Python+Tkinter+多线程的实例

Python是一种非常流行的编程语言，支持多种图形界面编程库，其中比较常用的是Tkinter。在Tkinter中，一般情况下GUI程序是单线程的，但可以利用多线程技术来实现一些特定功能的程序设计。本文将详细讲解如何使用Python+Tkinter+多线程编写程序，以实现更加高效的程序设计。

安装Python和Tkinter

在开始学习多线程编程之前， 需要安装Python和Tkinter。Python的下载地址是：https://www.python.org/downloads/，请选择最新版本下载。在Windows环境下，安装完成后，打开命令行窗口，使用pip安装Tkinter模块即可，命令如下：

pip install tkinter

在Linux环境下，使用以下命令安装Tkinter模块：

sudo apt-get install python-tk

多线程介绍

在这里简单介绍一下多线程。在Python中，多线程可以使用threading模块来实现。线程是操作系统能够进行运算调度的最小单位，它被包含在进程中，是比进程更小的能独立运行的基本单位。 通常的方法是定义一个函数来封装需要执行的操作，然后再创建一个线程并将该函数作为参数传递给该线程，等待该线程的执行结束。

案例1：多线程更新进度条

import threading
import tkinter as tk

class ProgressBarThread(threading.Thread):
    def __init__(self, progress_var, increment=1, sleep_time=0.1):
        threading.Thread.__init__(self)
        self.progress_var = progress_var
        self.increment = increment
        self.sleep_time = sleep_time

    def run(self):
        for i in range(101):
            self.progress_var.set(i)
            self.progress_var.update()
            if i == 100:
                self.progress_var.set(0)
                continue
            elif i < 70:
                self.sleep_time = 0.03
            elif i < 90:
                self.sleep_time = 0.05
            else:
                self.sleep_time = 0.1
            self.progress_var.increment(self.increment)
            time.sleep(self.sleep_time)

class Application(tk.Frame):
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.grid(sticky=tk.N+tk.S+tk.E+tk.W)

        self.progress_var = tk.DoubleVar()
        self.progress_var.set(0)
        self.progress = tk.ttk.Progressbar(self, orient="horizontal", mode="determinate", variable=self.progress_var)
        self.progress.grid(row=0, column=0, padx=5, pady=5, sticky=tk.N+tk.S+tk.E+tk.W)

        self.start_btn = tk.Button(self, text="Start", command=self.start_progress)
        self.start_btn.grid(row=1, column=0, padx=5, pady=5, sticky=tk.W)

        self.stop_btn = tk.Button(self, text="Stop", command=self.stop_progress)
        self.stop_btn.grid(row=1, column=0, padx=5, pady=5, sticky=tk.E)

        self.progress_thread = None

        self.progress_updated = False

    def start_progress(self):
        if self.progress_thread is not None and self.progress_thread.is_alive():
            return
        self.progress_thread = ProgressBarThread(self.progress_var, increment=1)
        self.progress_thread.start()

    def stop_progress(self):
        if self.progress_thread is None:
            return
        self.progress_var.set(0)
        self.progress_thread.join()
        self.progress_thread = None

if __name__ == '__main__':
    root = tk.Tk()
    app = Application(master=root)
    app.mainloop()

在这个案例中，我们将使用Tkinter的进度条控件来实现一个带有进度条的GUI程序。通过创建一个新的线程来不停的更新进度条，从而避免在主线程中执行这个任务，导致主界面卡顿。

案例2：多线程下载文件

import time
import threading
import tkinter as tk
from tkinter import messagebox
from tkinter.filedialog import askdirectory
import requests
import os

class DownloadThread(threading.Thread):
    def __init__(self, url, path):
        threading.Thread.__init__(self)
        self.url = url
        self.path = path
        self.download_flag = True

    def run(self):
        with requests.get(self.url, stream=True) as r:
            content_length = int(r.headers.get('Content-Length'))
            with open(self.path, 'wb') as f:
                for chunk in r.iter_content(chunk_size=1024):
                    if not self.download_flag:
                        return
                    if chunk:
                        f.write(chunk)
                        f.flush()

class DownloadApplication(tk.Frame):
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.grid(sticky=tk.N+tk.S+tk.E+tk.W)

        self.url_entry_label = tk.Label(self, text="URL:")
        self.url_entry_label.grid(row=0, column=0, padx=5, pady=5, sticky=tk.W)

        self.url_entry = tk.Entry(self)
        self.url_entry.grid(row=0, column=1, padx=5, pady=5, sticky=tk.W+tk.E)

        self.browse_button = tk.Button(self, text="Browse", command=self.select_download_path)
        self.browse_button.grid(row=1, column=0, padx=5, pady=5, sticky=tk.W)

        self.download_path_label = tk.Label(self, text="Download Path:")
        self.download_path_label.grid(row=1, column=1, padx=5, pady=5, sticky=tk.W)

        self.download_path_entry = tk.Entry(self)
        self.download_path_entry.grid(row=2, column=1, padx=5, pady=5, sticky=tk.W+tk.E)

        self.start_button = tk.Button(self, text="Start Download", command=self.start_download)
        self.start_button.grid(row=3, column=0, padx=5, pady=5, sticky=tk.W)

        self.stop_button = tk.Button(self, text="Stop Download", command=self.stop_download, state=tk.DISABLED)
        self.stop_button.grid(row=3, column=1, padx=5, pady=5, sticky=tk.E)

        self.download_thread = None

    def select_download_path(self):
        download_dir = askdirectory(title="Select Download Path")
        self.download_path_entry.delete(0, tk.END)
        self.download_path_entry.insert(tk.END, download_dir)

    def start_download(self):
        if not self.url_entry.get():
            messagebox.showinfo("Error", "Please input your url")
            return
        if not self.download_path_entry.get():
            messagebox.showinfo("Error", "Please select download path")
            return
        if self.download_thread is not None and self.download_thread.is_alive():
            messagebox.showinfo("Error", "Download task is already in progress")
            return
        url = self.url_entry.get()
        download_path = os.path.join(self.download_path_entry.get(), url.split("/")[-1])
        self.download_thread = DownloadThread(url, download_path)
        self.download_thread.start()
        self.start_button["state"] = tk.DISABLED
        self.stop_button["state"] = tk.NORMAL

    def stop_download(self):
        if self.download_thread is None:
            return
        self.download_thread.download_flag = False
        self.start_button["state"] = tk.NORMAL
        self.stop_button["state"] = tk.DISABLED

if __name__ == '__main__':
    root = tk.Tk()
    app = DownloadApplication(master=root)
    app.mainloop()

在这个案例中，我们将使用Tkinter创建一个GUI程序，可以输入URL，并且选择下载路径。同时在下载过程中，启动新的线程来执行下载操作，主线程负责更新进度条和响应“停止下载”操作。使用多线程可同时实现文件下载和下载进度的更新，而不会导致主界面卡顿。

以上两个案例给出的是Python+Tkinter+多线程实践的经典示例，想要掌握更多关于这方面的知识，需要对Python和Tkinter有更加深入全面的了解。