本节内容概要：
一、模块
1、configparser
2、解析xml的模块
3、subprocess
4、shutil
5、zifile
6、tarfile
二、面向对象（上）
1、封装
2、继承
一、模块
configparser
configparser用于处理特定格式的文件，其本质上是利用open来操作文件。
db #文件内容
# 注释1
; 注释2
[section1] # 节点
k1 = v1 # 值
k2:v2 # 值
[section2] # 节点
k1 = v1 # 值
##################################
import configparser
config = configparser.ConfigParser()
config.read('db',encoding='utf-8')
#获取所有节点
ret = config.sections() #['section1', 'section2']
#获取指定节点下所有的键值对
ret = config.items('section1') #[('k1', '123'), ('k2', 'v2')]
#获取指定节点下所有的建
ret = config.options('section1') #['k1', 'k2']
#获取指定节点下指定key的值
ret = config.get('section1','k1') #123
#ret = config.getint('section1','k1')
#ret = config.getfloat('section1', 'k1')
#ret = config.getboolean('section1','k4') #True
#检查、删除、添加节点
#检查
has_sec = config.has_section('section4')
print(has_sec) #False
#添加节点
config.add_section('SEC_1')
config.write(open('db','w'))
#删除节点
config.remove_section('SEC_1')
config.write('db','w')
#检查组内键值对
has_opt = config.has_option('section1','k1')
print(has_opt) #True
#删除组内键值对
config.remove_option('section1','k1')
config.write(open('db','w'))
#设置组内键值对
config.set('section1','k1','123')
config.write(open('db','w'))
浏览器返回的字符串:
a、HTML
b、Json
c、XML :
页面上做展示（字符串类型的一个XML格式数据）
配置文件（文件，内部数据XML格式）
XML是实现不同语言或程序之间进行数据交换的协议，XML文件格式如下：
<data>
<country name="Liechtenstein">
<rank updated="yes">2</rank>
<year>2023</year>
<gdppc>141100</gdppc>
<neighbor direction="E" name="Austria" />
<neighbor direction="W" name="Switzerland" />
</country>
<country name="Singapore">
<rank updated="yes">5</rank>
<year>2026</year>
<gdppc>59900</gdppc>
<neighbor direction="N" name="Malaysia" />
</country>
<country name="Panama">
<rank updated="yes">69</rank>
<year>2026</year>
<gdppc>13600</gdppc>
<neighbor direction="W" name="Costa Rica" />
<neighbor direction="E" name="Colombia" />
</country>
</data>
1、解析XML
#利用ElementTree.XML将字符串解析成xml对象
from xml.etree import ElementTree as ET # 打开文件，读取XML内容 str_xml = open('xo.xml', 'r').read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) print(root.tag) #data
#利用ElementTree.parse将文件直接解析成xml对象 from xml.etree import ElementTree as ET # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() print(root.tag) #data
2、操作XML
XML格式类型是节点嵌套节点，对于每一个节点均有以下功能，以便对当前节点进行操作：
class Element: """An XML element. This class is the reference implementation of the Element interface. An element's length is its number of subelements. That means if you want to check if an element is truly empty, you should check BOTH its length AND its text attribute. The element tag, attribute names, and attribute values can be either bytes or strings. *tag* is the element name. *attrib* is an optional dictionary containing element attributes. *extra* are additional element attributes given as keyword arguments. Example form: <tag attrib>text<child/>...</tag>tail """ 当前节点的标签名 tag = None """The element's name.""" 当前节点的属性 attrib = None """Dictionary of the element's attributes.""" 当前节点的内容 text = None """ Text before first subelement. This is either a string or the value None. Note that if there is no text, this attribute may be either None or the empty string, depending on the parser. """ tail = None """ Text after this element's end tag, but before the next sibling element's start tag. This is either a string or the value None. Note that if there was no text, this attribute may be either None or an empty string, depending on the parser. """ def __init__(self, tag, attrib={}, **extra): if not isinstance(attrib, dict): raise TypeError("attrib must be dict, not %s" % ( attrib.__class__.__name__,)) attrib = attrib.copy() attrib.update(extra) self.tag = tag self.attrib = attrib self._children = [] def __repr__(self): return "<%s %r at %#x>" % (self.__class__.__name__, self.tag, id(self)) def makeelement(self, tag, attrib): 创建一个新节点 """Create a new element with the same type. *tag* is a string containing the element name. *attrib* is a dictionary containing the element attributes. Do not call this method, use the SubElement factory function instead. """ return self.__class__(tag, attrib) def copy(self): """Return copy of current element. This creates a shallow copy. Subelements will be shared with the original tree. """ elem = self.makeelement(self.tag, self.attrib) elem.text = self.text elem.tail = self.tail elem[:] = self return elem def __len__(self): return len(self._children) def __bool__(self): warnings.warn( "The behavior of this method will change in future versions. " "Use specific 'len(elem)' or 'elem is not None' test instead.", FutureWarning, stacklevel=2 ) return len(self._children) != 0 # emulate old behaviour, for now def __getitem__(self, index): return self._children[index] def __setitem__(self, index, element): # if isinstance(index, slice): # for elt in element: # assert iselement(elt) # else: # assert iselement(element) self._children[index] = element def __delitem__(self, index): del self._children[index] def append(self, subelement): 为当前节点追加一个子节点 """Add *subelement* to the end of this element. The new element will appear in document order after the last existing subelement (or directly after the text, if it's the first subelement), but before the end tag for this element. """ self._assert_is_element(subelement) self._children.append(subelement) def extend(self, elements): 为当前节点扩展 n 个子节点 """Append subelements from a sequence. *elements* is a sequence with zero or more elements. """ for element in elements: self._assert_is_element(element) self._children.extend(elements) def insert(self, index, subelement): 在当前节点的子节点中插入某个节点，即：为当前节点创建子节点，然后插入指定位置 """Insert *subelement* at position *index*.""" self._assert_is_element(subelement) self._children.insert(index, subelement) def _assert_is_element(self, e): # Need to refer to the actual Python implementation, not the # shadowing C implementation. if not isinstance(e, _Element_Py): raise TypeError('expected an Element, not %s' % type(e).__name__) def remove(self, subelement): 在当前节点在子节点中删除某个节点 """Remove matching subelement. Unlike the find methods, this method compares elements based on identity, NOT ON tag value or contents. To remove subelements by other means, the easiest way is to use a list comprehension to select what elements to keep, and then use slice assignment to update the parent element. ValueError is raised if a matching element could not be found. """ # assert iselement(element) self._children.remove(subelement) def getchildren(self): 获取所有的子节点（废弃） """(Deprecated) Return all subelements. Elements are returned in document order. """ warnings.warn( "This method will be removed in future versions. " "Use 'list(elem)' or iteration over elem instead.", DeprecationWarning, stacklevel=2 ) return self._children def find(self, path, namespaces=None): 获取第一个寻找到的子节点 """Find first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return the first matching element, or None if no element was found. """ return ElementPath.find(self, path, namespaces) def findtext(self, path, default=None, namespaces=None): 获取第一个寻找到的子节点的内容 """Find text for first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *default* is the value to return if the element was not found, *namespaces* is an optional mapping from namespace prefix to full name. Return text content of first matching element, or default value if none was found. Note that if an element is found having no text content, the empty string is returned. """ return ElementPath.findtext(self, path, default, namespaces) def findall(self, path, namespaces=None): 获取所有的子节点 """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Returns list containing all matching elements in document order. """ return ElementPath.findall(self, path, namespaces) def iterfind(self, path, namespaces=None): 获取所有指定的节点，并创建一个迭代器（可以被for循环） """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return an iterable yielding all matching elements in document order. """ return ElementPath.iterfind(self, path, namespaces) def clear(self): 清空节点 """Reset element. This function removes all subelements, clears all attributes, and sets the text and tail attributes to None. """ self.attrib.clear() self._children = [] self.text = self.tail = None def get(self, key, default=None): 获取当前节点的属性值 """Get element attribute. Equivalent to attrib.get, but some implementations may handle this a bit more efficiently. *key* is what attribute to look for, and *default* is what to return if the attribute was not found. Returns a string containing the attribute value, or the default if attribute was not found. """ return self.attrib.get(key, default) def set(self, key, value): 为当前节点设置属性值 """Set element attribute. Equivalent to attrib[key] = value, but some implementations may handle this a bit more efficiently. *key* is what attribute to set, and *value* is the attribute value to set it to. """ self.attrib[key] = value def keys(self): 获取当前节点的所有属性的 key """Get list of attribute names. Names are returned in an arbitrary order, just like an ordinary Python dict. Equivalent to attrib.keys() """ return self.attrib.keys() def items(self): 获取当前节点的所有属性值，每个属性都是一个键值对 """Get element attributes as a sequence. The attributes are returned in arbitrary order. Equivalent to attrib.items(). Return a list of (name, value) tuples. """ return self.attrib.items() def iter(self, tag=None): 在当前节点的子孙中根据节点名称寻找所有指定的节点，并返回一个迭代器（可以被for循环）。 """Create tree iterator. The iterator loops over the element and all subelements in document order, returning all elements with a matching tag. If the tree structure is modified during iteration, new or removed elements may or may not be included. To get a stable set, use the list() function on the iterator, and loop over the resulting list. *tag* is what tags to look for (default is to return all elements) Return an iterator containing all the matching elements. """ if tag == "*": tag = None if tag is None or self.tag == tag: yield self for e in self._children: yield from e.iter(tag) # compatibility def getiterator(self, tag=None): # Change for a DeprecationWarning in 1.4 warnings.warn( "This method will be removed in future versions. " "Use 'elem.iter()' or 'list(elem.iter())' instead.", PendingDeprecationWarning, stacklevel=2 ) return list(self.iter(tag)) def itertext(self): 在当前节点的子孙中根据节点名称寻找所有指定的节点的内容，并返回一个迭代器（可以被for循环）。 """Create text iterator. The iterator loops over the element and all subelements in document order, returning all inner text. """ tag = self.tag if not isinstance(tag, str) and tag is not None: return if self.text: yield self.text for e in self: yield from e.itertext() if e.tail: yield e.tail
由于 每个节点 都具有以上的方法，并且在上一步骤中解析时均得到了root（xml文件的根节点），so 可以利用以上方法进行操作xml文件。
a. 遍历XML文档的所有内容
from xml.etree import ElementTree as ET ############ 解析方式一 ############ """ # 打开文件，读取XML内容 str_xml = open('xo.xml', 'r').read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) """ ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ### 操作 # 顶层标签 print(root.tag) # 遍历XML文档的第二层 for child in root: # 第二层节点的标签名称和标签属性 print(child.tag, child.attrib) # 遍历XML文档的第三层 for i in child: # 第二层节点的标签名称和内容 print(i.tag,i.text)
b、遍历XML中指定的节点
from xml.etree import ElementTree as ET ############ 解析方式一 ############ """ # 打开文件，读取XML内容 str_xml = open('xo.xml', 'r').read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) """ ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ### 操作 # 顶层标签 print(root.tag) # 遍历XML中所有的year节点 for node in root.iter('year'): # 节点的标签名称和内容 print(node.tag, node.text)
c、修改节点内容
由于修改的节点时，均是在内存中进行，其不会影响文件中的内容。所以，如果想要修改，则需要重新将内存中的内容写到文件。
from xml.etree import ElementTree as ET ############ 解析方式一 ############ # 打开文件，读取XML内容 str_xml = open('xo.xml', 'r').read() # 将字符串解析成xml特殊对象，root代指xml文件的根节点 root = ET.XML(str_xml) ############ 操作 ############ # 顶层标签 print(root.tag) # 循环所有的year节点 for node in root.iter('year'): # 将year节点中的内容自增一 new_year = int(node.text) + 1 node.text = str(new_year) # 设置属性 node.set('name', 'alex') node.set('age', '18') # 删除属性 del node.attrib['name'] ############ 保存文件 ############ tree = ET.ElementTree(root) tree.write("newnew.xml", encoding='utf-8')
from xml.etree import ElementTree as ET ############ 解析方式二 ############ # 直接解析xml文件 tree = ET.parse("xo.xml") # 获取xml文件的根节点 root = tree.getroot() ############ 操作 ############ # 顶层标签 print(root.tag) # 循环所有的year节点 for node in root.iter('year'): # 将year节点中的内容自增一 new_year = int(node.text) + 1 node.text = str(new_year) # 设置属性 node.set('name', 'alex') node.set('age', '18') # 删除属性 del node.attrib['name'] ############ 保存文件 ############ tree.write("newnew.xml", encoding='utf-8')
d、删除节点
from xml.etree import ElementTree as ET # 创建根节点 root = ET.Element("famliy") # 创建节点大儿子 son1 = ET.Element('son', {'name': '儿1'}) # 创建小儿子 son2 = ET.Element('son', {"name": '儿2'}) # 在大儿子中创建两个孙子 grandson1 = ET.Element('grandson', {'name': '儿11'}) grandson2 = ET.Element('grandson', {'name': '儿12'}) son1.append(grandson1) son1.append(grandson2) # 把儿子添加到根节点中 root.append(son1) root.append(son1) tree = ET.ElementTree(root) tree.write('oooo.xml',encoding='utf-8', short_empty_elements=False)
from xml.etree import ElementTree as ET # 创建根节点 root = ET.Element("famliy") # 创建大儿子 # son1 = ET.Element('son', {'name': '儿1'}) son1 = root.makeelement('son', {'name': '儿1'}) # 创建小儿子 # son2 = ET.Element('son', {"name": '儿2'}) son2 = root.makeelement('son', {"name": '儿2'}) # 在大儿子中创建两个孙子 # grandson1 = ET.Element('grandson', {'name': '儿11'}) grandson1 = son1.makeelement('grandson', {'name': '儿11'}) # grandson2 = ET.Element('grandson', {'name': '儿12'}) grandson2 = son1.makeelement('grandson', {'name': '儿12'}) son1.append(grandson1) son1.append(grandson2) # 把儿子添加到根节点中 root.append(son1) root.append(son1) tree = ET.ElementTree(root) tree.write('oooo.xml',encoding='utf-8', short_empty_elements=False)
from xml.etree import ElementTree as ET # 创建根节点 root = ET.Element("famliy") # 创建节点大儿子 son1 = ET.SubElement(root, "son", attrib={'name': '儿1'}) # 创建小儿子 son2 = ET.SubElement(root, "son", attrib={"name": "儿2"}) # 在大儿子中创建一个孙子 grandson1 = ET.SubElement(son1, "age", attrib={'name': '儿11'}) grandson1.text = '孙子' et = ET.ElementTree(root) #生成文档对象 et.write("test.xml", encoding="utf-8", xml_declaration=True, short_empty_elements=False)
由于原生保存的XML时默认无缩进，如果想要设置缩进的话， 需要修改保存方式：
from xml.etree import ElementTree as ET from xml.dom import minidom def prettify(elem): """将节点转换成字符串，并添加缩进。 """ rough_string = ET.tostring(elem, 'utf-8') reparsed = minidom.parseString(rough_string) return reparsed.toprettyxml(indent="\t") # 创建根节点 root = ET.Element("famliy") # 创建大儿子 # son1 = ET.Element('son', {'name': '儿1'}) son1 = root.makeelement('son', {'name': '儿1'}) # 创建小儿子 # son2 = ET.Element('son', {"name": '儿2'}) son2 = root.makeelement('son', {"name": '儿2'}) # 在大儿子中创建两个孙子 # grandson1 = ET.Element('grandson', {'name': '儿11'}) grandson1 = son1.makeelement('grandson', {'name': '儿11'}) # grandson2 = ET.Element('grandson', {'name': '儿12'}) grandson2 = son1.makeelement('grandson', {'name': '儿12'}) son1.append(grandson1) son1.append(grandson2) # 把儿子添加到根节点中 root.append(son1) root.append(son1) raw_str = prettify(root) f = open("xxxoo.xml",'w',encoding='utf-8') f.write(raw_str) f.close()
4、命名空间
详细介绍：http://www.w3school.com.cn/xml/xml_namespaces.asp
from xml.etree import ElementTree as ET ET.register_namespace('com',"http://www.company.com") #some name # build a tree structure root = ET.Element("{http://www.company.com}STUFF") body = ET.SubElement(root, "{http://www.company.com}MORE_STUFF", attrib={"{http://www.company.com}hhh": "123"}) body.text = "STUFF EVERYWHERE!" # wrap it in an ElementTree instance, and save as XML tree = ET.ElementTree(root) tree.write("page.xml", xml_declaration=True, encoding='utf-8', method="xml")
系统命令
可以执行shell命令的相关模块和函数有：
- os.system
- os.spawn*
- os.popen* --废弃
- popen2.* --废弃
- commands.* --废弃，3.x中被移除
以上执行shell命令的相关的模块和函数的功能均在 subprocess 模块中实现，并提供了更丰富的功能。
subprocess.call
执行命令，返回状态码
ret = subprocess.call(["ls", "-l"], shell=False) #等于False就以列表形式写命令
ret = subprocess.call("ls -l", shell=True)
subprocess.check_call
执行命令，如果执行状态码是 0 ，则返回0，否则抛异常
subprocess.check_call(["ls", "-l"])
subprocess.check_call("exit 1", shell=True)
subprocess.check_output
执行命令，如果状态码是 0 ，则返回执行结果，否则抛异常
subprocess.check_output(["echo", "Hello World!"])
subprocess.check_output("exit 1", shell=True)
subprocess.Popen(...)
用于执行复杂的系统命令
参数：
- args：shell命令，可以是字符串或者序列类型（如：list，元组）
- bufsize：指定缓冲。0 无缓冲,1 行缓冲,其他 缓冲区大小,负值 系统缓冲
- stdin, stdout, stderr：分别表示程序的标准输入、输出、错误句柄
- preexec_fn：只在Unix平台下有效，用于指定一个可执行对象（callable object），它将在子进程运行之前被调用
- close_sfs：在windows平台下，如果close_fds被设置为True，则新创建的子进程将不会继承父进程的输入、输出、错误管道。
所以不能将close_fds设置为True同时重定向子进程的标准输入、输出与错误(stdin, stdout, stderr)。 - shell：同上
- cwd：用于设置子进程的当前目录
- env：用于指定子进程的环境变量。如果env = None，子进程的环境变量将从父进程中继承。
- universal_newlines：不同系统的换行符不同，True -> 同意使用 \n
- startupinfo与createionflags只在windows下有效
将被传递给底层的CreateProcess()函数，用于设置子进程的一些属性，如：主窗口的外观，进程的优先级等等
import subprocess
ret1 = subprocess.Popen(["mkdir","t1"])
ret2 = subprocess.Popen("mkdir t2", shell=True)
终端输入的命令分为两种：
- 输入即可得到输出，如：ifconfig
- 输入进行某环境，依赖再输入，如：python
import subprocess
obj = subprocess.Popen("mkdir t3", shell=True, cwd='/home/dev',)
import subprocess
obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
obj.stdin.write("print(1)\n")
obj.stdin.write("print(2)")
obj.stdin.close()
cmd_out = obj.stdout.read()
obj.stdout.close()
cmd_error = obj.stderr.read()
obj.stderr.close()
print(cmd_out)
print(cmd_error)
import subprocess
obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
obj.stdin.write("print(1)\n")
obj.stdin.write("print(2)")
out_error_list = obj.communicate()
print(out_error_list)
import subprocess
obj = subprocess.Popen(["python"], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
out_error_list = obj.communicate('print("hello")')
print(out_error_list)
shutil
高级的 文件、文件夹、压缩包 处理模块
shutil.copyfileobj(fsrc, fdst[, length])
将文件内容拷贝到另一个文件中
import shutil
shutil.copyfileobj(open('old.xml','r'), open('new.xml', 'w'))
shutil.copyfile(src, dst)
拷贝文件
shutil.copyfile('f1.log', 'f2.log')
shutil.copymode(src, dst)
仅拷贝权限。内容、组、用户均不变
shutil.copymode('f1.log', 'f2.log')
shutil.copystat(src, dst)
仅拷贝状态的信息，包括：mode bits, atime, mtime, flags
shutil.copystat('f1.log', 'f2.log')
shutil.copy(src, dst)
拷贝文件和权限
import shutil
shutil.copy('f1.log', 'f2.log')
shutil.copy2(src, dst)
拷贝文件和状态信息
import shutil
shutil.copy2('f1.log', 'f2.log')
shutil.ignore_patterns(*patterns)
shutil.copytree(src, dst, symlinks=False, ignore=None)
递归的去拷贝文件夹
import shutil
shutil.copytree('folder1', 'folder2', ignore=shutil.ignore_patterns('*.pyc', 'tmp*'))
import shutil
shutil.copytree('f1', 'f2', symlinks=True, ignore=shutil.ignore_patterns('*.pyc', 'tmp*'))
shutil.rmtree(path[, ignore_errors[, onerror]])
递归的去删除文件
import shutil
shutil.rmtree('folder1')
shutil.move(src, dst)
递归的去移动文件，它类似mv命令，其实就是重命名。
import shutil
shutil.move('folder1', 'folder3')
shutil.make_archive(base_name, format,...)
创建压缩包并返回文件路径，例如：zip、tar
创建压缩包并返回文件路径，例如：zip、tar
- base_name： 压缩包的文件名，也可以是压缩包的路径。只是文件名时，则保存至当前目录，否则保存至指定路径，
如：www =>保存至当前路径
如：/Users/wupeiqi/www =>保存至/Users/wupeiqi/ - format： 压缩包种类，“zip”, “tar”, “bztar”，“gztar”
- root_dir： 要压缩的文件夹路径（默认当前目录）
- owner： 用户，默认当前用户
- group： 组，默认当前组
- logger： 用于记录日志，通常是logging.Logger对象
#将 /Users/wupeiqi/Downloads/test 下的文件打包放置当前程序目录
import shutil
ret = shutil.make_archive("wwwwwwwwww", 'gztar', root_dir='/Users/wupeiqi/Downloads/test')
#将 /Users/wupeiqi/Downloads/test 下的文件打包放置 /Users/wupeiqi/目录
import shutil
ret = shutil.make_archive("/Users/wupeiqi/wwwwwwwwww", 'gztar', root_dir='/Users/wupeiqi/Downloads/test')
shutil 对压缩包的处理是调用 ZipFile 和 TarFile 两个模块来进行的，详细：
zipfile
import zipfile # 压缩 z = zipfile.ZipFile('laxi.zip', 'w') z.write('a.log') z.write('data.data') z.close() # 解压 z = zipfile.ZipFile('laxi.zip', 'r') z.extractall() z.close() #########一些方法##################### import zipfile # z = zipfile.ZipFile('111.zip','r') z.write('a.log') z.write('b.log') z.close() print(z.namelist()) #['a.log', 'b.log'] z.extract('a.log')
tarfile
import tarfile # 压缩 tar = tarfile.open('your.tar','w') tar.add('/Users/wupeiqi/PycharmProjects/bbs2.log', arcname='bbs2.log') tar.add('/Users/wupeiqi/PycharmProjects/cmdb.log', arcname='cmdb.log') tar.close() # 解压 tar = tarfile.open('your.tar','r') tar.extractall() # 可设置解压地址 tar.close() ############一些方法################## import tarfile tar = tarfile.open('222.tar','w') tar.add('a.log',arcname='c.log') tar.close() tar = tarfile.open('222.tar','r') print(tar.getnames()) z = tar.getmember('c.log') #找到这个对象 传给tar tar.extract(z) #传给tar解压出来 tar.getmembers() #把每个文件的格式打印出来
二、面向对象（上）
1、python 函数式+面向对象
2、函数式编程，面向对象编程实现： 发送邮件的功能
def mail(email,message): print("去发吧") return True mail("sdfs@qq.com","好人")
class Foo: #方法（函数放在类里叫方法） def mail(self,email,message): #函数写在类里，必须要加self print("去发吧") return True
调用：：
a、创建对象，类名后面加()
obj = Foo()
b、通过对象去执行方法
obj.mail("sdfs@qq.com","好人")
类和对象
a.创建类
class 类名
def 方法名（self,xxxx）#函数放在类里叫方法
pass
b.创建对象
对象 = 类名()
c.通过对象执行方法
对象.方法名()
def fetch(host,username,password,sql): pass def create(host,username,password,sql): pass def remove(host,username,password,id): pass def modify(host,username,password,name): pass
class SQLhelper: def fetch(host, username, password, sql): pass def create(host,username,password,sql): pass def remove(host,username,password,id): pass def modify(host,username,password,name): pass obj = SQLhelper() obj.fetch()
什么时候用面向对象？当某一些函数具有相同参数时，可以使用面向对象的方式，将参数值一次性的封装到对象，以后去对象里面取值
class SQLhelper: def fetch(self, sql): print(sql) def create(self,sql): pass def remove(self,id): pass def modify(self, name): #obj 就是self pass obj = SQLhelper() obj.hhost = "sdf1.com" obj.uusername = "QL" obj.pwd = "123" obj.fetch("select* from A") # obj2 = SQLhelper() # obj2.hhost = "sdf2.com" # obj2.uusername = "Alex" # obj2.pwd = "123" # obj2.fetch("select* from A")
self是什么鬼？
self 是一个python自动会给传值的参数
哪个对象执行方法，self就是谁
obj.fetch('selec...') self = obj
obj2.fetch('selec...') self = obj2
类中有一个特殊的方法__init__,类()自动被执行称为：构造方法
class SQLhelper: def __init__(self,a1,a2,a3): #obj1 = SQLhelper() 加括号就自动执行__init__ print("自动执行init") #obj = SQLhelper('c1.com','','') self.hhost = a1 self.uuser = a2 self.pwd = a3 def fetch(self, sql): print(sql) def create(self,sql): pass def remove(self,id): pass def modify(self, name): #obj 就是self pass obj = SQLhelper('c1.com','QL','123')
三大特性：封装、继承、多态
封装：
class c1: def __init__(self,name,obj): #obj =c2 self.name = name self.obj = obj #self.obj = c2 ,c2里有age可取 self.obj.age class c2: def __init__(self,name,age): self.name = name self.age = age def show(self): print(self.name) return 11 class c3: def __init__(self,a1): self.money = 123 self.aaa = a1 c2_obj = c2('aa',11) #c2_obj是c2类型 # - name = "aa" # - age = 11 c1_obj = c1('alex',c2_obj) #c1_obj是c1类型 # - name = "alex" # - obj = c2_obj #print(c1_obj.obj.age) c3_obj = c3(c1_obj) # - money # - aaa #使用c3_obj执行c2_obj的方法 #print(c3_obj.aaa.obj.name) #使用c3_obj执行show方法 print(c3_obj.aaa.obj.show())
继承：
可以多继承
class F1: #F1就是F2的父类，或叫基类 def show(self): print('show') class F2(F1): #相当于把F1里的show方法写在了F2里，F2叫子类，或派生类, def bar(self): # print('bar') class F3(F2): pass
优先执行自己的方法：包括__init__方法
class F1:
def show(self):
print('show')
def foo(self):
print(self.name)
class F2(F1):
def __init__(self,name):
self.name = name
def bar(self): #
print('bar')
def show(self): #F1里也有show方法，优先执行自己的，包括init方法。
print("F2.show")
obj = F2('alex')
obj.show()
obj.foo()
每次碰到self都回到起点去找，子类没有去父类找
class s1:
def F1(self):
self.F2() #self = obj = s2 每次碰到self都回到起点去找，子类没有去父类找
def F2(self):
pass
class s2(s1):
def F3(self):
self.F1()
def F2(self):
pass
obj = s2()
obj.F3() #执行s2.F2
obj = s1()
obj.F1() #执行s1.F2
多继承
class c1:
def f1(self):
pass
def f2(self):
pass
class c2:
def f2(self):
pass
class c3(c2,c1): #c2在前面，所以优先级高，现找 c2再找c1
def f3(self):
pass
obj = c3()
obj.f2() #执行c2.f2
继承套继承
class c0:
def f2(self):
print('c0')
class c1(c0):
def f1(self):
print('c1')
class c2:
def f2(self):
print(c2)
class c3(c2,c1): #c2在前面，所以优先级高
def f3(self):
print('c3')
obj = c3()
obj.f2() #从左往上找
嵌套三层继承
class c_2:
def f2(self):
print('c-2')
class c_1:
def f1(self):
print('c-1')
class c0:
def f1(self):
print('c0')
class c1(c0):
def f1(self):
print('c1')
class c2(c_1):
def f2(self):
print('c2')
class c3(c2,c1): #c2在前面，所以优先级高
def f3(self):
print('c3')
obj = c3()
obj.f2() #当c3继承的c1和c2有共同的父类c_2，先从c1往上找，找完c1，找c0,然后从c2往上找，然后找c_1,最后找到共同的父类c_2
