Python扭曲的JSON解碼

Question

我已經使用python扭曲庫開發了以下代碼：

class Cache(protocol.Protocol):
    def __init__(self, factory):
        self.factory = factory

    def dataReceived(self, data):
        request = json.loads(data)
        self.factory.handle[request['command']](**request)
        self.transport.write(data)

class CacheFactory(protocol.Factory):
    def buildProtocol(self, addr):
        return Cache(self)
    def handle_get(self, **kwargs):
        print 'get\n', kwargs
    def handle_set(self, **kwargs):
        print 'set\n', kwargs
    def handle_delete(self, **kwargs):
        print 'delete\n', kwargs
    handle = {
        'get': handle_get,
        'set': handle_set,
        'delete': handle_delete,
    }

reactor.listenTCP(int(sys.argv[1]), CacheFactory())
reactor.run()

我使用telnet運行客戶端連接：

Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
{"command": "set", "value": 1234567890}
Connection closed by foreign host.

引發異常：

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 84, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/log.py", line 69, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/selectreactor.py", line 146, in _doReadOrWrite
    why = getattr(selectable, method)()
  File "/usr/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 460, in doRead
    rval = self.protocol.dataReceived(data)
  File "./server.py", line 18, in dataReceived
    self.factory.handle[request['command']](**request)
exceptions.TypeError: handle_set() takes exactly 1 argument (0 given)

我不明白。 self.factory.handle[request['command']](**request)行可能有問題，但我認為這是正確的-它隱式地傳遞了self參數（畢竟是方法）並顯式地解壓縮了請求參數。 異常消息說該函數接受1個參數，這是一個謊言:)，因為它接受2個參數： self, **kwargs 。 而且我傳遞了2個參數也不是正確的，因為我傳遞了2個參數。

有人可以幫助我發現問題嗎？

---

如果有幫助，則將json請求解碼為：

{u'command': u'set', u'value': 1234567890}

Answer 1

到目前為止， handle_*方法是實例方法，而handle字典指向未綁定的方法。 也就是說， self不會被隱式傳遞。 嘗試以下方法：

class CacheFactory(protocol.Factory):
    def buildProtocol(self, addr):
        return Cache(self)
    def handle_get(self, **kwargs):
        print 'get\n', kwargs
    def handle_set(self, **kwargs):
        print 'set\n', kwargs
    def handle_delete(self, **kwargs):
        print 'delete\n', kwargs
    def __init__(self, *args, **kwargs):
        protocol.Factory.__init__(self, *args, **kwargs)
        self.handle = {
            'get': self.handle_get,
            'set': self.handle_set,
            'delete': self.handle_delete,
        }

另外，您可以保持handle不變並執行以下操作：

    def dataReceived(self, data):
        request = json.loads(data)
        self.factory.handle[request['command']](self.factory, **request)
        self.transport.write(data)

或者，你可以采取這種做法，那么你並不需要一個handle字典兩種方式：

    def dataReceived(self, data):
        request = json.loads(data)
        getattr(self.factory, "handle_%s" % (request['command'],))(**request)
        self.transport.write(data)

還要注意，由於數據包可能會被任意拆分，因此dataReceived （現在）是不安全的，也就是說，您可能不會一槍就收到整個json消息。