<p>您可以使用<code>reverse=True</code>将自定义<code>key</code>传递给<code>sorted</code>函数以获得降序:</p>
<pre><code>>>> res = [{'cpunumber': '40.0', 'servername': 'f02wn01', 'cpucore_sum': '5.0', 'cpucore_00': '0.399414', 'datetime': '1438887255'},
... {'cpunumber': '40.0', 'servername': 'f02wn01', 'cpucore_sum': '9.375', 'cpucore_00': '1.597656', 'datetime': '1438887250'},
... {'cpunumber': '40.0', 'servername': 'f02wn01', 'cpucore_sum': '3.195312', 'cpucore_00': '0.0', 'datetime': '1438887240'},
... {'cpunumber': '40.0', 'servername': 'f02wn01', 'cpucore_sum': '5.59375', 'cpucore_00': '1.0', 'datetime': '1438887245'}]
>>> sorted(res, key=lambda x: x["datetime"], reverse=True)
[{'cpucore_00': '0.399414',
'cpucore_sum': '5.0',
'cpunumber': '40.0',
'datetime': '1438887255',
'servername': 'f02wn01'},
{'cpucore_00': '1.597656',
'cpucore_sum': '9.375',
'cpunumber': '40.0',
'datetime': '1438887250',
'servername': 'f02wn01'},
{'cpucore_00': '1.0',
'cpucore_sum': '5.59375',
'cpunumber': '40.0',
'datetime': '1438887245',
'servername': 'f02wn01'},
{'cpucore_00': '0.0',
'cpucore_sum': '3.195312',
'cpunumber': '40.0',
'datetime': '1438887240',
'servername': 'f02wn01'}]
</code></pre>
<p>您还可以使用列表的<code>.sort</code>方法对其进行就地排序(使用<code>reverse=True</code>表示降序):</p>
<pre><code>>>> res.sort(key=lambda x: x["datetime"])
>>> res
[{'cpucore_sum': '3.195312', 'cpucore_00': '0.0', 'servername': 'f02wn01', 'cpunumber': '40.0', 'datetime': '1438887240'}, {'cpucore_sum': '5.59375', 'cpucore_00': '1.0', 'servername': 'f02wn01', 'cpunumber': '40.0', 'datetime': '1438887245'}, {'cpucore_sum': '9.375', 'cpucore_00': '1.597656', 'servername': 'f02wn01', 'cpunumber': '40.0', 'datetime': '1438887250'}, {'cpucore_sum': '5.0', 'cpucore_00': '0.399414', 'servername': 'f02wn01', 'cpunumber': '40.0', 'datetime': '1438887255'}]
</code></pre>
<p>如果您的所有<code>dict</code>都不能保证有<code>"datetime"</code>键,您可以使用<code>x.get("datetime")</code>而不是<code>x["datetime"]</code>。你知道吗</p>