写出一个cache对websocket缓存的代码，要求有心跳机制和重连机制

以下是一个简单的cache对websocket缓存的代码，包括心跳机制和重连机制：

import websocket
import time

class WebSocketCache:
    def __init__(self, url):
        self.url = url
        self.ws = None
        self.cache = []
        self.heartbeat_interval = 30
        self.reconnect_interval = 5

    def connect(self):
        self.ws = websocket.WebSocketApp(self.url,
                                         on_message=self.on_message,
                                         on_error=self.on_error,
                                         on_close=self.on_close)
        self.ws.on_open = self.on_open
        self.ws.run_forever()

    def on_open(self, ws):
        print("WebSocket connection established.")
        self.send_cache()
        self.start_heartbeat()

    def on_message(self, ws, message):
        print("Received message: {}".format(message))

    def on_error(self, ws, error):
        print("WebSocket error: {}".format(error))

    def on_close(self, ws):
        print("WebSocket connection closed.")
        self.stop_heartbeat()
        time.sleep(self.reconnect_interval)
        self.connect()

    def start_heartbeat(self):
        self.heartbeat_timer = threading.Timer(self.heartbeat_interval, self.send_heartbeat)
        self.heartbeat_timer.start()

    def stop_heartbeat(self):
        self.heartbeat_timer.cancel()

    def send_heartbeat(self):
        self.ws.send("heartbeat")
        self.start_heartbeat()

    def send_cache(self):
        for message in self.cache:
            self.ws.send(message)
        self.cache = []

    def send_message(self, message):
        if self.ws and self.ws.sock and self.ws.sock.connected:
            self.ws.send(message)
        else:
            self.cache.append(message)

if __name__ == "__main__":
    ws_cache = WebSocketCache("wss://example.com")
    ws_cache.connect()

这个代码使用了websocket库来建立websocket连接，并实现了一个缓存机制，当websocket连接断开时，缓存的消息会被重新发送。同时，还实现了一个心跳机制，每隔一定时间会向服务器发送一个心跳消息，以保持连接。