python文件操作字符串转码

Posted 2021-03-14 ^_^

文件操作

对文件操作流程

1. 打开文件，得到文件句柄并赋值给一个变量
2. 通过句柄对文件进行操作
3. 关闭文件 

现有文件如下 

 1 Somehow, it seems the love I knew was always the most destructive kind
 2 不知为何，我经历的爱情总是最具毁灭性的的那种
 3 Yesterday when I was young
 4 昨日当我年少轻狂
 5 The taste of life was sweet
 6 生命的滋味是甜的
 7 As rain upon my tongue
 8 就如舌尖上的雨露
 9 I teased at life as if it were a foolish game
10 我戏弄生命 视其为愚蠢的游戏
11 The way the evening breeze
12 就如夜晚的微风
13 May tease the candle flame
14 逗弄蜡烛的火苗
15 The thousand dreams I dreamed
16 我曾千万次梦见
17 The splendid things I planned
18 那些我计划的绚丽蓝图
19 I always built to last on weak and shifting sand
20 但我总是将之建筑在易逝的流沙上
21 I lived by night and shunned the naked light of day
22 我夜夜笙歌 逃避白昼赤裸的阳光
23 And only now I see how the time ran away
24 事到如今我才看清岁月是如何匆匆流逝
25 Yesterday when I was young
26 昨日当我年少轻狂
27 So many lovely songs were waiting to be sung
28 有那么多甜美的曲儿等我歌唱
29 So many wild pleasures lay in store for me
30 有那么多肆意的快乐等我享受
31 And so much pain my eyes refused to see
32 还有那么多痛苦 我的双眼却视而不见
33 I ran so fast that time and youth at last ran out
34 我飞快地奔走 最终时光与青春消逝殆尽
35 I never stopped to think what life was all about
36 我从未停下脚步去思考生命的意义
37 And every conversation that I can now recall
38 如今回想起的所有对话
39 Concerned itself with me and nothing else at all
40 除了和我相关的 什么都记不得了
41 The game of love I played with arrogance and pride
42 我用自负和傲慢玩着爱情的游戏
43 And every flame I lit too quickly, quickly died
44 所有我点燃的火焰都熄灭得太快
45 The friends I made all somehow seemed to slip away
46 所有我交的朋友似乎都不知不觉地离开了
47 And only now I\'m left alone to end the play, yeah
48 只剩我一个人在台上来结束这场闹剧
49 Oh, yesterday when I was young
50 噢 昨日当我年少轻狂
51 So many, many songs were waiting to be sung
52 有那么那么多甜美的曲儿等我歌唱
53 So many wild pleasures lay in store for me
54 有那么多肆意的快乐等我享受
55 And so much pain my eyes refused to see
56 还有那么多痛苦 我的双眼却视而不见
57 There are so many songs in me that won\'t be sung
58 我有太多歌曲永远不会被唱起
59 I feel the bitter taste of tears upon my tongue
60 我尝到了舌尖泪水的苦涩滋味
61 The time has come for me to pay for yesterday
62 终于到了付出代价的时间 为了昨日
63 When I was young
64 当我年少轻狂

待处理文件内容

基本操作　　

1 f = open(\'lyrics\') #打开文件
2 first_line = f.readline()
3 print(\'first line:\',first_line) #读一行
4 print(\'我是分隔线\'.center(50,\'-\'))
5 data = f.read()# 读取剩下的所有内容,文件大时不要用
6 print(data) #打印文件
7  
8 f.close() #关闭文件

打开文件的模式有：

• r，只读模式（默认）。
• w，只写模式。【不可读；不存在则创建；存在则删除内容；】
• a，追加模式。【可读；   不存在则创建；存在则只追加内容；】

"+" 表示可以同时读写某个文件

• r+，可读写文件。【可读；可写；可追加】
• w+，写读
• a+，同a

"U"表示在读取时，可以将 \\r \\n \\r\\n自动转换成 \\n （与 r 或 r+ 模式同使用）

• rU
• r+U

"b"表示处理二进制文件（如：FTP发送上传ISO镜像文件，linux可忽略，windows处理二进制文件时需标注）

• rb
• wb
• ab

其它语法

 1 def close(self): # real signature unknown; restored from __doc__
 2         """
 3         Close the file.
 4         
 5         A closed file cannot be used for further I/O operations.  close() may be
 6         called more than once without error.
 7         """
 8         pass
 9 
10     def fileno(self, *args, **kwargs): # real signature unknown
11         """ Return the underlying file descriptor (an integer). """
12         pass
13 
14     def isatty(self, *args, **kwargs): # real signature unknown
15         """ True if the file is connected to a TTY device. """
16         pass
17 
18     def read(self, size=-1): # known case of _io.FileIO.read
19         """
20         注意，不一定能全读回来
21         Read at most size bytes, returned as bytes.
22         
23         Only makes one system call, so less data may be returned than requested.
24         In non-blocking mode, returns None if no data is available.
25         Return an empty bytes object at EOF.
26         """
27         return ""
28 
29     def readable(self, *args, **kwargs): # real signature unknown
30         """ True if file was opened in a read mode. """
31         pass
32 
33     def readall(self, *args, **kwargs): # real signature unknown
34         """
35         Read all data from the file, returned as bytes.
36         
37         In non-blocking mode, returns as much as is immediately available,
38         or None if no data is available.  Return an empty bytes object at EOF.
39         """
40         pass
41 
42     def readinto(self): # real signature unknown; restored from __doc__
43         """ Same as RawIOBase.readinto(). """
44         pass #不要用,没人知道它是干嘛用的
45 
46     def seek(self, *args, **kwargs): # real signature unknown
47         """
48         Move to new file position and return the file position.
49         
50         Argument offset is a byte count.  Optional argument whence defaults to
51         SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values
52         are SEEK_CUR or 1 (move relative to current position, positive or negative),
53         and SEEK_END or 2 (move relative to end of file, usually negative, although
54         many platforms allow seeking beyond the end of a file).
55         
56         Note that not all file objects are seekable.
57         """
58         pass
59 
60     def seekable(self, *args, **kwargs): # real signature unknown
61         """ True if file supports random-access. """
62         pass
63 
64     def tell(self, *args, **kwargs): # real signature unknown
65         """
66         Current file position.
67         
68         Can raise OSError for non seekable files.
69         """
70         pass
71 
72     def truncate(self, *args, **kwargs): # real signature unknown
73         """
74         Truncate the file to at most size bytes and return the truncated size.
75         
76         Size defaults to the current file position, as returned by tell().
77         The current file position is changed to the value of size.
78         """
79         pass
80 
81     def writable(self, *args, **kwargs): # real signature unknown
82         """ True if file was opened in a write mode. """
83         pass
84 
85     def write(self, *args, **kwargs): # real signature unknown
86         """
87         Write bytes b to file, return number written.
88         
89         Only makes one system call, so not all of the data may be written.
90         The number of bytes actually written is returned.  In non-blocking mode,
91         returns None if the write would block.
92         """
93         pass

View Code

with语句

为了避免打开文件后忘记关闭，可以通过管理上下文，即：

1 with open(\'log\',\'r\') as f:
2      
3     ...

如此方式，当with代码块执行完毕时，内部会自动关闭并释放文件资源。

在Python 2.7 后，with又支持同时对多个文件的上下文进行管理，即：

1 with open(\'log1\') as obj1, open(\'log2\') as obj2:
2     pass

程序练习　　

程序1: 实现简单的shell sed替换功能

程序2:修改haproxy配置文件 

需求：

 1 1、查
 2     输入：www.oldboy.org
 3     获取当前backend下的所有记录
 4 
 5 2、新建
 6     输入：
 7         arg = {
 8             \'bakend\': \'www.oldboy.org\',
 9             \'record\':{
10                 \'server\': \'100.1.7.9\',
11                 \'weight\': 20,
12                 \'maxconn\': 30
13             }
14         }
15 
16 3、删除
17     输入：
18         arg = {
19             \'bakend\': \'www.oldboy.org\',
20             \'record\':{
21                 \'server\': \'100.1.7.9\',
22                 \'weight\': 20,
23                 \'maxconn\': 30
24             }
25         }

需求

 1 global       
 2         log 127.0.0.1 local2
 3         daemon
 4         maxconn 256
 5         log 127.0.0.1 local2 info
 6 defaults
 7         log global
 8         mode http
 9         timeout connect 5000ms
10         timeout client 50000ms
11         timeout server 50000ms
12         option  dontlognull
13 
14 listen stats :8888
15         stats enable
16         stats uri       /admin
17         stats auth      admin:1234
18 
19 frontend oldboy.org
20         bind 0.0.0.0:80
21         option httplog
22         option httpclose
23         option  forwardfor
24         log global
25         acl www hdr_reg(host) -i www.oldboy.org
26         use_backend www.oldboy.org if www
27 
28 backend www.oldboy.org
29         server 100.1.7.9 100.1.7.9 weight 20 maxconn 3000

原配置文件

字符编码与转码

详细文章:

http://www.cnblogs.com/yuanchenqi/articles/5956943.html

http://www.diveintopython3.net/strings.html