02:BeautifulSoup
1.1 BeautifulSoup介绍
1、BeautifulSoup作用
1、BeautifulSoup是一个模块,该模块用于接收一个HTML或XML字符串,然后将其进行格式化
2、之后遍可以使用他提供的方法进行快速查找指定元素,从而使得在HTML或XML中查找指定元素变得简单
2、安装
pip3 install beautifulsoup4
pip install lxml #lxml是一个比beautifulsoup4更强大的库(居然直接用pip就安装成功了)
3、lxml与html.parser比较
1. 两者都是把文本转成对象的方法,lxml是第三方库,但是性能好(生产用这个),html.parser 是python内置模块无需安装
2. soup = BeautifulSoup(response.text,features='lxml') #lxml是第三方库,但是性能好(生产用这个)
3. soup = BeautifulSoup(response.text,features='html.parser') # html.parser 是python内置模块无需安装
4、lxml结合BeautifulSoup举例
from bs4 import BeautifulSoup html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a</a>
<a class="c1" id="link2" name="ha">i am a</a>
</body>
</html>
"""
soup = BeautifulSoup(html_doc, features="lxml")
#1、找到第一个a标签
tag1 = soup.find(name='a')
#2、找到所有的a标签
tag2 = soup.find_all(name='a')
#3、找到id=link2的标签
tag3 = soup.select('#link2') print(tag1) # <a class="c1" id="i1" name="ha">i am a</a>
print(tag2) # [<a class="c1" id="i1" name="ha">i am a</a>, <a class="c1" id="link2" name="ha">i am a</a>]
print(tag3) # [<a class="c1" id="link2" name="ha">i am a</a>]
lxml结合BeautifulSoup举例
1.2 BeautifulSoup常用方法
1、name,标签名称(tag.name)
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a</a>
<a class="c1" id="link2" name="ha">i am a</a>
</body>
</html>
""" from bs4 import BeautifulSoup soup = BeautifulSoup(html_doc, features="lxml")
tag = soup.find('a') # 找到第一个a标签
print(tag.name) # 获取标签名称(如果是a标签,name=a)
tag.name = 'span' # 将获取的a标签变成span标签 print(soup) # <html><head><title>The Dormouse's story</title></head>
# <body>
# <span class="c1" id="i1" name="ha">i am a</span>
# <a class="c1" id="link2" name="ha">i am a</a>
# </body>
# </html>
name,标签名称
2、attr,标签属性(tag.attrs)
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a</a>
<a class="c1" id="link2" name="ha">i am a</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('a')
attrs = tag.attrs # 获取所有属性
print(attrs) # 格式:{'name': 'ha', 'class': ['c1'], 'id': 'i1'}
tag.attrs = {'ik':123} # 将属性替换成 ik="123"
tag.attrs['id'] = 'iiiii' # 在原来的基础上添加一个 id="iiiii"属性
print(soup) # <a id="iiiii" ik="123">
attr,标签属性
3、children,所有子标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a</a>
<a class="c1" id="link2" name="ha">i am a</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body')
v = body.children #找到所有孩子标签 for tag in v:
print(tag)
# <a class="c1" id="i1" name="ha">i am a</a>
# <a class="c1" id="link2" name="ha">i am a</a>
children,所有子标签
4、descendants,所有子子孙孙标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body')
v = body.descendants #找到所有子子孙孙标签 for tag in v:
print(tag)
# <a class="c1" id="i1" name="ha">i am a1</a>
# i am a1
# <a class="c1" id="link2" name="ha">i am a2</a>
# i am a2
descendants,所有子子孙孙标签
5、clear,将标签的所有子标签全部清空(保留标签名)
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('body')
tag.clear() # 结果仅保留了body这个标签名,其他全部删除了 print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body></body>
# </html>
clear,将标签的所有子标签全部清空(保留标签名)
6、decompose,递归的删除所有的标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body')
body.decompose() # 结果将body标签都删除了,不保留body这个标签名 print(soup)
# <html><head><title>The Dormouse's story</title></head>
# </html>
decompose,递归的删除所有的标签
7、extract,递归的删除所有的标签,并获取删除的标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body')
v = body.extract() print(v) # v就是删除的body标签的内容
# <body>
# <a class="c1" id="i1" name="ha">i am a1</a>
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body> print(soup) # soup是将body标签删除后的内容,还保留body这个空标签
# <html><head><title>The Dormouse's story</title></head>
# </html>
extract,递归的删除所有的标签,并获取删除的标签
8、find,获取匹配的第一个标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('a')
print(tag) # <a class="c1" id="i1" name="ha">i am a1</a> # recursive=False那么只会到儿子里去查找,不会到子子孙孙查找
# text='Lacie' 文本必须是这样的
tag1 = soup.find(name='a', attrs={'class': 'sister'}, recursive=True, text='Lacie')
tag2 = soup.find(name='a', class_='sister', recursive=True, text='Lacie')
print(tag1) # None
print(tag2) # None
find,获取匹配的第一个标签
9、find_all,获取匹配的所有标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") #1、找到所有a标签
tags = soup.find_all('a')
print(tags) # [<a class="c1" id="i1" name="ha">i am a1</a>, <a class="c1" id="link2" name="ha">i am a2</a>] #2、limit=1限制只找一个
tags = soup.find_all('a',limit=1) # limit限制只找多少个
print(tags) # [<a class="c1" id="i1" name="ha">i am a1</a>] #3、找到所有的a标签和div标签
v = soup.find_all(name=['a','div'])
print(v) # [<a class="c1" id="i1" name="ha">i am a1</a>, <a class="c1" id="link2" name="ha">i am a2</a>] #4、找到所欲class名为:'sister0', 'sister'
v = soup.find_all(class_=['sister0', 'sister'])
print(v) # [] #5、找到所有id='link1'或id='link2'的标签
# v = soup.find_all(href=['link1','link2']) # 同理
v = soup.find_all(id=['link1','link2'])
print(v) # [<a class="c1" id="link2" name="ha">i am a2</a>] # ####### 正则 #######
import re
rep = re.compile('p')
rep = re.compile('^p') #找到所有以p开头的标签
v = soup.find_all(name=rep) rep = re.compile('sister.*')
v = soup.find_all(class_=rep)
print(v) rep = re.compile('http://www.oldboy.com/static/.*')
v = soup.find_all(href=rep)
print(v) # ####### 方法筛选 #######
def func(tag):
return tag.has_attr('class') and tag.has_attr('id')
v = soup.find_all(name=func)
print(v) # get,获取标签属性
tag = soup.find('a')
v = tag.get('id')
print(v)
find_all,获取匹配的所有标签
10、decode,转换为字符串(含当前标签);decode_contents(不含当前标签)
作用:将body这个对象转换成字符串类型
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body') #1、包含body这个标签
v1 = body.decode() #v1包含body这个标签
print(v1)
# <body>
# <a class="c1" id="i1" name="ha">i am a1</a>
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body> #2、不包含body这个标签
v2 = body.decode_contents() #v2不包含body这个标签
print(v2)
# <a class="c1" id="i1" name="ha">i am a1</a>
# <a class="c1" id="link2" name="ha">i am a2</a>
decode,转换为字符串(含当前标签);decode_contents(不含当前标签)
11、encode,转换为字节(含当前标签);encode_contents(不含当前标签)
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") body = soup.find('body') #1、包含body这个标签
v1 = body.encode() #v1包含body这个标签(字节格式)
print(v1)
# b'<body>\n<a class="c1" id="i1" name="ha">i am a1</a>\n<a class="c1" id="link2" name="ha">i am a2</a>\n</body>' #2、不包含body这个标签
v2 = body.encode_contents() #v2不包含body这个标签(字节格式)
print(v2)
# b'\n<a class="c1" id="i1" name="ha">i am a1</a>\n<a class="c1" id="link2" name="ha">i am a2</a>\n'
encode,转换为字节(含当前标签);encode_contents(不含当前标签)
12、has_attr,检查标签是否具有该属性
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('a')
v = tag.has_attr('id')
print(v) # True
has_attr,检查标签是否具有该属性
13、get_text,获取标签内部文本内容
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('a')
v = tag.get_text('id')
print(v) # i am a1
get_text,获取标签内部文本内容
14、index,检查标签在某标签中的索引位置
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('body')
v = tag.index(tag.find('a'))
print(v) #
index,检查标签在某标签中的索引位置
15、is_empty_element,是否是空标签(是否可以是空)或者自闭合标签
作用:判断是否是如下标签:'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('a')
print(tag) # <a class="c1" id="i1" name="ha">i am a1</a
v = tag.is_empty_element
print(v) # False
is_empty_element,是否是空标签(是否可以是空)或者自闭合标签
16、append在当前标签内部追加一个标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") tag = soup.find('body') #1、找到指定第一个a标签追加到最后
tag.append(soup.find('a'))
print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# <a class="c1" id="link2" name="ha">i am a2</a>
# <a class="c1" id="i1" name="ha">i am a1</a></body>
# </html> #2、创建一个a标签追加到末尾
from bs4.element import Tag
obj = Tag(name='i',attrs={'id': 'it'}) #创建一个i标签,并设置属性
obj.string = '我是一个新来的' #给他这个创建的i标签添加内容
tag = soup.find('body')
tag.append(obj) #将创建的a标签添加到body中 print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# <a class="c1" id="link2" name="ha">i am a2</a>
# <a class="c1" id="i1" name="ha">i am a1</a><i id="it">我是一个新来的</i></body>
# </html>
append在当前标签内部追加一个标签
17、insert在当前标签内部指定位置插入一个标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") #1、创建一个新标签插入到第二号位置
from bs4.element import Tag
obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('body')
tag.insert(2, obj) print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# <a class="c1" id="i1" name="ha">i am a1</a>
# <i id="it">我是一个新来的</i>
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body>
# </html>
insert在当前标签内部指定位置插入一个标签
18、insert_after,insert_before 在当前标签后面或前面插入
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") from bs4.element import Tag
obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的' tag = soup.find('a')
# tag.insert_before(obj) #1、创建一个i标签,追加到找到的第一个a标签的后面
tag.insert_after(obj)
print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# <a class="c1" id="i1" name="ha">i am a1</a>
# <i id="it">我是一个新来的</i>
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body>
# </html>
insert_after,insert_before 在当前标签后面或前面插入
19、replace_with 将当前标签替换为指定标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") #1、使用新创建的i标签替换找到的第一个a标签
from bs4.element import Tag
obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('a')
tag.replace_with(obj) #用我们创建的i标签替换找到的div标签
print(soup)
replace_with 在当前标签替换为指定标签
20、wrap,将指定标签把当前标签包裹起来
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") from bs4.element import Tag
obj1 = Tag(name='div', attrs={'id': 'it'})
obj1.string = '我是一个新来的' #1、创建一个div标签包裹住找到的第一个a标签
tag = soup.find('a')
v = tag.wrap(obj1) #用创建的div标签包裹找到的a标签
print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# <div id="it">我是一个新来的<a class="c1" id="i1" name="ha">i am a1</a></div>
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body>
# </html>
wrap,将指定标签把当前标签包裹起来
21、unwrap,去掉当前标签,将保留其包裹的标签
html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<a class="c1" id="i1" name="ha">i am a1</a>
<a class="c1" id="link2" name="ha">i am a2</a>
</body>
</html>
""" from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, features="lxml") #1、找到第一个a标签,并去除包裹的标签,所以就只剩下内容了
tag = soup.find('a')
v = tag.unwrap() print(soup)
# <html><head><title>The Dormouse's story</title></head>
# <body>
# i am a1
# <a class="c1" id="link2" name="ha">i am a2</a>
# </body>
# </html>
unwrap,去掉当前标签,将保留其包裹的标签
22、查找某标签的关联标签
tag.find_next(...)
tag.find_all_next(...)
tag.find_next_sibling(...)
tag.find_next_siblings(...) tag.find_previous(...)
tag.find_all_previous(...)
tag.find_previous_sibling(...)
tag.find_previous_siblings(...) tag.find_parent(...)
tag.find_parents(...) # 参数同find_all
查找某标签的关联标签
23、select,select_one, CSS选择器
soup.select("title") #找到title标签
soup.select("p nth-of-type(3)")
soup.select("body a") #找到html head 中的title标签
soup.select("html head title") tag = soup.select("span,a") soup.select("head > title")
soup.select("p > a")
soup.select("p > a:nth-of-type(2)")
soup.select("p > #link1")
soup.select("body > a")
soup.select("#link1 ~ .sister")
soup.select("#link1 + .sister")
soup.select(".sister")
soup.select("[class~=sister]")
soup.select("#link1")
soup.select("a#link2")
soup.select('a[href]')
soup.select('a[href="http://example.com/elsie"]')
soup.select('a[href^="http://example.com/"]')
soup.select('a[href$="tillie"]')
soup.select('a[href*=".com/el"]') from bs4.element import Tag def default_candidate_generator(tag):
for child in tag.descendants:
if not isinstance(child, Tag):
continue
if not child.has_attr('href'):
continue
yield child
tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator) def default_candidate_generator(tag):
for child in tag.descendants:
if not isinstance(child, Tag):
continue
if not child.has_attr('href'):
continue
yield child
tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1)
print(type(tags), tags)
select,select_one, CSS选择器
24、标签的内容(不仅可以读还修改)
tag = soup.find('span') #
print(tag.string) # 获取span标签中的内容
tag.string = 'new content' # 将span标签中的内容改成'new content'
print(soup) tag = soup.find('body')
print(tag.string)
tag.string = 'xxx'
print(soup) tag = soup.find('body')
v = tag.stripped_strings # 递归内部获取所有标签的文本
print(v)
标签的内容(不仅可以读还修改)
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