text: # -*- coding: utf-8 -*- 
  """
  @author: xujingyi
  @date: 2017/8/28
  """
  # all the imports
  import os
  import sqlite3
  from flask import Flask, request, session, g, redirect, url_for, abort, \
      render_template, flash
  from flask import Flask
  
  app = Flask(__name__)
  app.config.from_object(__name__)  # load config from this file , flaskr.py
  
  # Load default config and override config from an environment variable
  app.config.update(dict(
      DATABASE=os.path.join(app.root_path, 'flaskr.db'),
      SECRET_KEY='development key',
      USERNAME='admin',
      PASSWORD='admin'
  ))
  
  app.config.from_envvar('FLASKR_SETTINGS', silent=True)
  
  
  def connect_db():
      """Connects to the specific database."""
      rv = sqlite3.connect(app.config['DATABASE'])
      rv.row_factory = sqlite3.Row
      return rv
  
  
  def get_db():
      """Opens a new database connection if there is none yet for the
      current application context.
      """
      if not hasattr(g, 'sqlite_db'):
          g.sqlite_db = connect_db()
      return g.sqlite_db
  
  
  @app.teardown_appcontext
  def close_db(error):
      """Closes the database again at the end of the request."""
      if hasattr(g, 'sqlite_db'):
          g.sqlite_db.close()
  
  
  def init_db():
      with app.app_context():
          db = get_db()
          with app.open_resource('schema.sql', mode='r') as f:
              db.cursor().executescript(f.read())
          db.commit()
  
  
  @app.route('/')
  def show_entries():
      g.sqlite_db = get_db()
      cur = g.sqlite_db.execute('SELECT title, text FROM entries ORDER BY id DESC')
      entries = [dict(title=row[0], text=row[1]) for row in cur.fetchall()]
      return render_template('show_entries.html', entries=entries)
  
  
  @app.route('/add', methods=['POST'])
  def add_entry():
      if not session.get('logged_in'):
          abort(401)
      g.db.execute('INSERT INTO entries (title, text) VALUES (?, ?)',
                   [request.form['title'], request.form['text']])
      g.db.commit()
      flash('New entry was successfully posted')
      return redirect(url_for('show_entries'))
  
  
  @app.route('/login', methods=['GET', 'POST'])
  def login():
      error = None
      if request.method == 'POST':
          if request.form['username'] != app.config['USERNAME']:
              error = 'Invalid username'
          elif request.form['password'] != app.config['PASSWORD']:
              error = 'Invalid password'
          else:
              session['logged_in'] = True
              flash('You were logged in')
              return redirect(url_for('show_entries'))
      return render_template('login.html', error=error)
  
  
  @app.route('/logout')
  def logout():
      session.pop('logged_in', None)
      flash('You were logged out')
      return redirect(url_for('show_entries'))
  
  
  if __name__ == '__main__':
      app.run()
  