python下的開發框架挺多，Django,Tornado,Flask…,我們選用了Django來做演示是因為Django的restful框架-djangorestframework開發RestfulAPI足夠簡單成熟。目前Django的最新版本為1.9，而Django從1.7開始已經對Python的最低版本要求到2.7以上了，雖然官方推薦使用Python3，但筆者還是建議使用2.7，因為很多python下的輪子都不是很支援Python3，例如Twisted(Python的網路開發框架)也是最近才開始支援Python3。

我們先搭建基礎環境

我們建立一個Centos6.6的虛擬機器，這裡做一個小筆記，關於VisualBox如何快速克隆Centos虛擬機器：
1.複製虛擬電腦彈出框，勾選重新初始化所有網絡卡的MAC地址

2.將/etc/udev/rules.d/70-persistent-net.rules中的eth1 MAC地址覆蓋到/etc/sysconfig/network-scripts/ifcfg-eth0中的HWADDR,修改DEVICE=eth1
3.重啟網路 /etc/init.d/network restart

centos預設的python是2.6的，我們需要下載2.7原始碼覆蓋安裝

> yum install -y wget gcc sqlite-devel openssl-devel zlib-devel
> cd /tmp/
> wget https://www.python.org/ftp/python/2.7.10/Python-2.7.10.tgz
 

> tar -xf Python-2.7.10.tgz 
> cd Python-2.7.10
> ./configure
> make
> make install
> wget https://bootstrap.pypa.io/ez_setup.py -O - | sudo /usr/local/bin/python
> easy_install django
> easy_install djangorestframework
> easy_install django-cors-headers

建立專案

> django-admin startproject RestfulProject
 

> cd RestfulProject
> python manage.py startapp database

將database加入到INSTALLED_APPS

# RestfulProject/settings.py
INSTALLED_APPS = (
    ...
    "database",
    ...
)

資料庫建模

# database/models.py
from django.db import models
from django.utils import timezone

class News(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField(blank=True)
    create_time = models.DateTimeField(default=timezone.now)

將News加入到django的後臺自動化管理django-admin中

# database/admin.py
from django.contrib import admin
from .models import *
admin.site.register(News)

資料庫初始化

> python manage.py makemigrations database
> python manage.py migrate
> python manage.py createsuperuser

一個Django的基礎專案即完成，我們跑起來，看看

> python manage.py runserver 0.0.0.0:8000

我們用djangorestframework來構建最簡單的CRUD

# RestfulProject/settings.py
INSTALLED_APPS = (
    ...
    'rest_framework',
)

# RestfulProject/views.py
from rest_framework import serializers,viewsets
from database.models import News

class NewsSerializer(serializers.ModelSerializer):
    class Meta:
        model = News
class NewsViewSet(viewsets.ModelViewSet):
    serializer_class = NewsSerializer
    queryset = News.objects.all()

# RestfulProject/urls.py
...
from django.conf.urls import include
from rest_framework import routers
from RestfulProject.views import NewsViewSet

router = routers.DefaultRouter()
router.register(r'news', NewsViewSet,base_name='news')

urlpatterns = [
    url(r'^', include(router.urls)),
    ...
]

我們可以使用postman來測試我們寫好的介面，但是djangorestframework本身集成了webapi的線上瀏覽功能，可以更方便的測試

我們來整合BasicAuth驗證功能，djangorestframework的預設驗證是使用django自帶的session驗證，我們首先來看看預設的驗證是怎樣的

# RestfulProject/views.py
from rest_framework.permissions import IsAuthenticated
class NewsViewSet(viewsets.ModelViewSet):
    ...
    permission_classes = (IsAuthenticated,)

我們再訪問這個介面將返回403錯誤

我們來將預設認證換成BasicAuth

# RestfulProject/settings.py
REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': [
        'rest_framework.authentication.BasicAuthentication',
    ],
}

再訪問這個介面將返回401錯誤，瀏覽器根據該錯誤將彈出認證介面

按照制定的介面文件，我們再補全一個認證介面給客戶端登入使用

# RestfulProject/views.py
from rest_framework.views import APIView
from rest_framework.response import Response

class UserViewSet(APIView):
    permission_classes = (IsAuthenticated,)
    def get(self, request):
        content = {
            'userid':request.user.id,
            'username':request.user.username,
        }
        return Response(content)

# RestfulProject/urls.py
from RestfulProject.views import UserViewSet

urlpatterns = [
    ...
    url(r'^auth/info/$', UserViewSet.as_view()),
]

書寫擴充套件的協議-批量刪除
編輯RestfulProject/views.py

# RestfulProject/views.py
from rest_framework.decorators import list_route
from rest_framework import status

class NewsViewSet(viewsets.ModelViewSet):
    ...
    @list_route(methods=['delete',])
    def deletes(self, request, **kwargs):
        ids = request.GET['ids'].split(',')
        News.objects.filter(id__in=ids).delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

書寫擴充套件協議-搜尋

# RestfulProject/views.py
class NewsViewSet(viewsets.ModelViewSet):
    serializer_class = NewsSerializer
    permission_classes = (IsAuthenticated,)
    #queryset = News.objects.all()
    def get_queryset(self):
        if not 'search' in self.request.GET:
            ft = News.objects.all()
        else:
            ft = News.objects.filter(title__contains=self.request.GET['search'])
        return ft.order_by('-create_time')

書寫擴充套件協議-分頁

# RestfulProject/pagination.py
from rest_framework.pagination import PageNumberPagination
from rest_framework.response import Response
from collections import OrderedDict

class StandardResultsSetPagination(PageNumberPagination):
    page_size = 50
    page_size_query_param = 'page_size'
    max_page_size = 1000
    def get_paginated_response(self, data):
        return Response(OrderedDict([
            ('total_count', self.page.paginator.count),
            ('page_count',self.page.paginator.num_pages),
            ('next', self.get_next_link()),
            ('previous', self.get_previous_link()),
            ('results', data)
        ]))

# RestfulProject/settings.py
REST_FRAMEWORK = {
    ...
    'DEFAULT_PAGINATION_CLASS': 'RestfulProject.pagination.StandardResultsSetPagination',
}

後端基本完成了，還剩下最後一個問題CORS，我們在本地寫一個簡單的jquery

<script src="http://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script>
<script>
$.get("http://172.17.9.177:8000/news/");
</script>

在chrome裡面除錯一下會出現如下錯誤

XMLHttpRequest cannot load http://172.17.9.177:8000/news/. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 401.

我們用django-cors-headers來解決這個問題：

# RestfulProject/settings.py
INSTALLED_APPS = (
    ...
    'corsheaders',
    ...
)

將cors中介軟體放置在django.middleware.common.CommonMiddleware之前

# RestfulProject/settings.py
MIDDLEWARE_CLASSES = (
    ...
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
    ...
)

設定任意網址的跨域請求都被伺服器接受

# RestfulProject/settings.py
CORS_ORIGIN_ALLOW_ALL = True

再次用jquery測試，之前那個錯誤將不再出現。