问题一：如何使用多线程？
问题内容：我们通过雅虎网站获取中国股市某支股票csv数据文件，现在要现在多只股票的csv数据，并将其转换为xml文件。
如何使用线程来提高下载并处理的效率？
解决方案：使用标准库threading.Thread 创建线程，在每个线程中下载并转换一支股票数据。
详细内容看代码：
import csv
from xml.etree.ElementTree import ElementTree,Element
import requests
from io import StringIO
from threading import Thread
def pretty(e,level=0):
if len(e) > 0:
e.text = '\n' + '\t' * (level + 1)
for child in e :
pretty(child,level + 1)
child.tail = child.tail[:-1]
e.tail = '\n' + '\t' * level
def download(url):
response = requests.get(url)
if response.ok:
return StringIO(response.text)
#download是一个IO操作，在发送请求之后，需要等待一段时间才会有结果
#在等待时间会让出CPU，当数据来的时候才会获得CPU的执行权
def csvToXml(scsv,fxml):
reader = csv.reader(scsv)
values = [row for row in reader]
headers = values[0]
headers = list(map(lambda h:h.replace(' ',''),headers))
#values = [value for value in values[1:] if value[0] >= '2017-01-01' ]
root = Element('Data')
for row in values[1:]:
if row[0] > '2017-01-01':
eRow = Element('Row')
root.append(eRow)
for tag,text in zip(headers,row):
e = Element(tag)
e.text = text
eRow.append(e)
pretty(root)
et = ElementTree(root)
et.write(fxml)
#使用线程进行下载转换
def handle(sid):
print('Download ... (%d)' % sid)
url = 'http://table.finance.yahoo.com/table.csv?s=%s.sz'
url %= str(sid).rjust(6, '0')
rf = download(url)
if rf is None: return
print('Convert to XML...(%d)' % sid)
fname = str(sid).rjust(6, '0') + '.xml'
with open(fname, 'wb') as wf:
csvToXml(rf, wf)
"""
通过线程对象开启线程
t = Thread(target=handle,args=(1,))
t.start()
"""
class MyThread(Thread):
def __init__(self,sid):
Thread.__init__(self)
self.sid = sid
def run(self):
handle(self.sid)
#同时创建十个线程
threads = []
for i in range(1,11):
t = MyThread(i)
threads.append(t)
t.start()
#主线程等待子线程退出之后退出
#t.join()
#等待所有子线程结束之后主线程再退出
for t in threads:
t.join()
print("main Thread")
# if __name__ == '__main__':
# # #下载单独的一只股票
# # url = 'http://table.finance.yahoo.com/table.csv?s=000001.sz'
# # rf = download(url)
# # if rf:
# # with open('000001.xml','wb') as wf:
# # csvToXml(rf,wf)
#
#
# #串行下载多只股票
# for sid in range(1,11):
# url ='http://table.finance.yahoo.com/table.csv?s=%s.sz'
# url %= str(sid).rjust(6,'0')
# rf = download(url)
# if rf is None: continue
#
# print('Convert to XML...(%d)' % sid)
# fname = str(sid).rjust(6,'0')+'.xml'
# with open(fname,'wb') as wf:
# csvToXml(rf,wf)
