.getBoolean(IS_USER_LOGIN, false);
}
}
FILE : LoginActivity.java
This is the first screen( Login screen ).
For Login using Username: admin and Password: admin
Using createUserLoginSession() to save user data in SharedPreferences for further use.
package com.androidexample.usersessions;
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 {
Button btnLogin;
EditText txtUsername, txtPassword;
// User Session Manager Class
UserSessionManager session;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// User Session Manager
session = new UserSessionManager(getApplicationContext());
// get Email, Password input text
txtUsername = (EditText) findViewById(R.id.txtUsername);
txtPassword = (EditText) findViewById(R.id.txtPassword);
Toast.makeText(getApplicationContext(),
"User Login Status: " + session.isUserLoggedIn(),
Toast.LENGTH_LONG).show();
// User 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();
// Validate if username, password is filled
if(username.trim().length() > 0 && password.trim().length() > 0){
// For testing puspose username, password is checked with static data
// username = admin
// password = admin
if(username.equals("admin") && password.equals("admin")){
// Creating user login session
// Statically storing name="Android Example"
// and email="androidexample84@gmail.com"
session.createUserLoginSession("Android Example",
"androidexample84@gmail.com");
// Starting MainActivity
Intent i = new Intent(getApplicationContext(), MainActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
// Add new Flag to start new Activity
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(i);
finish();
}else{
// username / password doesn't match&
Toast.makeText(getApplicationContext(),
"Username/Password is incorrect",
Toast.LENGTH_LONG).show();
}
}else{
// user didn't entered username or password
Toast.makeText(getApplicationContext(),
"Please enter username and password",
Toast.LENGTH_LONG).show();
}
}
});
}
}
FILE : activity_login.xml
This file is used as layout file in LoginActivity.java.
It will create login screen design.
android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:padding="10dip"> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Username (Enter 'admin')" android:singleLine="true" android:layout_marginBottom="5dip"/> <EditText android:id="@+id/txtUsername" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginBottom="10dip"/> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Password (Enter 'admin')" android:layout_marginBottom="5dip"/> <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"/> <Button android:id="@+id/btnLogin" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Login"/></LinearLayout>FILE : MainActivity.java
This is the welcome screen after user login.
Get user data from SharedPreferences and show on activity.
package com.androidexample.usersessions;
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 {
// User Session Manager Class
UserSessionManager session;
// Button Logout
Button btnLogout;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Session class instance
session = new UserSessionManager(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.isUserLoggedIn(),
Toast.LENGTH_LONG).show();
// Check user login (this is the important point)
// If User is not logged in , This will redirect user to LoginActivity
// and finish current activity from activity stack.
if(session.checkLogin())
finish();
// get user data from session
HashMap user = session.getUserDetails();
// get name
String name = user.get(UserSessionManager.KEY_NAME);
// get email
String email = user.get(UserSessionManager.KEY_EMAIL);
// Show user data on activity
lblName.setText(Html.fromHtml("Name: " + name + ""));
lblEmail.setText(Html.fromHtml("Email: " + email + ""));
btnLogout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Clear the User session data
// and redirect user to LoginActivity
session.logoutUser();
}
});
}
}
FILE : activity_login.xml
This file is used as layout file in MainActivity.java.
It will create Welcome screen (after login) design.
android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:padding="10dip"> <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"/> <TextView android:id="@+id/lblEmail" android:layout_width="fill_parent" android:layout_height="wrap_content" android:singleLine="true" android:layout_marginBottom="40dip"/> <Button android:id="@+id/btnLogout" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="Logout"/> </LinearLayout>
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