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在java 編程中,很多配置文件用鍵值對的方式存儲在 properties 文件中,可以讀取,修改。而且在java 中有 java.util.Properties 這個類,可以很方便的處理properties 文件, 在python 中雖然也有讀取配置文件的類ConfigParser, 但如果習慣java 編程的人估計更喜歡下面這個用python 實現的讀取 properties 文件的類:
""" A Python replacement for java.util.Properties class This is modelled as closely as possible to the Java original. """ import sys,os import re import time class IllegalArgumentException(Exception): def __init__(self, lineno, msg): self.lineno = lineno self.msg = msg def __str__(self): s='Exception at line number %d => %s' % (self.lineno, self.msg) return s class Properties(object): """ A Python replacement for java.util.Properties """ def __init__(self, props=None): # Note: We don't take a default properties object # as argument yet # Dictionary of properties. self._props = {} # Dictionary of properties with 'pristine' keys # This is used for dumping the properties to a file # using the 'store' method self._origprops = {} # Dictionary mapping keys from property # dictionary to pristine dictionary self._keymap = {} self.othercharre = re.compile(r'(?<!\\)(\s*\=)|(?<!\\)(\s*\:)') self.othercharre2 = re.compile(r'(\s*\=)|(\s*\:)') self.bspacere = re.compile(r'\\(?!\s$)') def __str__(self): s='{' for key,value in self._props.items(): s = ''.join((s,key,'=',value,', ')) s=''.join((s[:-2],'}')) return s def __parse(self, lines): """ Parse a list of lines and create an internal property dictionary """ # Every line in the file must consist of either a comment # or a key-value pair. A key-value pair is a line consisting # of a key which is a combination of non-white space characters # The separator character between key-value pairs is a '=', # ':' or a whitespace character not including the newline. # If the '=' or ':' characters are found, in the line, even # keys containing whitespace chars are allowed. # A line with only a key according to the rules above is also # fine. In such case, the value is considered as the empty string. # In order to include characters '=' or ':' in a key or value, # they have to be properly escaped using the backslash character. # Some examples of valid key-value pairs: # # key value # key=value # key:value # key value1,value2,value3 # key value1,value2,value3 \ # value4, value5 # key # This key= this value # key = value1 value2 value3 # Any line that starts with a '#' is considerered a comment # and skipped. Also any trailing or preceding whitespaces # are removed from the key/value. # This is a line parser. It parses the # contents like by line. lineno=0 i = iter(lines) for line in i: lineno += 1 line = line.strip() # Skip null lines if not line: continue # Skip lines which are comments if line[0] == '#': continue # Some flags escaped=False # Position of first separation char sepidx = -1 # A flag for performing wspace re check flag = 0 # Check for valid space separation # First obtain the max index to which we # can search. m = self.othercharre.search(line) if m: first, last = m.span() start, end = 0, first flag = 1 wspacere = re.compile(r'(?<![\\\=\:])(\s)') else: if self.othercharre2.search(line): # Check if either '=' or ':' is present # in the line. If they are then it means # they are preceded by a backslash. # This means, we need to modify the # wspacere a bit, not to look for # : or = characters. wspacere = re.compile(r'(?<![\\])(\s)') start, end = 0, len(line) m2 = wspacere.search(line, start, end) if m2: # print 'Space match=>',line # Means we need to split by space. first, last = m2.span() sepidx = first elif m: # print 'Other match=>',line # No matching wspace char found, need # to split by either '=' or ':' first, last = m.span() sepidx = last - 1 # print line[sepidx] # If the last character is a backslash # it has to be preceded by a space in which # case the next line is read as part of the # same property while line[-1] == '\\': # Read next line nextline = i.next() nextline = nextline.strip() lineno += 1 # This line will become part of the value line = line[:-1] + nextline # Now split to key,value according to separation char if sepidx != -1: key, value = line[:sepidx], line[sepidx+1:] else: key,value = line,'' self.processPair(key, value) def processPair(self, key, value): """ Process a (key, value) pair """ oldkey = key oldvalue = value # Create key intelligently keyparts = self.bspacere.split(key) # print keyparts strippable = False lastpart = keyparts[-1] if lastpart.find('\\ ') != -1: keyparts[-1] = lastpart.replace('\\','') # If no backspace is found at the end, but empty # space is found, strip it elif lastpart and lastpart[-1] == ' ': strippable = True key = ''.join(keyparts) if strippable: key = key.strip() oldkey = oldkey.strip() oldvalue = self.unescape(oldvalue) value = self.unescape(value) self._props[key] = value.strip() # Check if an entry exists in pristine keys if self._keymap.has_key(key): oldkey = self._keymap.get(key) self._origprops[oldkey] = oldvalue.strip() else: self._origprops[oldkey] = oldvalue.strip() # Store entry in keymap self._keymap[key] = oldkey def escape(self, value): # Java escapes the '=' and ':' in the value # string with backslashes in the store method. # So let us do the same. newvalue = value.replace(':','\:') newvalue = newvalue.replace('=','\=') return newvalue def unescape(self, value): # Reverse of escape newvalue = value.replace('\:',':') newvalue = newvalue.replace('\=','=') return newvalue def load(self, stream): """ Load properties from an open file stream """ # For the time being only accept file input streams if type(stream) is not file: raise TypeError,'Argument should be a file object!' # Check for the opened mode if stream.mode != 'r': raise ValueError,'Stream should be opened in read-only mode!' try: lines = stream.readlines() self.__parse(lines) except IOError, e: raise def getProperty(self, key): """ Return a property for the given key """ return self._props.get(key,'') def setProperty(self, key, value): """ Set the property for the given key """ if type(key) is str and type(value) is str: self.processPair(key, value) else: raise TypeError,'both key and value should be strings!' def propertyNames(self): """ Return an iterator over all the keys of the property dictionary, i.e the names of the properties """ return self._props.keys() def list(self, out=sys.stdout): """ Prints a listing of the properties to the stream 'out' which defaults to the standard output """ out.write('-- listing properties --\n') for key,value in self._props.items(): out.write(''.join((key,'=',value,'\n'))) def store(self, out, header=""): """ Write the properties list to the stream 'out' along with the optional 'header' """ if out.mode[0] != 'w': raise ValueError,'Steam should be opened in write mode!' try: out.write(''.join(('#',header,'\n'))) # Write timestamp tstamp = time.strftime('%a %b %d %H:%M:%S %Z %Y', time.localtime()) out.write(''.join(('#',tstamp,'\n'))) # Write properties from the pristine dictionary for prop, val in self._origprops.items(): out.write(''.join((prop,'=',self.escape(val),'\n'))) out.close() except IOError, e: raise def getPropertyDict(self): return self._props def __getitem__(self, name): """ To support direct dictionary like access """ return self.getProperty(name) def __setitem__(self, name, value): """ To support direct dictionary like access """ self.setProperty(name, value) def __getattr__(self, name): """ For attributes not found in self, redirect to the properties dictionary """ try: return self.__dict__[name] except KeyError: if hasattr(self._props,name): return getattr(self._props, name) if __name__=="__main__": p = Properties() p.load(open('test2.properties')) p.list() print p print p.items() print p['name3'] p['name3'] = 'changed = value' print p['name3'] p['new key'] = 'new value' p.store(open('test2.properties','w'))
當然,測試這個類你需要在程序目錄下簡歷test2.properties 文件。才可以看到效果,基本可以達到用python 讀寫 properties 文件的效果.
補充知識:python修改配置文件某個字段
思路:要修改的文件filepath
將修改后的文件寫入f2,刪除filepath,將f2名字改為filepath,從而達到修改
修改的字段可以參數化,即下面出現的 lilei 可以參數化
imort os tag=“jdbc.cubedata.username=” midifyInfo=“jdbc.cubedata.username=lilei” f1=filepath f2=application.application fileInfo=open(filepath)
以上這篇在python中修改.properties文件的操作就是小編分享給大家的全部內容了,希望能給大家一個參考,也希望大家多多支持億速云。
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