python-初识多任务线程

1.多任务基本介绍

有很多的场景中的事情是同时进行的，比如开车的时候手和脚共同来驾驶汽车，再比如唱歌跳舞也是同时进行的

1.1 程序中模拟多任务

1 import time
2 3
def sing():
4 for i in range(3):
5 print("正在唱歌...%d"%i)
6 time.sleep(1)
7 8
def dance():
9 for i in range(3):
10 print("正在跳舞...%d"%i)
11 time.sleep(1)
12
13 if __name__ == '__main__':
14 sing()
15 dance()

2. 主线程和子线程的执行关系

主线程会等待子线程结束之后在结束

import threading
import time

def demo():
    for i in range(5):
        print('hello world')
        time.sleep(1)


if __name__ == '__main__':

    t = threading.Thread(target=demo)
    t.start() # 启动线程 主线程会等待子线程结束之后 主线程在结束
    print(1)
# 输出
hello world
1
hello world
hello world
hello world
hello world

join() 等待子线程结束之后，主线程继续执行

import threading
import time

def demo():
    for i in range(5):
        print('hello world')
        time.sleep(1)

if __name__ == '__main__':

    t = threading.Thread(target=demo)
    t.start() # 启动线程 主线程会等待子线程结束之后 主线程在结束
    t.join() # 等待子线程结束之后，主线程继续执行
    print(1)
# 输出
hello world
hello world
hello world
hello world
hello world
1

setDaemon() 守护线程，不会等待子线程结束

import threading
import time

def demo():
    for i in range(5):
        print('hello world')
        time.sleep(1)

if __name__ == '__main__':

    t = threading.Thread(target=demo)
    t.setDaemon(True) # 守护线程 不会等待子线程结束
    t.start() 
    print(1)
# 输出
hello world
1

实例1

import threading
import time
def singe():

    for i in range(3):

        print('正在唱歌....')
        time.sleep(1)


def dance():
    for i in range(3):
        print('正在跳舞....')
        time.sleep(1)

def main():

    t1 = threading.Thread(target=singe)
    t2 = threading.Thread(target=dance)

    t1.start()
    t2.start()
if __name__ == '__main__':
    main() 
# 输出
正在唱歌....
正在跳舞....
正在唱歌....
正在跳舞....
正在唱歌....
正在跳舞....

实例2

1 import threading
2 import time
3 
4 def demo():
5 # 子线程
6 print("hello girls")
7 time.sleep(1)
8
9 if __name__ == "__main__":
10 for i in range(5):
11 t = threading.Thread(target=demo)
12 t.start()

3. 查看线程数量

1 threading.enumerate() 查看当前线程的数量

import threading

import time
def demo1():

    for i in range(5):

        print('demo1--%d'%i)
        time.sleep(1)


def demo2():

    for i in range(10):
        print('demo2--%d' % i)
        time.sleep(1)


def main():

    t1 = threading.Thread(target=demo1,name = 'demo1')
    t2 = threading.Thread(target=demo2,name = 'demo2')

    t1.start()
    t2.start()

    while True:


        print(threading.enumerate())

        if len(threading.enumerate()) <= 1:
            break

        time.sleep(1)

if __name__ == '__main__':

    main()

4. 验证子线程的执行与创建

当调用Thread的时候，不会创建线程。当调用Thread创建出来的实例对象的start方法的时候，才会创建线程以及开始运行这个线程。

继承Thread类创建线程

import threading

import time

class Main(threading.Thread):

    def run(self):

        for i in range(5):

            print(i)


if __name__ == '__main__':

    m = Main()
    m.start()

1 import threading
2 import time
3 
4 class A(threading.Thread):
5 
6 	def __init__(self,name):
7 		super().__init__(name=name)
8 
9 	def run(self):
10 		for i in range(5):
11 			print(i)
12
13 if __name__ == "__main__":
14 t = A('test_name')
15 t.start()

5. 线程间的通信(多线程共享全局变量)

在一个函数中，对全局变量进行修改的时候，是否要加global要看是否对全局变量的指向进行了修改，如果修改了指向，那么必须使用global，仅仅是修改了指向的空间中的数据，此时不用必须使用global线程是共享全局变量

import threading
import time

# 线程间是共享的全局变量
num = 100
def demo1():
    global num
    num += 1
    print('demo1--%d'% num)

def demo2():
    print('demo2--%d' % num)

def main():

    t1 = threading.Thread(target = demo1)
    t2 = threading.Thread(target = demo2)

    t1.start()
    time.sleep(1) # 保证demo1先执行
    t2.start()

    print('main-num=%s'% str(num))

if __name__ == '__main__':

    main()

5.1 多线程参数-args

1 threading.Thread(target=test, args=(num,))

import threading
import time

num = [11,22]

def demo1(nums):

    num.append(nums)
    print('demo1--%s'% str(num))

def demo2():

    print('demo2--%s' % str(num))


def main():

    t1 = threading.Thread(target = demo1,args=(33,))
    t2 = threading.Thread(target = demo2)

    t1.start()
    time.sleep(1) # 保证demo1先执行
    t2.start()
    print('main-num=%s'% str(num))

if __name__ == '__main__':

    main()

6. 制作一个摸奖转盘

# 1.有12个备选选项和2个功能按钮 确定备选选项和功能按钮的位置

# 2.点击开始会不断旋转。选中的时候背景颜色为红色，点击停止结束

import threading

import tkinter

import time

# 1.实现窗口

root = tkinter.Tk()

root.title('抽奖，试试手气')

root.minsize(300,300)

# 2 摆放按钮
btn1 = tkinter.Button(root, text='1元', bg='red')
btn1.place(x=20, y=20, width=50, height=50)

btn2 = tkinter.Button(root, text='50元', bg='white')
btn2.place(x=90, y=20, width=50, height=50)

btn3 = tkinter.Button(root, text='100元', bg='white')
btn3.place(x=160, y=20, width=50, height=50)

btn4 = tkinter.Button(root, text='1万', bg='white')
btn4.place(x=230, y=20, width=50, height=50)

btn5 = tkinter.Button(root, text='单车', bg='white')
btn5.place(x=230, y=90, width=50, height=50)

btn6 = tkinter.Button(root, text='摩托', bg='white')
btn6.place(x=230, y=160, width=50, height=50)

btn7 = tkinter.Button(root, text='汽车', bg='white')
btn7.place(x=230, y=230, width=50, height=50)

btn8 = tkinter.Button(root, text='法拉利', bg='white')
btn8.place(x=160, y=230, width=50, height=50)

btn9 = tkinter.Button(root, text='宾利', bg='white')
btn9.place(x=90, y=230, width=50, height=50)

btn10 = tkinter.Button(root, text='直升机', bg='white')
btn10.place(x=20, y=230, width=50, height=50)

btn11 = tkinter.Button(root, text='别墅', bg='white')
btn11.place(x=20, y=160, width=50, height=50)

btn12 = tkinter.Button(root, text='航母', bg='white')
btn12.place(x=20, y=90, width=50, height=50)

#2.1将所有的选项放到列表中 目的：为了操作这些选项
hero_list = [btn1,btn2,btn3,btn4,btn5,btn6,btn7,btn8,btn9,btn10,btn11,btn12]


# 定义一个标记
stop_sign = False # 默认是停止

stop_id = None

# 3 定义一个函数 1.循环备选选项 2.设置选项颜色
def round():

    global stop_id

    i = 1

    if isinstance(stop_id,int):

        i = stop_id

    while True:

        time.sleep(0.3)


        for x in hero_list:

            x['bg'] = 'white'


        hero_list[i]['bg'] = 'red'


        i += 1

        print('当前的i为:',i)

        if i >= len(hero_list):

            i = 0

        if stop_sign == True:

            stop_id = i

            break

# 4 定义停止的方法
def stop():

    global stop_sign

    if stop_sign == True:

        return

    stop_sign = True




# 5 定义开始的方法

def newtask():

    global stop_sign

    stop_sign = False


    t = threading.Thread(target=round)


    t.start()

# 6.设置按钮
btn_start = tkinter.Button(root,text='开始',command=newtask)

btn_start.place(x=90,y=125,width=50,height=50)


btn_stop = tkinter.Button(root,text='停止',command=stop)

btn_stop.place(x=160,y=125,width=50,height=50)


# 显示窗口
root.mainloop()

运行后效果