python多线程返回值的实现与处理

题目：

# 编写一个python程序，创建两个子线程，分别到下面的网址获取文本内容
# http://mirrors.163.com/centos/6/isos/x86_64/README.txt
# http://mirrors.163.com/centos/7/isos/x86_64/0_README.txt
# 主线程等待这个两个子线程获取到信息后，将其内容依次合并后存入名为 readme89.TXT 的文件中

答案1：通过返回值实现

1、创建线程类，重构线程基类初始化函数

from threading import Thread

# 创建一个线程类
class MyThread(Thread):
    # 重定义初始化
def __init__(self,func,args=()):
        super(MyThread, self).__init__()
        self.func = func
        self.args = args

    # 运行函数（线程）
def run(self):
        self.rusult = self.func(*self.args) 

    # 获得返回值
def get_result(self):
        Thread.join(self) # 等待线程执行完毕
try:
            return self.rusult
        except Exception:
            return None

2、创建子线程实现调用返回值的操作

import requests,traceback
from pythondevelop.case_1109ReturnValue import MyThread

# 创建两个子线程用于获取网页内容
def thread1():
    r = requests.get('http://mirrors.163.com/centos/6/isos/x86_64/README.txt')

    return r  

def thread2():
    r = requests.get('http://mirrors.163.com/centos/6/isos/x86_64/0_README.txt')

    return r

# 主程序等待子线程获取后合并内容到readme89.TXT
try:
    th1= MyThread(thread1)
    th2= MyThread(thread2)
    th1.start()
    th2.start()
    th1result = th1.get_result()
    th2result = th2.get_result()
    if th1result != None and th2result != None and th1result.status_code == 200 and th2result.status_code == 200:
        with open('readme89.txt','w+') as f:
            f.write(th1result.text)
            f.write('---------------------------------------this is line!!-------------------------------------')
            f.write(th2result.text)
            f.close()
except:
    print(traceback.format_exc())

答案2：通过将返回值放在预先定义的列表中，及对线程锁的应用

# coding=utf8
import requests,threading

urls = [
'http://mirrors.163.com/centos/6/isos/x86_64/README.txt',
'http://mirrors.163.com/centos/6/isos/x86_64/0_README.txt']

# 对应urls 依次存储网页文件内容, 先创建同样个数的元素占位
fileContentList = [None for one in urls]

# 锁对象，用来控制访问 fileContentList
lock = threading.Lock()

def thread_entry(idx,url):
    print('thread #%s start' % idx)
    r = requests.get(url)

    # 注意上面的代码不应该放在获取锁的代码中
    lock.acquire()
    # 注意 r.text的类型是unicode，可以在文档中查到
    fileContentList[idx] = r.text
    lock.release()

    print('thread #%s end' % idx)

if __name__ == '__main__':
    print('main thread start.')

    threadpool = []

    for idx,url in enumerate(urls): # enumerate()用于遍历数据对象(如列表)组合为一个索引序列，同时列出下标和数据
        t = threading.Thread(target=thread_entry,args=(idx,url))
        t.start()

        threadpool.append(t)

    # 等所有 线程结束
    for t in threadpool:
        t.join()

    # 所有线程结束后，所有内容都获取到了，合并内容

    mergeTxt = '\n\n----------------------\n\n'.join(fileContentList)
    print(mergeTxt)

    with open('readme89.txt','w',encoding='utf8') as f:
        f.write(mergeTxt)

    print('main thread end.')