WebSocket

HTML5 与 WebSocket

WebSocket协议在2011年被标准化, 最初的目标是让浏览器与服务器建立稳定的双向连接. 在此之前, 浏览器曾只支持HTTPRequests, 并不适合双向通信.

这个协议相当简单, 基于消息, 是一个非常强大的向浏览器推送通知的工具, 已经被用来实现聊天, 回合制游戏等. 它仍使用TCP连接, 这对可靠性有好处, 但对延迟没有好处, 所以不适合实时的应用, 比如VoIP和快节奏的游戏(这些用例见 WebRTC).

由于它的简单性, 广泛的兼容性以及比原始TCP连接更容易使用,WebSocket很快就开始在浏览器以外的地方应用, 在本地应用程序中作为与网络服务器通信的一种手段.

Godot在本机和HTML5导出中都支持WebSocket.

在 Godot 中使用 WebSocket

在Godot中,WebSocket通过三个主要类来实现 WebSocketClient, WebSocketServer, 和 WebSocketPeer.WebSocket的实现与高级多人游戏兼容. 更多细节请参见 high-level multiplayer 一节.

警告

当导出到 Android 时，在导出项目或使用一键部署之前，确保在 Android 导出预设中启用 INTERNET 权限。否则，任何形式的网络通信都会被 Android 系统阻止。

最小客户端示例

本示例将向您展示如何创建与远程服务器的 WebSocket 连接, 以及如何发送和接收数据.

extends Node

# The URL we will connect to
export var websocket_url = "wss://libwebsockets.org"

# Our WebSocketClient instance
var _client = WebSocketClient.new()

func _ready():
    # Connect base signals to get notified of connection open, close, and errors.
    _client.connect("connection_closed", self, "_closed")
    _client.connect("connection_error", self, "_closed")
    _client.connect("connection_established", self, "_connected")
    # This signal is emitted when not using the Multiplayer API every time
    # a full packet is received.
    # Alternatively, you could check get_peer(1).get_available_packets() in a loop.
    _client.connect("data_received", self, "_on_data")

    # Initiate connection to the given URL.
    var err = _client.connect_to_url(websocket_url, ["lws-mirror-protocol"])
    if err != OK:
        print("Unable to connect")
        set_process(false)

func _closed(was_clean = false):
    # was_clean will tell you if the disconnection was correctly notified
    # by the remote peer before closing the socket.
    print("Closed, clean: ", was_clean)
    set_process(false)

func _connected(proto = ""):
    # This is called on connection, "proto" will be the selected WebSocket
    # sub-protocol (which is optional)
    print("Connected with protocol: ", proto)
    # You MUST always use get_peer(1).put_packet to send data to server,
    # and not put_packet directly when not using the MultiplayerAPI.
    _client.get_peer(1).put_packet("Test packet".to_utf8())

func _on_data():
    # Print the received packet, you MUST always use get_peer(1).get_packet
    # to receive data from server, and not get_packet directly when not
    # using the MultiplayerAPI.
    print("Got data from server: ", _client.get_peer(1).get_packet().get_string_from_utf8())

func _process(delta):
    # Call this in _process or _physics_process. Data transfer, and signals
    # emission will only happen when calling this function.
    _client.poll()

这将打印:

Connected with protocol:
Got data from server: Test packet

最小服务器示例

这个例子将告诉你如何创建一个监听远程连接的WebSocket服务器，以及如何发送和接收数据。

extends Node

# The port we will listen to
const PORT = 9080
# Our WebSocketServer instance
var _server = WebSocketServer.new()

func _ready():
    # Connect base signals to get notified of new client connections,
    # disconnections, and disconnect requests.
    _server.connect("client_connected", self, "_connected")
    _server.connect("client_disconnected", self, "_disconnected")
    _server.connect("client_close_request", self, "_close_request")
    # This signal is emitted when not using the Multiplayer API every time a
    # full packet is received.
    # Alternatively, you could check get_peer(PEER_ID).get_available_packets()
    # in a loop for each connected peer.
    _server.connect("data_received", self, "_on_data")
    # Start listening on the given port.
    var err = _server.listen(PORT)
    if err != OK:
        print("Unable to start server")
        set_process(false)

func _connected(id, proto):
    # This is called when a new peer connects, "id" will be the assigned peer id,
    # "proto" will be the selected WebSocket sub-protocol (which is optional)
    print("Client %d connected with protocol: %s" % [id, proto])

func _close_request(id, code, reason):
    # This is called when a client notifies that it wishes to close the connection,
    # providing a reason string and close code.
    print("Client %d disconnecting with code: %d, reason: %s" % [id, code, reason])

func _disconnected(id, was_clean = false):
    # This is called when a client disconnects, "id" will be the one of the
    # disconnecting client, "was_clean" will tell you if the disconnection
    # was correctly notified by the remote peer before closing the socket.
    print("Client %d disconnected, clean: %s" % [id, str(was_clean)])

func _on_data(id):
    # Print the received packet, you MUST always use get_peer(id).get_packet to receive data,
    # and not get_packet directly when not using the MultiplayerAPI.
    var pkt = _server.get_peer(id).get_packet()
    print("Got data from client %d: %s ... echoing" % [id, pkt.get_string_from_utf8()])
    _server.get_peer(id).put_packet(pkt)

func _process(delta):
    # Call this in _process or _physics_process.
    # Data transfer, and signals emission will only happen when calling this function.
    _server.poll()

这将打印(当客户端连接时)与此类似的东西:

Client 1348090059 connected with protocol: selected-protocol
Got data from client 1348090059: Test packet ... echoing

高级聊天演示

在 godot demo projects 下 networking/websocket_chat 和 networking/websocket_multiplayer 有一个更高级的聊天演示demo, 可以选择使用多人中级抽象和高级多人演示demo.