先来大致看看HTMLParser的源代码吧：
|
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"""A parser for HTML and XHTML."""
# This file is based on sgmllib.py, but the API is slightly different.
# XXX There should be a way to distinguish between PCDATA (parsed
# character data -- the normal case), RCDATA (replaceable character
# data -- only char and entity references and end tags are special)
# and CDATA (character data -- only end tags are special).
import
markupbase
import
re
# Regular expressions used for parsing
interesting_normal
=
re.
compile
(
'[&<]'
)
interesting_cdata
=
re.
compile
(r
'<(/|\Z)'
)
incomplete
=
re.
compile
(
'&[a-zA-Z#]'
)
entityref
=
re.
compile
(
'&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]'
)
charref
=
re.
compile
(
'&#(?:[0-9]+|[xX][0-9a-fA-F]+)[^0-9a-fA-F]'
)
starttagopen
=
re.
compile
(
'<[a-zA-Z]'
)
piclose
=
re.
compile
(
'>'
)
commentclose
=
re.
compile
(r
'--\s*>'
)
tagfind
=
re.
compile
(
'[a-zA-Z][-.a-zA-Z0-9:_]*'
)
attrfind
=
re.
compile
(
r
'\s*([a-zA-Z_][-.:a-zA-Z_0-9]*)(\s*=\s*'
r
'(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~@]*))?'
)
locatestarttagend
=
re.
compile
(r
"""
<[a-zA-Z][-.a-zA-Z0-9:_]* # tag name
(?:\s+ # whitespace before attribute name
(?:[a-zA-Z_][-.:a-zA-Z0-9_]* # attribute name
(?:\s*=\s* # value indicator
(?:'[^']*' # LITA-enclosed value
|\"[^\"]*\" # LIT-enclosed value
|[^'\">\s]+ # bare value
)
)?
)
)*
\s* # trailing whitespace
"""
, re.VERBOSE)
endendtag
=
re.
compile
(
'>'
)
endtagfind
=
re.
compile
(
'</\s*([a-zA-Z][-.a-zA-Z0-9:_]*)\s*>'
)
class
HTMLParseError(Exception):
"""Exception raised for all parse errors."""
def
__init__(
self
, msg, position
=
(
None
,
None
)):
assert
msg
self
.msg
=
msg
self
.lineno
=
position[
0
]
self
.offset
=
position[
1
]
def
__str__(
self
):
result
=
self
.msg
if
self
.lineno
is
not
None
:
result
=
result
+
", at line %d"
%
self
.lineno
if
self
.offset
is
not
None
:
result
=
result
+
", column %d"
%
(
self
.offset
+
1
)
return
result
class
HTMLParser(markupbase.ParserBase):
"""Find tags and other markup and call handler functions.
Usage:
p = HTMLParser()
p.feed(data)
...
p.close()
Start tags are handled by calling self.handle_starttag() or
self.handle_startendtag(); end tags by self.handle_endtag(). The
data between tags is passed from the parser to the derived class
by calling self.handle_data() with the data as argument (the data
may be split up in arbitrary chunks). Entity references are
passed by calling self.handle_entityref() with the entity
reference as the argument. Numeric character references are
passed to self.handle_charref() with the string containing the
reference as the argument.
"""
CDATA_CONTENT_ELEMENTS
=
(
"script"
,
"style"
)
def
__init__(
self
):
"""Initialize and reset this instance."""
self
.reset()
def
reset(
self
):
"""Reset this instance. Loses all unprocessed data."""
self
.rawdata
=
''
self
.lasttag
=
'???'
self
.interesting
=
interesting_normal
markupbase.ParserBase.reset(
self
)
def
feed(
self
, data):
"""Feed data to the parser.
Call this as often as you want, with as little or as much text
as you want (may include '\n').
"""
self
.rawdata
=
self
.rawdata
+
data
self
.goahead(
0
)
def
close(
self
):
"""Handle any buffered data."""
self
.goahead(
1
)
def
error(
self
, message):
raise
HTMLParseError(message,
self
.getpos())
__starttag_text
=
None
def
get_starttag_text(
self
):
"""Return full source of start tag: '<...>'."""
return
self
.__starttag_text
def
set_cdata_mode(
self
):
self
.interesting
=
interesting_cdata
def
clear_cdata_mode(
self
):
self
.interesting
=
interesting_normal
# Internal -- handle data as far as reasonable. May leave state
# and data to be processed by a subsequent call. If 'end' is
# true, force handling all data as if followed by EOF marker.
def
goahead(
self
, end):
rawdata
=
self
.rawdata
i
=
0
n
=
len
(rawdata)
while
i < n:
match
=
self
.interesting.search(rawdata, i)
# < or &
if
match:
j
=
match.start()
else
:
j
=
n
if
i < j:
self
.handle_data(rawdata[i:j])
i
=
self
.updatepos(i, j)
if
i
=
=
n:
break
startswith
=
rawdata.startswith
if
startswith(
'<'
, i):
if
starttagopen.match(rawdata, i):
# < + letter
k
=
self
.parse_starttag(i)
elif
startswith(
"</"
, i):
k
=
self
.parse_endtag(i)
elif
startswith(
"<!--"
, i):
k
=
self
.parse_comment(i)
elif
startswith(
"<?"
, i):
k
=
self
.parse_pi(i)
elif
startswith(
"<!"
, i):
k
=
self
.parse_declaration(i)
elif
(i
+
1
) < n:
self
.handle_data(
"<"
)
k
=
i
+
1
else
:
break
if
k <
0
:
if
end:
self
.error(
"EOF in middle of construct"
)
break
i
=
self
.updatepos(i, k)
elif
startswith(
"&#"
, i):
match
=
charref.match(rawdata, i)
if
match:
name
=
match.group()[
2
:
-
1
]
self
.handle_charref(name)
k
=
match.end()
if
not
startswith(
';'
, k
-
1
):
k
=
k
-
1
i
=
self
.updatepos(i, k)
continue
else
:
if
";"
in
rawdata[i:]:
#bail by consuming &#
self
.handle_data(rawdata[
0
:
2
])
i
=
self
.updatepos(i,
2
)
break
elif
startswith(
'&'
, i):
match
=
entityref.match(rawdata, i)
if
match:
name
=
match.group(
1
)
self
.handle_entityref(name)
k
=
match.end()
if
not
startswith(
';'
, k
-
1
):
k
=
k
-
1
i
=
self
.updatepos(i, k)
continue
match
=
incomplete.match(rawdata, i)
if
match:
# match.group() will contain at least 2 chars
if
end
and
match.group()
=
=
rawdata[i:]:
self
.error(
"EOF in middle of entity or char ref"
)
# incomplete
break
elif
(i
+
1
) < n:
# not the end of the buffer, and can't be confused
# with some other construct
self
.handle_data(
"&"
)
i
=
self
.updatepos(i, i
+
1
)
else
:
break
else
:
assert
0
,
"interesting.search() lied"
# end while
if
end
and
i < n:
self
.handle_data(rawdata[i:n])
i
=
self
.updatepos(i, n)
self
.rawdata
=
rawdata[i:]
# Internal -- parse processing instr, return end or -1 if not terminated
def
parse_pi(
self
, i):
rawdata
=
self
.rawdata
assert
rawdata[i:i
+
2
]
=
=
'<?'
,
'unexpected call to parse_pi()'
match
=
piclose.search(rawdata, i
+
2
)
# >
if
not
match:
return
-
1
j
=
match.start()
self
.handle_pi(rawdata[i
+
2
: j])
j
=
match.end()
return
j
# Internal -- handle starttag, return end or -1 if not terminated
def
parse_starttag(
self
, i):
self
.__starttag_text
=
None
endpos
=
self
.check_for_whole_start_tag(i)
if
endpos <
0
:
return
endpos
rawdata
=
self
.rawdata
self
.__starttag_text
=
rawdata[i:endpos]
# Now parse the data between i+1 and j into a tag and attrs
attrs
=
[]
match
=
tagfind.match(rawdata, i
+
1
)
assert
match,
'unexpected call to parse_starttag()'
k
=
match.end()
self
.lasttag
=
tag
=
rawdata[i
+
1
:k].lower()
while
k < endpos:
m
=
attrfind.match(rawdata, k)
if
not
m:
break
attrname, rest, attrvalue
=
m.group(
1
,
2
,
3
)
if
not
rest:
attrvalue
=
None
elif
attrvalue[:
1
]
=
=
'\''
=
=
attrvalue[
-
1
:]
or
\
attrvalue[:
1
]
=
=
'"'
=
=
attrvalue[
-
1
:]:
attrvalue
=
attrvalue[
1
:
-
1
]
attrvalue
=
self
.unescape(attrvalue)
attrs.append((attrname.lower(), attrvalue))
k
=
m.end()
end
=
rawdata[k:endpos].strip()
if
end
not
in
(
">"
,
"/>"
):
lineno, offset
=
self
.getpos()
if
"\n"
in
self
.__starttag_text:
lineno
=
lineno
+
self
.__starttag_text.count(
"\n"
)
offset
=
len
(
self
.__starttag_text) \
-
self
.__starttag_text.rfind(
"\n"
)
else
:
offset
=
offset
+
len
(
self
.__starttag_text)
self
.error(
"junk characters in start tag: %r"
%
(rawdata[k:endpos][:
20
],))
if
end.endswith(
'/>'
):
# XHTML-style empty tag: <span attr="value" />
self
.handle_startendtag(tag, attrs)
else
:
self
.handle_starttag(tag, attrs)
if
tag
in
self
.CDATA_CONTENT_ELEMENTS:
self
.set_cdata_mode()
return
endpos
# Internal -- check to see if we have a complete starttag; return end
# or -1 if incomplete.
def
check_for_whole_start_tag(
self
, i):
rawdata
=
self
.rawdata
m
=
locatestarttagend.match(rawdata, i)
if
m:
j
=
m.end()
next
=
rawdata[j:j
+
1
]
if
next
=
=
">"
:
return
j
+
1
if
next
=
=
"/"
:
if
rawdata.startswith(
"/>"
, j):
return
j
+
2
if
rawdata.startswith(
"/"
, j):
# buffer boundary
return
-
1
# else bogus input
self
.updatepos(i, j
+
1
)
self
.error(
"malformed empty start tag"
)
if
next
=
=
"":
# end of input
return
-
1
if
next
in
(
"abcdefghijklmnopqrstuvwxyz=/"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
):
# end of input in or before attribute value, or we have the
# '/' from a '/>' ending
return
-
1
self
.updatepos(i, j)
self
.error(
"malformed start tag"
)
raise
AssertionError(
"we should not get here!"
)
# Internal -- parse endtag, return end or -1 if incomplete
def
parse_endtag(
self
, i):
rawdata
=
self
.rawdata
assert
rawdata[i:i
+
2
]
=
=
"</"
,
"unexpected call to parse_endtag"
match
=
endendtag.search(rawdata, i
+
1
)
# >
if
not
match:
return
-
1
j
=
match.end()
match
=
endtagfind.match(rawdata, i)
# </ + tag + >
if
not
match:
self
.error(
"bad end tag: %r"
%
(rawdata[i:j],))
tag
=
match.group(
1
)
self
.handle_endtag(tag.lower())
self
.clear_cdata_mode()
return
j
# Overridable -- finish processing of start+end tag: <tag.../>
def
handle_startendtag(
self
, tag, attrs):
self
.handle_starttag(tag, attrs)
self
.handle_endtag(tag)
# Overridable -- handle start tag
def
handle_starttag(
self
, tag, attrs):
pass
# Overridable -- handle end tag
def
handle_endtag(
self
, tag):
pass
# Overridable -- handle character reference
def
handle_charref(
self
, name):
pass
# Overridable -- handle entity reference
def
handle_entityref(
self
, name):
pass
# Overridable -- handle data
def
handle_data(
self
, data):
pass
# Overridable -- handle comment
def
handle_comment(
self
, data):
pass
# Overridable -- handle declaration
def
handle_decl(
self
, decl):
pass
# Overridable -- handle processing instruction
def
handle_pi(
self
, data):
pass
def
unknown_decl(
self
, data):
self
.error(
"unknown declaration: %r"
%
(data,))
# Internal -- helper to remove special character quoting
entitydefs
=
None
def
unescape(
self
, s):
if
'&'
not
in
s:
return
s
def
replaceEntities(s):
s
=
s.groups()[
0
]
if
s[
0
]
=
=
"#"
:
s
=
s[
1
:]
if
s[
0
]
in
[
'x'
,
'X'
]:
c
=
int
(s[
1
:],
16
)
else
:
c
=
int
(s)
return
unichr
(c)
else
:
# Cannot use name2codepoint directly, because HTMLParser supports apos,
# which is not part of HTML 4
import
htmlentitydefs
if
HTMLParser.entitydefs
is
None
:
entitydefs
=
HTMLParser.entitydefs
=
{
'apos'
:u
"'"
}
for
k, v
in
htmlentitydefs.name2codepoint.iteritems():
entitydefs[k]
=
unichr
(v)
try
:
return
self
.entitydefs[s]
except
KeyError:
return
'&'
+
s
+
';'
return
re.sub(r
"&(#?[xX]?(?:[0-9a-fA-F]+|\w{1,8}));"
, replaceEntities, s)
|
大家可以看到，其实内部的很多的方法都是没有实现的，所以需要我们继承这个类，自己去实现一些方法。关于HTMLParser的方法，大家可以参考官方文档：
http://docs.python.org/library/htmlparser.html#HTMLParser.HTMLParser （英文，笔者没有多少时间去翻译这些）
另外，给一个例子大家对照着看看，我相信这么简单的例子，大家都能看懂的。
假设我们要处理的文件在d盘根目录下，名字为hello.html,文件的内容为：
<!
DOCTYPE
html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<
head
>
<
meta
http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<
title
>Rollen Holt - cnblogs</
title
>
<
meta
name="keywords" content="Rollen Holt,rollenholt" />
<
link
id="MainCss" type="text/css" rel="stylesheet" href="http://www.cnblogs.com/Skins/kubrick/style.css"/>
<
link
title="RSS" type="application/rss+xml" rel="alternate" href="http://www.cnblogs.com/rollenholt/rss"/>
<
link
title="RSD" type="application/rsd+xml" rel="EditURI" href="http://www.cnblogs.com/rollenholt/rsd.xml"/>
<
link
type="application/wlwmanifest+xml" rel="wlwmanifest" href="http://www.cnblogs.com/rollenholt/wlwmanifest.xml"/>
<
script
src="/script/common.js" type="text/javascript"></
script
>
<
script
src="http://common.cnblogs.com/script/jquery.json-2.2.min.js" type="text/javascript"></
script
>
</
head
>
<
body
>
<
a
name="top"></
a
>
<
form
method="post" action="" id="Form1">
<
div
class="aspNetHidden">
<
input
type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="" />
</
div
>
</
form
>
</
body
>
</
html
>
|
我们的python代码为：
#coding=utf-8
from
HTMLParser
import
HTMLParser
class
MyParser(HTMLParser):
"""一个简单的HTMLparser的例子"""
def
handle_decl(
self
, decl):
"""处理头文档"""
HTMLParser.handle_decl(
self
, decl)
print
decl
def
handle_starttag(
self
, tag, attrs):
"""处理起始标签"""
HTMLParser.handle_starttag(
self
, tag, attrs)
if
not
HTMLParser.get_starttag_text(
self
).endswith(
"/>"
):
print
"<"
,tag,
">"
def
handle_data(
self
, data):
"""处理文本元素"""
HTMLParser.handle_data(
self
, data)
print
data,
def
handle_endtag(
self
, tag):
"""处理结束标签"""
HTMLParser.handle_endtag(
self
, tag)
if
not
HTMLParser.get_starttag_text(
self
).endswith(
"/>"
):
print
"</"
,tag,
">"
def
handle_startendtag(
self
, tag, attrs):
"""处理自闭标签"""
HTMLParser.handle_startendtag(
self
, tag, attrs)
print
HTMLParser.get_starttag_text(
self
)
def
handle_comment(
self
, data):
"""处理注释"""
HTMLParser.handle_comment(
self
, data)
print
data
def
close(
self
):
HTMLParser.close(
self
)
print
"parser over"
demo
=
MyParser()
demo.feed(
open
(
"d:\\hello.html"
).read())
demo.close()
|
输出的结果为：
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
< html >
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parser over
