使用彩色字符在命令行输出，可以极大提高程序输出的可读性。本文将介绍如何使用 Python 在命令行进行彩色字符输出。
1. 原理解析 - ANSI 转义序列
在命令行输出彩色信息，并不是编程语言的特有特性，而是利用了 ANSI 转义序列。无论使用何种编程语言，只要正确使用 ANSI 转义序列，便可以打印出彩色的命令行字符。
值得注意的是，不同系统对于 ANSI 转义序列支持不尽相同。
详细可见：
2. 使用 Python 输出彩色字符
2.1 ANSI 转义序列的系统支持
类 Unix 系统对于 ANSI 转义序列支持十分完善，如：Linux、MacOS
而 Windows 系统直到 Window 10 Th2 版本才开始原生支持部分的 ANSI 转义序列（为了支持 Subsystem Linux）。所以只有 Th2 之后版本的 Window 10，自带的 cmd、powershell 才开始支持 ANSI 转义序列。
在 Windows 上可以使用第三方的终端模拟软件来支持转义序列，也可以安装基于 .Net Core 的 Powershell 6（简称 pwsh，支持 side by side 安装，支持 ANSI 转义序列）。
一个值得关注的点是，一般的 IDE 内置的执行命令行均与系统默认 cmd、powershell 有区别，它们会加入很多自定义的参数。而系统自带的 cmd 和 powershell，在 ANSI 转义序列支持上有一个 Bug，即必须事先使用 os.system("") 之后，才能正常启用转义序列功能（c/c++ 同理）。
参考链接：
2.2 解决方案1 - 直接使用 ANSI 转义序列
1import os
2
3# 针对于 windows 系统的处理
4if os.name == "nt":
5 os.system("")
6
7print('\033[1;32m' + 'green' + '\033[0m')
2.3 解决方案2 - 第三方包 colorama
第三方包 colorama 的原理是，对于类 Unix 系统，直接使用转义序列达到彩色输出文字；对于 Windows 系统，会使用底层的系统调用来实现彩色化文字。
详细可见：
3. 示例：彩色字符处理类
这里封装了一个类，用于处理字符串，装饰 ANSI 转义序列：
1import os
2
3
4class ColorLogDecorator:
5 """
6 class: ColorLogDecorator
7 Desc: ues for decorate the string with ANSI escape code (color function)
8
9 class_var:
10 __IS_ACTIVE: whether the decorate func active
11 __DEFAULT_STYLE: the default style for a color selected
12 __END_CODE: the end escape code
13 """
14
15 __IS_ACTIVE: bool = False
16 __DEFAULT_STYLE: str = "normal"
17 __COLOR_CODE: dict = {
18 "red": {
19 "normal": "\033[31m",
20 "strong": "\033[1;31m",
21 "bg": "\033[0;37;41m",
22 "bg-strong": "\033[1;37;41m",
23 },
24 "green": {
25 "normal": "\033[32m",
26 "strong": "\033[1;32m",
27 "bg": "\033[0;37;42m",
28 "bg-strong": "\033[1;37;42m",
29 },
30 "yellow": {
31 "normal": "\033[33m",
32 "strong": "\033[1;33m",
33 "bg": "\033[0;30;43m",
34 "bg-strong": "\033[1;30;43m",
35 },
36 "blue": {
37 "normal": "\033[34m",
38 "strong": "\033[1;34m",
39 "bg": "\033[0;37;44m",
40 "bg-strong": "\033[1;37;44m",
41 },
42 "black": {
43 "normal": "\033[30m",
44 "strong": "\033[1;30m",
45 "bg": "\033[0;37;40m",
46 "bg-strong": "\033[1;37;40m",
47 },
48 "white": {
49 "normal": "\033[37m",
50 "strong": "\033[1;37;0m",
51 "bg": "\033[0;30;47m",
52 "bg-strong": "\033[1;30;47m",
53 }
54 }
55 __END_CODE: str = "\033[0m"
56
57 @classmethod
58 def active(cls) -> None:
59 """
60 active the color decorate function
61 it will use a special menthol for windows os
62 :return: None
63 """
64 cls.__IS_ACTIVE = True
65 if os.name == "nt":
66 os.system("")
67
68 @classmethod
69 def deactivate(cls) -> None:
70 """
71 deactivate the color decorate function
72 :return: None
73 """
74 cls.__IS_ACTIVE = False
75
76 @classmethod
77 def __msg_decorator(cls, msg: str, color: str, style: str) -> str:
78 """
79 use to decorate the msg str with special style color escape code
80 :param msg: the msg str
81 :param color: the color str to select
82 :param style: the style str to select
83 :return: decorated str
84 """
85 if not cls.__IS_ACTIVE:
86 return msg
87
88 style_selected: str = cls.__DEFAULT_STYLE if style.lower() not in cls.__COLOR_CODE[color].keys() \
89 else style.lower()
90
91 return cls.__COLOR_CODE[color][style_selected] + msg + cls.__END_CODE
92
93 @classmethod
94 def red(cls, msg: str, style: str = "normal") -> str:
95 """
96 red log str
97 :param msg: the msg str
98 :param style: the style to select
99 :return: decorated str
100 """
101 return cls.__msg_decorator(msg, "red", style)
102
103 @classmethod
104 def green(cls, msg: str, style: str = "normal") -> str:
105 """
106 green log str
107 :param msg: the msg str
108 :param style: the style to select
109 :return: decorated str
110 """
111 return cls.__msg_decorator(msg, "green", style)
112
113 @classmethod
114 def yellow(cls, msg: str, style: str = "normal") -> str:
115 """
116 yellow log str
117 :param msg: the msg str
118 :param style: the style to select
119 :return: decorated str
120 """
121 return cls.__msg_decorator(msg, "yellow", style)
122
123 @classmethod
124 def blue(cls, msg: str, style: str = "normal") -> str:
125 """
126 blue log str
127 :param msg: the msg str
128 :param style: the style to select
129 :return: decorated str
130 """
131 return cls.__msg_decorator(msg, "blue", style)
132
133 @classmethod
134 def black(cls, msg: str, style: str = "normal") -> str:
135 """
136 black log str
137 :param msg: the msg str
138 :param style: the style to select
139 :return: decorated str
140 """
141 return cls.__msg_decorator(msg, "black", style)
142
143 @classmethod
144 def white(cls, msg: str, style: str = "normal") -> str:
145 """
146 white log str
147 :param msg: the msg str
148 :param style: the style to select
149 :return: decorated str
150 """
151 return cls.__msg_decorator(msg, "white", style)
152
153
154if __name__ == "__main__":
155 ColorLogDecorator.active()
156 s1: str = ColorLogDecorator.red("red") + " " + \
157 ColorLogDecorator.red("strong", "strong") + " " + \
158 ColorLogDecorator.red("bg", "bg") + " " + \
159 ColorLogDecorator.red("bg-strong", "bg-strong") + " " + \
160 ColorLogDecorator.red("other", "other")
161
162 s2: str = ColorLogDecorator.green("green") + " " + \
163 ColorLogDecorator.green("strong", "strong") + " " + \
164 ColorLogDecorator.green("bg", "bg") + " " + \
165 ColorLogDecorator.green("bg-strong", "bg-strong") + " " + \
166 ColorLogDecorator.green("other", "other")
167
168 s3: str = ColorLogDecorator.yellow("yellow") + " " + \
169 ColorLogDecorator.yellow("strong", "strong") + " " + \
170 ColorLogDecorator.yellow("bg", "bg") + " " + \
171 ColorLogDecorator.yellow("bg-strong", "bg-strong") + " " + \
172 ColorLogDecorator.yellow("other", "other")
173
174 s4: str = ColorLogDecorator.blue("blue") + " " + \
175 ColorLogDecorator.blue("strong", "strong") + " " + \
176 ColorLogDecorator.blue("bg", "bg") + " " + \
177 ColorLogDecorator.blue("bg-strong", "bg-strong") + " " + \
178 ColorLogDecorator.blue("other", "other")
179
180 s5: str = ColorLogDecorator.black("black") + " " + \
181 ColorLogDecorator.black("strong", "strong") + " " + \
182 ColorLogDecorator.black("bg", "bg") + " " + \
183 ColorLogDecorator.black("bg-strong", "bg-strong") + " " + \
184 ColorLogDecorator.black("other", "other")
185
186 s6: str = ColorLogDecorator.white("white") + " " + \
187 ColorLogDecorator.white("strong", "strong") + " " + \
188 ColorLogDecorator.white("bg", "bg") + " " + \
189 ColorLogDecorator.white("bg-strong", "bg-strong") + " " + \
190 ColorLogDecorator.white("other", "other")
191
192 print(s1)
193 print(s2)
194 print(s3)
195 print(s4)
196 print(s5)
197 print(s6)
运行结果：
其他参考链接
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