如何将DJANGO轻量级化

看看这本书，应该有收获。

不用DJANGO-ADMIN STARTPROJECT XXX

一个文件，一样可以写出可以运行的原生DJANGO哟。

import hashlib
import sys
import os

from io import BytesIO
from PIL import Image, ImageDraw

from django.conf import settings

DEBUG= os.environ.get('DEBUG', 'on') == 'on'
SECRET_KEY = os.environ.get('SECRET_KEY', os.urandom(32))
BASE_DIR = os.path.dirname(__file__)
settings.configure(
    DEBUG=DEBUG,
    SECRET_KEY=SECRET_KEY,
    ROOT_URLCONF=__name__,
    MIDDLEWARE_CLASSES=(
        'django.middleware.common.CommonMiddleware',
        'django.middleware.csrf.CsrfViewMiddleware',
        'django.middleware.clickjacking.XFrameOptionsMiddleware',
        'django.middleware.cache.CacheMiddleware',

        ),
    INSTALLED_APPS=(
        'django.contrib.staticfiles',
        ),
    TEMPLATE_DIRS=(
        os.path.join(BASE_DIR, 'templates'),
        ),
    STATICFILES_DIRS=(
        os.path.join(BASE_DIR, 'static'),
        ),
    STATIC_URL='/static/',
    # STATIC_ROOT = os.path.join(BASE_DIR, 'static')
    )

from django import forms
from django.conf.urls import url
from django.core.cache import cache
from django.core.urlresolvers import reverse
from django.shortcuts import render
from django.http import HttpResponse, HttpResponseBadRequest
from django.views.decorators.http import etag
from django.core.wsgi import get_wsgi_application

class ImageForm(forms.Form):
    height = forms.IntegerField(min_value=1, max_value=2000)
    width = forms.IntegerField(min_value=1, max_value=2000)

    def generate(self, image_format='PNG'):
        height = self.cleaned_data['height']
        width = self.cleaned_data['width']
        key = '{}.{}.{}'.format(width, height, image_format)
        content = cache.get(key)
        if content is None:
            image = Image.new('RGB', (width, height))
            draw = ImageDraw.Draw(image)
            text = '{} X {}'.format(width, height)
            textwidth, textheight = draw.textsize(text)
            if textwidth < width and textheight < height:
                texttop = (height - textheight) // 2
                textleft = (width - textwidth) // 2
                draw.text((textleft, texttop), text, fill=(255,255,255))
            content = BytesIO()
            image.save(content, image_format)
            content.seek(0)
            cache.set(key, content, 60 * 60)
        return content

def generate_etag(request, width, height):
    content = 'Placeholder: {0} x {1}'.format(width, height)
    return hashlib.sha1(content.encode('utf-8')).hexdigest()

@etag(generate_etag)
def placeholder(request, width, height):
    form = ImageForm({'height': height, 'width': width})
    if form.is_valid():
        image = form.generate()
        return HttpResponse(image, content_type='image/png')
    else:
        return HttpResponseBadRequest('Invalid Image Request')

def index(request):
    example = reverse('placeholder', kwargs={'width': 50, 'height': 50})
    context = {
        'example': request.build_absolute_uri(example)
        }
    return render(request, 'home.html', context)

urlpatterns = (
    url(r'^$', index, name='home'),
    url(r'image/(?P<width>[0-9]+)x(?P<height>[0-9]+)/$',placeholder,
        name='placeholder'),
    )

application = get_wsgi_application()

if __name__ == '__main__':
    from django.core.management import execute_from_command_line

    execute_from_command_line(sys.argv)