前言

上週電腦重灌，換了ubuntu 16.04，想起來之前上課老師也是ubuntu而且他還提到他桌面是他自己寫的個小指令碼實現的自動更換桌面桌布的，昨天晚上心血來潮自己網上搜了點資料實現了一下 = =

功能

功能的話，是從必應桌布爬取最新的那張桌布，然後本來因為我怕電腦又放了太多東西，就設定了個圖片最大的數目，到達這個閾值就刪除所有的圖片= =|| 通過python的os模組，設定桌布，這裡可以參考：how-to-change-desktop-background-from-command-line-in-unity , 還有就是考慮到剛開機時我不一定連得上網（辛酸 T_T)，所以設定了一個爬取的間隔

程式碼

# -*- coding: utf-8 -*-
#!/usr/bin/python
#!/bin/bash


# ---------------------------------------------------------- #
# This is a script which can change background automatically #
# every time the system starts.                               #
# author: Huang Zhenyang                                     #
 

# email: [email protected]                                    #
# ---------------------------------------------------------- #

# ----- Import ----- #
import os
import re
import urllib
import time
import socket
# --- End Import --- #


class Spider(object):
    """
    This is the spider to get the img from being
    """
 


    def __init__( self, img_matched_pattern_para, url_para, file_name_para ):
        """
        init function
        :param img_matched_pattern_para: the pattern to match a img
        :param url_para: url to crawler
        :param file_name_para: file name
        """
        self.img_matched_pattern = img_matched_pattern_para
        self.url = url_para
        self.file_name = file_name_para

    def get_img(self):
        """
        download the image
        :return:
        """
        html = self.get_html()
        img_pos = re.search(self.img_matched_pattern, html)
        img_page_href = self.url + img_pos.group()[6:-7] + "download"
        urllib.urlretrieve(img_page_href, self.file_name)


    def get_html(self):
        """
        return the html
        :return: page's html <type 'str'>
        """
        page = urllib.urlopen(self.url)
        html = page.read()
        return html


class Controller(object):
    """
    This is the controller to control the spider's parameters.
    """

    def __init__(self, pattern_href_para, path_para, url_para, img_max_num_para):
        """
        :param pattern_href_para: href's match pattern
        :param path_para: path to save images
        :param url_para: url
        :param img_max_num_para: max number that the
        """
        self.pattern_href = pattern_href_para
        self.path = path_para
        self.url = url_para
        self.img_max_num = img_max_num_para
        self.file_name = ""
        self.init_file_name = "0.jpg"
        self.file_extension_name = ".jpg"

    def judge(self):
        """
        judge if the number of images is grater than img_max_num.
        if true, delete all of them and then run spider, else directly run spider.
        Also, we should set the file name.
        :return:
        """
        root = None
        _dirs = None
        files = None
        for root, _dirs, files in os.walk(self.path, True):
            pass

        files_len = len(files)

        if files_len == 10:
            for i in range(0, 10):
                os.remove(root + files[i])
            self.file_name = self.path + self.init_file_name
        else:
            self.file_name = self.path + str(files_len) + self.file_extension_name

    def run_spider(self):
        """
        run spider.
        TODO: This function needs to be modified in the future which makes these two class coupling too much.
        :return:
        """
        # In case user's computer hasn't connect the internet.
        for i in range(0, 60):
            try:
                spider = Spider(self.pattern_href, self.url, self.file_name)
                spider.get_img()

                break

            except IOError as e:
                print "Connection error: %s" % e
                time.sleep(60)
                continue

            except Exception as e:
                print "Connection error: %s" % e
                time.sleep(60)
                continue

        c_path = '"file://' + self.file_name + '"'  # absolute path
        # call system command to change the gnome background
        os.system('gsettings set org.gnome.desktop.background picture-uri ' + c_path)
        print "gsettings set org.gnome.desktop.background picture-uri " + c_path


if __name__ == '__main__':
    pattern_href = r'href="/photo/.*?"'
    path = '/home/hzy/圖片/backgrounds/'
    url = 'https://bing.ioliu.cn/'
    img_max_num = 10

    controller = Controller(pattern_href, path, url, img_max_num)
    controller.judge()
    controller.run_spider()

開機自啟動

在/home/hzy/.config/autostart中，新建一個xxx.desktop的檔案，內容如下：

[Desktop Entry]
Name=autoChangeBackgroundImg
Comment=Python Program
Exec=python /home/hzy/Script/autoChangeBackgroundImg/autoChangeBackgroundImg.py
Icon=/home/hzy/Script/autoChangeBackgroundImg/autoChangeBackgroundImg.png
Terminal=false
MultipleArgs=false
Type=Application
Categories=Application;Development;
StartupNotify=true

說明：
1. Exec 後面的路徑就是該指令碼的路徑
2. Icon的話可以自己隨便找個圖片，設定成該路徑即可