（url）（进程的两种创建方式）（进程池）

#***************************************************************************
# python的通信模块：1，urllib  2，requests
# url 统一资源定位器，也就是文件的路径，网址，是一个字符串
# response = request.urlopen(url)发起请求并得到响应
import urllib
from urllib import request
url='https://img.zcool.cn/community/01b82f5bac3a7aa801213deadb1922.jpg@1280w_1l_2o_100sh.jpg'
def downloader(url):
    response = request.urlopen(url)
    # print(response,type(response))
    content = response.read()
    # print(content,type(content))  # <class 'bytes'>
    file_name = url.split('/')[-1]
    with open(file_name,'wb') as f:
        f.write(content)
downloader(url)
#************下面一个，展示进程的效果****************************************

from multiprocessing import Process
import time
def dance():
    for i in range(3):
        print('跳第%d段舞'%i)
        time.sleep(0.5)
def sing():
    for i in range(4):
        print('唱第%d首歌'%i)
        time.sleep(0.5)
if __name__ == '__main__':
    p1 = Process(target=dance)
    p2 = Process(target=sing)
    p1.start()
    p2.start()
#***********用进程实现下载器*****************************************

from multiprocessing import Process
from urllib import request
import os

def downloader(url,**priority):
    print(priority['pri'],'进程ID:',os.getpid(),'父进程ID',os.getppid())

    file_name = url.split('/')[-1]
    response = request.urlopen(url)
    content = response.read()
    with open(file_name,'wb') as fp:
        fp.write(content)

url_list = ['https://img.zcool.cn/community/01b82f5bac3a7aa801213deadb1922.jpg@1280w_1l_2o_100sh.jpg',
               'https://img.zcool.cn/community/01f1d05bac3a7ba801213dea985ecb.jpg@1280w_1l_2o_100sh.jpg',
               'https://img.zcool.cn/community/01ccf65bac3a7ea8012099c8d65a89.jpg@1280w_1l_2o_100sh.jpg',
               'https://img.zcool.cn/community/01e6435bac3a81a8012099c8ed4c5c.jpg@1280w_1l_2o_100sh.jpg',
               'https://img.zcool.cn/community/010f465bac3a8ba801213dea44adaf.jpg@1280w_1l_2o_100sh.jpg',

               ]
p_list = []
name_list = ['进程一：张三','进程二：李四','进程三：王五','进程四：赵六','进程五：刘七']
pri_dit = [{'pri':'1'},{'pri':'0.9'},{'pri':'0.5'},{'pri':'0.1'},{'pri':'0'}]
if __name__ == '__main__':
    i = 0
    for url in url_list:
        p = Process(target=downloader,name=name_list[i],args=(url_list[i],),kwargs=pri_dit[i])
        i+=1
        p_list.append(p)
    for p in p_list:
        p.start()
        print(p.name,'starts to work')
    for p in p_list:
        p.join()
    print('主进程id',os.getpid())
#***********创建进程的第二种方式，继承Process类*****************************************

from multiprocessing import Process
import os
from urllib import request

#步骤1：继承Process类
class Process_Class(Process):

    # 因为Process类本身也有__init___方法，这个子类相当于重写了这个方法。
    # 但这样会带来一个问题，我们并没有完成的初始化一个进程类，所以就不能使用这个类继承的一些方法和属性。
    #步骤2：使用父类初始化方法初始子类
    def __init__(self,url):
        Process.__init__(self)
        self.url = url

    #步骤3：重写Process类中的run方法
    def run(self):
        print('当前进程id:', os.getpid(), os.getppid())

        # 文件名
        file_name = self.url.split('/')[-1]

        # 网络请求
        response = request.urlopen(self.url)  # 一个响应对象

        # 获取响应的内容
        content = response.read()

        # 保存
        with open(file_name, 'wb') as fp:
            fp.write(content)

if __name__ == '__main__':
    url_list = [
        'https://www.baidu.com/img/baidu_jgylogo3.gif',
        'http://www.offcn.com/statics/images/zgimg/index2019.png'
    ]
    for url in url_list:
        p = Process_Class(url)
        p.start()


#***********进程池*****************************************

        from multiprocessing import Pool
        import time, random


        def worker(msg):
            t_start = time.time()

            print('%s--开始执行' % (msg))
            time.sleep(random.random())  # 模拟工作所消耗的时间

            t_end = time.time()
            print('%s--执行完毕,消耗时间为：%0.2f' % (msg, t_end - t_start))


        if __name__ == '__main__':
            p = Pool(3)  # 创建一个容量是3的进程池
            for i in range(10):
                # 将进程添加到进程池，
                # 格式：进程池.apply_async(func=单个进程要调用的目标，args=(参数1，参数2....))
                # 每次循环将会用空闲的子进程去调用目标
                p.apply_async(func=worker, args=(i,))  # 异步操作
                # p.apply(func=worker,args=(i,))#串行操作

            print('-----------start----------')
            # 关闭进程池，关闭后进程池将不再接收新的任务
            p.close()
            # 等待进程池中的所有子进程都结束后，注意：join一定要放在close后面。
            p.join()
            print('------------end----------')
#****************************************************