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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.

该协议是基于消息的，是一种可向浏览器发送推送通知的非常强大的工具，并且已经被用于实现聊天、回合制游戏等。它仍然使用 TCP 连接，这对于可靠性有好处但对于延迟不利，因此不适合实时应用，如 VoIP 和快节奏的游戏（有关这些用例，请参阅 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 在原生导出和 HTML5 导出中都支持 WebSocket。

在 Godot 中使用 WebSocket

WebSocket is implemented in Godot via WebSocketPeer. The WebSocket implementation is compatible with the High-Level Multiplayer. See section on high-level multiplayer for more details.

警告

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，Android 系统会阻止该程序任何形式的网络通信。

最小客户端示例

这个示例演示的是如何建立与远程服务器的 WebSocket 连接，以及如何收发数据。

extends Node

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

# Our WebSocketClient instance.
var socket = WebSocketPeer.new()

func _ready():
    # Initiate connection to the given URL.
    var err = socket.connect_to_url(websocket_url)
    if err != OK:
        print("Unable to connect")
        set_process(false)
    else:
        # Wait for the socket to connect.
        await get_tree().create_timer(2).timeout

        # Send data.
        socket.send_text("Test packet")

func _process(_delta):
    # Call this in _process or _physics_process. Data transfer and state updates
    # will only happen when calling this function.
    socket.poll()

    # get_ready_state() tells you what state the socket is in.
    var state = socket.get_ready_state()

    # WebSocketPeer.STATE_OPEN means the socket is connected and ready
    # to send and receive data.
    if state == WebSocketPeer.STATE_OPEN:
        while socket.get_available_packet_count():
            print("Got data from server: ", socket.get_packet().get_string_from_utf8())

    # WebSocketPeer.STATE_CLOSING means the socket is closing.
    # It is important to keep polling for a clean close.
    elif state == WebSocketPeer.STATE_CLOSING:
        pass

    # WebSocketPeer.STATE_CLOSED means the connection has fully closed.
    # It is now safe to stop polling.
    elif state == WebSocketPeer.STATE_CLOSED:
        # The code will be -1 if the disconnection was not properly notified by the remote peer.
        var code = socket.get_close_code()
        print("WebSocket closed with code: %d. Clean: %s" % [code, code != -1])
        set_process(false) # Stop processing.

这个示例会打印类似这样的内容：

Got data from server: Request served by 7811941c69e658
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.client_connected.connect(_connected)
    _server.client_disconnected.connect(_disconnected)
    _server.client_close_request.connect(_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.data_received.connect(_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

A more advanced chat demo which optionally uses the multiplayer mid-level abstraction and a high-level multiplayer demo are available in the godot demo projects under networking/websocket_chat and networking/websocket_multiplayer.