javascript之ProtoBuf在websocket中的使用

標籤：java

因為ProtoBuf的序列化效率和大小都非常好，所以它在網路通訊上面應用越來越多；而webosocket也隨著web3.0應用越來越廣泛，而將這兩個結合在一起的也會慢慢形成一種趨勢；本人是為了測試自已寫的一個C# websocket，所以在web上面結合pb也寫了一個js執行個體:

1.首先下載protobuf.js

2.引入protobuf相關js檔案

<script src="/js/protobuf.js"></script>

3.建立proto檔案

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1 package wenlipackage;2 syntax = "proto3";3 4 message WSMessage {  5     required string id = 1;6     required string content = 2;7     required string sender = 3;8     required string time = 4;9 }

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js的protobuf格式類型有

 

Field type	Expected JS type (create, encode)	Conversion (fromObject)
s-/u-/int32 s-/fixed32	number (32 bit integer)	value | 0 if signed value >>> 0 if unsigned
s-/u-/int64 s-/fixed64	Long-like (optimal) number (53 bit integer)	Long.fromValue(value) with long.js parseInt(value, 10) otherwise
float double	number	Number(value)
bool	boolean	Boolean(value)
string	string	String(value)
bytes	Uint8Array (optimal) Buffer (optimal under node) Array.<number> (8 bit integers)	base64.decode(value) if a string Object with non-zero .length is assumed to be buffer-like
enum	number (32 bit integer)	Looks up the numeric id if a string
message	Valid message	Message.fromObject(value)

 4.初始化protobuf，對相關資料進行序列化和還原序列化

 

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 1 <script type="text/javascript"> 2         var WSMessage; 3         var wsmessage; 4         var buffer; 5         protobuf.load("/proto/Message.proto", function (err, root) { 6             if (err) throw err; 7             WSMessage = root.lookup("wenlipackage.WSMessage"); 8             wsmessage = WSMessage.create({ id: "1", content: "hello", sender: "web", time: new Date().getTime() }); 9             buffer = WSMessage.encode(wsmessage).finish();10         });11 </script>

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WSMessage是一個解碼編碼器

wsmessage是具體的某個定義的proto執行個體是一個8位無符號的位元組數組

5.串連到websocket並發送序列化的訊息和接收還原序列化的訊息

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 1 <script type="text/javascript"> 2         var wsUri = "ws://127.0.0.1:8082/"; 3         var output; 4         function init() { 5             output = document.getElementById("output"); 6             testWebSocket(); 7         } 8         function testWebSocket() { 9             websocket = new WebSocket(wsUri);10             websocket.onopen = function (evt) {11                 onOpen(evt)12             };13             websocket.onclose = function (evt) {14                 onClose(evt)15             };16             websocket.onmessage = function (evt) {17                 onMessage(evt)18             };19             websocket.onerror = function (evt) {20                 onError(evt)21             };22         }23         function onOpen(evt) {24             writeToScreen("CONNECTED");25             doSend(buffer);26         }27         function onClose(evt) {28             writeToScreen("DISCONNECTED");29         }30         function onMessage(evt) {31             var reader = new FileReader();32             reader.readAsArrayBuffer(evt.data);33             reader.onload = function (e) {34                 var buf = new Uint8Array(reader.result);35                 writeToScreen(‘<span style="color: blue;">RESPONSE: ‘ + WSMessage.decode(buf).content + ‘</span>‘);36             }37         }38         function onError(evt) {39             writeToScreen(‘<span style="color: red;">ERROR:</span> ‘ + evt.data);40         }41         function doSend(message) {42             writeToScreen("SENT: " + wsmessage.content);43             websocket.send(buffer);44         }45         function writeToScreen(message) {46             var pre = document.createElement("p");47             pre.style.wordWrap = "break-word";48             pre.innerHTML = message;49             output.appendChild(pre);50         }51         window.addEventListener("load", init, false);52 </script>

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 上面因為我的websocket server 返回一是二進位，所以瀏覽器接收到的是一個blob，這裡注意對blob的處理

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6.互連測試

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javascript之ProtoBuf在websocket中的使用