3.3.5 使用HtmlDiff对象
当想创建一个HTML来表示文件之间差异时，就可以使用HtmlDiff对象。特别对于Web服务器的应用就更加方便了，直接把数据返回即可。
例子：
#python3.4.3
import difflib
text1 = ''' 1. Beautiful is better than ugly.
2. Explicit is better than implicit.
3. Simple is better than complex.
4. Complex is better than complicated.
'''.splitlines(keepends=True)
text2 = ''' 1. Beautiful is better than ugly.
3. Simple is better than complex.
4. Complicated is better than complex.
5. Flat is better than nested.
'''.splitlines(keepends=True)
diff = difflib.HtmlDiff().make_file(text1, text2)
print(diff)
结果输出如下：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type"
content="text/html; charset=ISO-8859-1" />
<title></title>
<style type="text/css">
table.diff {font-family:Courier; border:medium;}
.diff_header {background-color:#e0e0e0}
td.diff_header {text-align:right}
.diff_next {background-color:#c0c0c0}
.diff_add {background-color:#aaffaa}
.diff_chg {background-color:#ffff77}
.diff_sub {background-color:#ffaaaa}
</style>
</head>
<body>
<table class="diff" id="difflib_chg_to0__top"
cellspacing="0" cellpadding="0" rules="groups" >
<colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
<colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
<tbody>
<tr><td class="diff_next" id="difflib_chg_to0__0"><a href="#difflib_chg_to0__0">f</a></td><td class="diff_header" id="from0_1">1</td><td nowrap="nowrap"> 1. Beautiful is better than ugly.</td><td class="diff_next"><a href="#difflib_chg_to0__0">f</a></td><td class="diff_header" id="to0_1">1</td><td nowrap="nowrap"> 1. Beautiful is better than ugly.</td></tr>
<tr><td class="diff_next"><a href="#difflib_chg_to0__top">t</a></td><td class="diff_header" id="from0_2">2</td><td nowrap="nowrap"><span class="diff_sub"> 2. Explicit is better than implicit.</span></td><td class="diff_next"><a href="#difflib_chg_to0__top">t</a></td><td class="diff_header"></td><td nowrap="nowrap"></td></tr>
<tr><td class="diff_next"></td><td class="diff_header" id="from0_3">3</td><td nowrap="nowrap"> 3. Simple is better than complex.</td><td class="diff_next"></td><td class="diff_header" id="to0_2">2</td><td nowrap="nowrap"> 3.<span class="diff_add"> </span> Simple is better than complex.</td></tr>
<tr><td class="diff_next"></td><td class="diff_header" id="from0_4">4</td><td nowrap="nowrap"><span class="diff_sub"> 4. Complex is better than complicated.</span></td><td class="diff_next"></td><td class="diff_header" id="to0_3">3</td><td nowrap="nowrap"><span class="diff_add"> 4. Complicated is better than complex.</span></td></tr>
<tr><td class="diff_next"></td><td class="diff_header"></td><td nowrap="nowrap"></td><td class="diff_next"></td><td class="diff_header" id="to0_4">4</td><td nowrap="nowrap"><span class="diff_add"> 5. Flat is better than nested.</span></td></tr>
<tr><td class="diff_next"></td><td class="diff_header" id="from0_5">5</td><td nowrap="nowrap"> </td><td class="diff_next"></td><td class="diff_header" id="to0_5">5</td><td nowrap="nowrap"> </td></tr>
</tbody>
</table>
<table class="diff" summary="Legends">
<tr> <th colspan="2"> Legends </th> </tr>
<tr> <td> <table border="" summary="Colors">
<tr><th> Colors </th> </tr>
<tr><td class="diff_add"> Added </td></tr>
<tr><td class="diff_chg">Changed</td> </tr>
<tr><td class="diff_sub">Deleted</td> </tr>
</table></td>
<td> <table border="" summary="Links">
<tr><th colspan="2"> Links </th> </tr>
<tr><td>(f)irst change</td> </tr>
<tr><td>(n)ext change</td> </tr>
<tr><td>(t)op</td> </tr>
</table></td> </tr>
</table>
</body>
</html>
把这段HTML文本写到一个文件里，使用浏览器打开会显示如下：
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