《Lua游戏开发实战》6.4 网络通信的基础实现

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-- HTTP示例：获取排行榜数据
local function fetch_leaderboard()
    http.request("https://api.game.com/leaderboard", "GET", function(self, id, response)
        if response.status == 200 then
            local data = json.decode(response.response)
            update_ui(data)
        end
    end)
end

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local headers = {
    ["Content-Type"] = "application/json",
    ["Authorization"] = "Bearer " .. access_token
}

http.request("https://api.game.com/save", "POST", function(...) end, headers, json.encode(save_data))

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local TIMEOUT = 10 -- 秒
local retries = 3

local function safe_request(url, method, callback)
    local request_id = http.request(url, method, function(...)
        retries = 0
        callback(...)
    end)

    timer.delay(TIMEOUT, false, function()
        if retries > 0 then
            retries = retries - 1
            http.cancel(request_id)
            safe_request(url, method, callback)
        end
    end)
end

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local boundary = "BOUNDARY12345"
local body = 
    "--" .. boundary .. "\r\n" ..
    "Content-Disposition: form-data; name=\"file\"; filename=\"screenshot.jpg\"\r\n" ..
    "Content-Type: image/jpeg\r\n\r\n" ..
    sys.load_resource("/images/screenshot.jpg") .. "\r\n" ..
    "--" .. boundary .. "--"

http.request("https://api.game.com/upload", "POST", function() end, {
    ["Content-Type"] = "multipart/form-data; boundary=" .. boundary
}, body)

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local ws = websocket.create("wss://game-server.com/ws")

websocket.listen(ws, {
    on_message = function(self, message)
        if message.type == websocket.MESSAGE_TYPE_TEXT then
            handle_server_message(json.decode(message.data))
        end
    end,
    on_close = function(self)
        show_reconnect_ui()
    end
})

-- 心跳检测
timer.delay(5, true, function()
    websocket.send(ws, json.encode({type = "ping"}))
end)

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-- 使用MessagePack压缩数据
local packed = msgpack.pack({
    pos = {x=10.5, y=3.2},
    action = "jump",
    timestamp = socket.gettime()
})

websocket.send_binary(ws, packed)

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local SEND_RATE = 0.1 -- 100ms
local message_queue = {}

timer.delay(SEND_RATE, true, function()
    if #message_queue > 0 then
        local batch = {messages = message_queue}
        websocket.send(ws, json.encode(batch))
        message_queue = {}
    end
end)

function queue_message(msg)
    table.insert(message_queue, msg)
end

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-- 位置同步协议示例：
-- [1字节类型][4字节x][4字节y][4字节时间戳]

function serialize_position(x, y)
    local buffer = buffer.create(13)
    buffer.write_byte(buffer, 0x01)
    buffer.write_int32(buffer, x * 100) -- 精度0.01
    buffer.write_int32(buffer, y * 100)
    buffer.write_int32(buffer, socket.gettime() * 1000)
    return buffer.get_bytes(buffer)
end

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-- 自定义证书验证回调
http.set_verify_callback(function(hostname, cert)
    return cert:match("CN=trusted%.game%.com")
end)

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local crypto = require("crypto")

function encrypt(data, key)
    local iv = crypto.random(16)
    local cipher = crypto.encrypt_aes256_cbc(data, key, iv)
    return iv .. cipher
end

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function sign_request(data, secret)
    local timestamp = tostring(socket.gettime())
    local signature = crypto.hmac_sha256(data .. timestamp, secret)
    return {
        data = data,
        timestamp = timestamp,
        sig = signature
    }
end

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-- 客户端预测 + 服务器校验
function apply_prediction(current_pos, server_pos, latency)
    local blend_factor = latency * 0.5
    return {
        x = current_pos.x * blend_factor + server_pos.x * (1 - blend_factor),
        y = current_pos.y * blend_factor + server_pos.y * (1 - blend_factor)
    }
end

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local RECONNECT_INTERVAL = {5, 10, 30} -- 渐进重试间隔

function reconnect(attempt)
    attempt = attempt or 1
    if attempt > #RECONNECT_INTERVAL then return end
    
    websocket.connect(ws)
    
    websocket.listen(ws, {
        on_open = function()
            -- 发送断线期间的关键状态
            send_catchup_data()
        end,
        on_close = function()
            timer.delay(RECONNECT_INTERVAL[attempt], function()
                reconnect(attempt + 1)
            end)
        end
    })
end

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function draw_network_debug()
    local stats = websocket.get_stats(ws)
    gui.text("Ping: " .. stats.ping .. "ms")
    gui.text("Packet Loss: " .. stats.packet_loss .. "%")
    gui.plot_graph("Bandwidth", stats.bytes_sent, stats.bytes_received)
end

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-- 服务器推送更新
websocket.listen(ws, {
    on_message = function(self, msg)
        if msg.type == "leaderboard_update" then
            table.sort(msg.entries, function(a,b) return a.score > b.score end)
            gui.update_leaderboard(msg.entries)
        end
    end
})

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-- 状态快照插值
local server_states = {}
function on_snapshot_received(snapshot)
    table.insert(server_states, {
        time = socket.gettime(),
        data = snapshot
    })
    
    -- 保留最近3个快照进行插值
    if #server_states > 3 then
        table.remove(server_states, 1)
    end
end

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-- 消息分通道处理
local CHANNELS = {
    world = true,
    guild = true,
    private = function(msg)
        return msg.target == player_id
    end
}

function handle_chat_message(msg)
    local channel = CHANNELS[msg.channel]
    if type(channel) == "function" and channel(msg) then
        show_chat_message(msg)
    elseif channel == true then
        show_chat_message(msg)
    end
end

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function verify_nft(token_id)
    local response = http.request("https://api.opensea.io/api/v1/asset/"..token_id)
    return response.owner == player_wallet_address
end