【整理】html5知識點5
阿新 • • 發佈：2019-01-29
============================================HTML5 WebSocket
什麼是websocket
WebSocket 協議是html5引入的一種新的協議，其目的在於實現了瀏覽器與伺服器全雙工通訊。看了上面連結的同學肯定對過去怎麼低效率高消耗（輪詢或comet）的做此事已經有所瞭解了，而在websocket API，瀏覽器和伺服器只需要要做一個握手的動作，然後，瀏覽器和伺服器之間就形成了一條快速通道。兩者之間就直接可以資料互相傳送。同時這麼做有兩個好處
1.通訊傳輸位元組減少：比起以前使用http傳輸資料，websocket傳輸的額外資訊很少，據百度說只有2k
2.伺服器可以主動向客戶端推送訊息，而不用客戶端去查詢
握手
除了TCP連線的三次握手，websocket協議中客戶端與伺服器想建立連線需要一次額外的握手動作，在最新版的協議中是這個樣子的
客戶端向伺服器傳送請求
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: 127.0.0.1:8080
Origin: http://test.com
Pragma: no-cache
Cache-Control: no-cache
Sec-WebSocket-Key: OtZtd55qBhJF2XLNDRgUMg==
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: x-webkit-deflate-frame
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36
伺服器給出響應
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: xsOSgr30aKL2GNZKNHKmeT1qYjA=
在請求中的“Sec-WebSocket-Key”是隨機的，伺服器端會用這些資料來構造出一個SHA-1的資訊摘要。把“Sec-WebSocket-Key”加上一個魔幻字串“258EAFA5-E914-47DA-95CA-C5AB0DC85B11”。使用 SHA-1 加密，之後進行 BASE-64編碼，將結果做為 “Sec-WebSocket-Accept” 頭的值，返回給客戶端
websocket API
經過握手之後瀏覽器與伺服器建立連線，兩者就可以互相通訊了。websocket的API真心很簡單，看看 W3C 的定義
tring url, optional (DOMString or DOMString[]) protocols)]
interface WebSocket : EventTarget {
readonly attribute DOMString url;
// ready state
const unsigned short CONNECTING = 0;
const unsigned short OPEN = 1;
const unsigned short CLOSING = 2;
const unsigned short CLOSED = 3;
readonly attribute unsigned short readyState;
readonly attribute unsigned long bufferedAmount;
// networking
attribute EventHandler onopen;
attribute EventHandler onerror;
attribute EventHandler onclose;
readonly attribute DOMString extensions;
readonly attribute DOMString protocol;
void close([Clamp] optional unsigned short code, optional DOMString reason);
// messaging
attribute EventHandler onmessage;
attribute BinaryType binaryType;
void send(DOMString data);
void send(Blob data);
void send(ArrayBuffer data);
void send(ArrayBufferView data);
};
==================================================
建立websocket
ws=new WebSocket(address); //ws://127.0.0.1:8080
呼叫其建構函式，傳入地址，就可以建立一個websocket了，值得注意的是地址協議得是ws/wss
關閉socket
ws.close();
呼叫webservice例項的close()方法就可以關閉webservice，當然也可以傳入一個code和string說明為什麼關了
幾個回撥函式控制代碼
由於其非同步執行，回撥函式自然少不了，有四個重要的
onopen：連線建立後呼叫
onmessage：接收到伺服器訊息後呼叫
onerror：出錯時呼叫
onclose：關閉連線的時候呼叫
看名字就知道是幹什麼的了，每個回撥函式都會傳入一個Event物件，可以通過event.data訪問訊息
使用API
我們可以在建立socket成功後為其回撥函式賦值
ws=new WebSocket(address);
ws.onopen=function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
};
也可以通過事件繫結的方式
ws=new WebSocket(address);
ws.addEventListener('open',function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
});
============================================================================
客戶端實現
其實客戶端的實現比較簡單，除了websocket相關的幾句就是一些自動focus、回車鍵事件處理、訊息框自動定位到底部等簡單功能，不一一說明了
【demo】已驗證
頁面
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
var ws;
function ToggleConnectionClicked() {
try {
var SOCKECT_ADDR = "ws://localhost:1818/chat";
ws = new WebSocket(SOCKECT_ADDR);
ws.onopen = function (event) { alert("已經與伺服器建立了連線\r\n當前連線狀態：" + this.readyState); };
ws.onmessage = function (event) { alert("接收到伺服器傳送的資料：\r\n" + event.data); };
ws.onclose = function (event) { alert("已經與伺服器斷開連線\r\n當前連線狀態：" + this.readyState); };
ws.onerror = function (event) {alert("WebSocket異常！" + event.toString());};
} catch (ex) {
alert(ex.message);
}
};
function SendData() {
try {
ws.send("success");
} catch (ex) {
alert(ex.message);
}
};
function seestate() {
alert(ws.readyState);
}
</script>
</head>
<body>
<button id='ToggleConnection' type="button" onclick='ToggleConnectionClicked();'>
連線伺服器</button><br />
<br />
<button id='ToggleConnection' type="button" onclick='SendData();'>
傳送我的名字：beston</button><br />
<br />
<button id='ToggleConnection' type="button" onclick='seestate();'>
檢視狀態</button><br />
<br />
</body>
</html>
伺服器端控制檯程式
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
using System.Security.Cryptography;
namespace WebSocketServer
{
class Program
{
static void Main(string[] args)
{
int port = 1818;
byte[] buffer = new byte[1024];
IPEndPoint localEP = new IPEndPoint(IPAddress.Any, port);
Socket listener = new Socket(localEP.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localEP);
listener.Listen(10);
Console.WriteLine("等待客戶端連線....");
Socket sc = listener.Accept();//接受一個連線
Console.WriteLine("接受到了客戶端：" + sc.RemoteEndPoint.ToString() + "連線....");
//握手
int length = sc.Receive(buffer);//接受客戶端握手資訊
sc.Send(PackHandShakeData(GetSecKeyAccetp(buffer, length)));
Console.WriteLine("已經發送握手協議了....");
//接受客戶端資料
Console.WriteLine("等待客戶端資料....");
length = sc.Receive(buffer);//接受客戶端資訊
string clientMsg = AnalyticData(buffer, length);
Console.WriteLine("接受到客戶端資料：" + clientMsg);
//傳送資料
string sendMsg = "您好，" + clientMsg;
Console.WriteLine("傳送資料：“" + sendMsg + "” 至客戶端....");
sc.Send(PackData(sendMsg));
Console.WriteLine("演示Over!");
Console.Read();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
/// <summary>
/// 打包握手資訊
/// </summary>
/// <param name="secKeyAccept">Sec-WebSocket-Accept</param>
/// <returns>資料包</returns>
private static byte[] PackHandShakeData(string secKeyAccept)
{
var responseBuilder = new StringBuilder();
responseBuilder.Append("HTTP/1.1 101 Switching Protocols" + Environment.NewLine);
responseBuilder.Append("Upgrade: websocket" + Environment.NewLine);
responseBuilder.Append("Connection: Upgrade" + Environment.NewLine);
responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine + Environment.NewLine);
//如果把上一行換成下面兩行，才是thewebsocketprotocol-17協議，但居然握手不成功，目前仍沒弄明白！
//responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine);
//responseBuilder.Append("Sec-WebSocket-Protocol: chat" + Environment.NewLine);
return Encoding.UTF8.GetBytes(responseBuilder.ToString());
}
/// <summary>
/// 生成Sec-WebSocket-Accept
/// </summary>
/// <param name="handShakeText">客戶端握手資訊</param>
/// <returns>Sec-WebSocket-Accept</returns>
private static string GetSecKeyAccetp(byte[] handShakeBytes, int bytesLength)
{
string handShakeText = Encoding.UTF8.GetString(handShakeBytes, 0, bytesLength);
string key = string.Empty;
Regex r = new Regex(@"Sec\-WebSocket\-Key:(.*?)\r\n");
Match m = r.Match(handShakeText);
if (m.Groups.Count != 0)
{
key = Regex.Replace(m.Value, @"Sec\-WebSocket\-Key:(.*?)\r\n", "$1").Trim();
}
byte[] encryptionString = SHA1.Create().ComputeHash(Encoding.ASCII.GetBytes(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
return Convert.ToBase64String(encryptionString);
}
/// <summary>
/// 解析客戶端資料包
/// </summary>
/// <param name="recBytes">伺服器接收的資料包</param>
/// <param name="recByteLength">有效資料長度</param>
/// <returns></returns>
private static string AnalyticData(byte[] recBytes, int recByteLength)
{
if (recByteLength < 2) { return string.Empty; }
bool fin = (recBytes[0] & 0x80) == 0x80; // 1bit，1表示最後一幀
if (!fin)
{
return string.Empty;// 超過一幀暫不處理
}
bool mask_flag = (recBytes[1] & 0x80) == 0x80; // 是否包含掩碼
if (!mask_flag)
{
return string.Empty;// 不包含掩碼的暫不處理
}
int payload_len = recBytes[1] & 0x7F; // 資料長度
byte[] masks = new byte[4];
byte[] payload_data;
if (payload_len == 126)
{
Array.Copy(recBytes, 4, masks, 0, 4);
payload_len = (UInt16)(recBytes[2] << 8 | recBytes[3]);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 8, payload_data, 0, payload_len);
}
else if (payload_len == 127)
{
Array.Copy(recBytes, 10, masks, 0, 4);
byte[] uInt64Bytes = new byte[8];
for (int i = 0; i < 8; i++)
{
uInt64Bytes[i] = recBytes[9 - i];
}
UInt64 len = BitConverter.ToUInt64(uInt64Bytes, 0);
payload_data = new byte[len];
for (UInt64 i = 0; i < len; i++)
{
payload_data[i] = recBytes[i + 14];
}
}
else
{
Array.Copy(recBytes, 2, masks, 0, 4);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 6, payload_data, 0, payload_len);
}
for (var i = 0; i < payload_len; i++)
{
payload_data[i] = (byte)(payload_data[i] ^ masks[i % 4]);
}
return Encoding.UTF8.GetString(payload_data);
}
/// <summary>
/// 打包伺服器資料
/// </summary>
/// <param name="message">資料</param>
/// <returns>資料包</returns>
private static byte[] PackData(string message)
{
byte[] contentBytes = null;
byte[] temp = Encoding.UTF8.GetBytes(message);
if (temp.Length < 126)
{
contentBytes = new byte[temp.Length + 2];
contentBytes[0] = 0x81;
contentBytes[1] = (byte)temp.Length;
Array.Copy(temp, 0, contentBytes, 2, temp.Length);
}
else if (temp.Length < 0xFFFF)
{
contentBytes = new byte[temp.Length + 4];
contentBytes[0] = 0x81;
contentBytes[1] = 126;
contentBytes[2] = (byte)(temp.Length & 0xFF);
contentBytes[3] = (byte)(temp.Length >> 8 & 0xFF);
Array.Copy(temp, 0, contentBytes, 4, temp.Length);
}
else
{
// 暫不處理超長內容
}
return contentBytes;
}
}
}
什麼是websocket
WebSocket 協議是html5引入的一種新的協議，其目的在於實現了瀏覽器與伺服器全雙工通訊。看了上面連結的同學肯定對過去怎麼低效率高消耗（輪詢或comet）的做此事已經有所瞭解了，而在websocket API，瀏覽器和伺服器只需要要做一個握手的動作，然後，瀏覽器和伺服器之間就形成了一條快速通道。兩者之間就直接可以資料互相傳送。同時這麼做有兩個好處
1.通訊傳輸位元組減少：比起以前使用http傳輸資料，websocket傳輸的額外資訊很少，據百度說只有2k
2.伺服器可以主動向客戶端推送訊息，而不用客戶端去查詢
握手
除了TCP連線的三次握手，websocket協議中客戶端與伺服器想建立連線需要一次額外的握手動作，在最新版的協議中是這個樣子的
客戶端向伺服器傳送請求
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: 127.0.0.1:8080
Origin: http://test.com
Pragma: no-cache
Cache-Control: no-cache
Sec-WebSocket-Key: OtZtd55qBhJF2XLNDRgUMg==
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: x-webkit-deflate-frame
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36
伺服器給出響應
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: xsOSgr30aKL2GNZKNHKmeT1qYjA=
在請求中的“Sec-WebSocket-Key”是隨機的，伺服器端會用這些資料來構造出一個SHA-1的資訊摘要。把“Sec-WebSocket-Key”加上一個魔幻字串“258EAFA5-E914-47DA-95CA-C5AB0DC85B11”。使用 SHA-1 加密，之後進行 BASE-64編碼，將結果做為 “Sec-WebSocket-Accept” 頭的值，返回給客戶端
websocket API
經過握手之後瀏覽器與伺服器建立連線，兩者就可以互相通訊了。websocket的API真心很簡單，看看 W3C 的定義
tring url, optional (DOMString or DOMString[]) protocols)]
interface WebSocket : EventTarget {
readonly attribute DOMString url;
// ready state
const unsigned short CONNECTING = 0;
const unsigned short OPEN = 1;
const unsigned short CLOSING = 2;
const unsigned short CLOSED = 3;
readonly attribute unsigned short readyState;
readonly attribute unsigned long bufferedAmount;
// networking
attribute EventHandler onopen;
attribute EventHandler onerror;
attribute EventHandler onclose;
readonly attribute DOMString extensions;
readonly attribute DOMString protocol;
void close([Clamp] optional unsigned short code, optional DOMString reason);
// messaging
attribute EventHandler onmessage;
attribute BinaryType binaryType;
void send(DOMString data);
void send(Blob data);
void send(ArrayBuffer data);
void send(ArrayBufferView data);
};
==================================================
建立websocket
ws=new WebSocket(address); //ws://127.0.0.1:8080
呼叫其建構函式，傳入地址，就可以建立一個websocket了，值得注意的是地址協議得是ws/wss
關閉socket
ws.close();
呼叫webservice例項的close()方法就可以關閉webservice，當然也可以傳入一個code和string說明為什麼關了
幾個回撥函式控制代碼
由於其非同步執行，回撥函式自然少不了，有四個重要的
onopen：連線建立後呼叫
onmessage：接收到伺服器訊息後呼叫
onerror：出錯時呼叫
onclose：關閉連線的時候呼叫
看名字就知道是幹什麼的了，每個回撥函式都會傳入一個Event物件，可以通過event.data訪問訊息
使用API
我們可以在建立socket成功後為其回撥函式賦值
ws=new WebSocket(address);
ws.onopen=function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
};
也可以通過事件繫結的方式
ws=new WebSocket(address);
ws.addEventListener('open',function(e){
var msg=document.createElement('div');
msg.style.color='#0f0';
msg.innerHTML="Server > connection open.";
msgContainer.appendChild(msg);
ws.send('{<'+document.getElementById('name').value+'>}');
});
============================================================================
客戶端實現
其實客戶端的實現比較簡單，除了websocket相關的幾句就是一些自動focus、回車鍵事件處理、訊息框自動定位到底部等簡單功能，不一一說明了
【demo】已驗證
頁面
<!DOCTYPE html>
<html>
<head>
<title></title>
<script type="text/javascript">
var ws;
function ToggleConnectionClicked() {
try {
var SOCKECT_ADDR = "ws://localhost:1818/chat";
ws = new WebSocket(SOCKECT_ADDR);
ws.onopen = function (event) { alert("已經與伺服器建立了連線\r\n當前連線狀態：" + this.readyState); };
ws.onmessage = function (event) { alert("接收到伺服器傳送的資料：\r\n" + event.data); };
ws.onclose = function (event) { alert("已經與伺服器斷開連線\r\n當前連線狀態：" + this.readyState); };
ws.onerror = function (event) {alert("WebSocket異常！" + event.toString());};
} catch (ex) {
alert(ex.message);
}
};
function SendData() {
try {
ws.send("success");
} catch (ex) {
alert(ex.message);
}
};
function seestate() {
alert(ws.readyState);
}
</script>
</head>
<body>
<button id='ToggleConnection' type="button" onclick='ToggleConnectionClicked();'>
連線伺服器</button><br />
<br />
<button id='ToggleConnection' type="button" onclick='SendData();'>
傳送我的名字：beston</button><br />
<br />
<button id='ToggleConnection' type="button" onclick='seestate();'>
檢視狀態</button><br />
<br />
</body>
</html>
伺服器端控制檯程式
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Text.RegularExpressions;
using System.Security.Cryptography;
namespace WebSocketServer
{
class Program
{
static void Main(string[] args)
{
int port = 1818;
byte[] buffer = new byte[1024];
IPEndPoint localEP = new IPEndPoint(IPAddress.Any, port);
Socket listener = new Socket(localEP.Address.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
try
{
listener.Bind(localEP);
listener.Listen(10);
Console.WriteLine("等待客戶端連線....");
Socket sc = listener.Accept();//接受一個連線
Console.WriteLine("接受到了客戶端：" + sc.RemoteEndPoint.ToString() + "連線....");
//握手
int length = sc.Receive(buffer);//接受客戶端握手資訊
sc.Send(PackHandShakeData(GetSecKeyAccetp(buffer, length)));
Console.WriteLine("已經發送握手協議了....");
//接受客戶端資料
Console.WriteLine("等待客戶端資料....");
length = sc.Receive(buffer);//接受客戶端資訊
string clientMsg = AnalyticData(buffer, length);
Console.WriteLine("接受到客戶端資料：" + clientMsg);
//傳送資料
string sendMsg = "您好，" + clientMsg;
Console.WriteLine("傳送資料：“" + sendMsg + "” 至客戶端....");
sc.Send(PackData(sendMsg));
Console.WriteLine("演示Over!");
Console.Read();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
/// <summary>
/// 打包握手資訊
/// </summary>
/// <param name="secKeyAccept">Sec-WebSocket-Accept</param>
/// <returns>資料包</returns>
private static byte[] PackHandShakeData(string secKeyAccept)
{
var responseBuilder = new StringBuilder();
responseBuilder.Append("HTTP/1.1 101 Switching Protocols" + Environment.NewLine);
responseBuilder.Append("Upgrade: websocket" + Environment.NewLine);
responseBuilder.Append("Connection: Upgrade" + Environment.NewLine);
responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine + Environment.NewLine);
//如果把上一行換成下面兩行，才是thewebsocketprotocol-17協議，但居然握手不成功，目前仍沒弄明白！
//responseBuilder.Append("Sec-WebSocket-Accept: " + secKeyAccept + Environment.NewLine);
//responseBuilder.Append("Sec-WebSocket-Protocol: chat" + Environment.NewLine);
return Encoding.UTF8.GetBytes(responseBuilder.ToString());
}
/// <summary>
/// 生成Sec-WebSocket-Accept
/// </summary>
/// <param name="handShakeText">客戶端握手資訊</param>
/// <returns>Sec-WebSocket-Accept</returns>
private static string GetSecKeyAccetp(byte[] handShakeBytes, int bytesLength)
{
string handShakeText = Encoding.UTF8.GetString(handShakeBytes, 0, bytesLength);
string key = string.Empty;
Regex r = new Regex(@"Sec\-WebSocket\-Key:(.*?)\r\n");
Match m = r.Match(handShakeText);
if (m.Groups.Count != 0)
{
key = Regex.Replace(m.Value, @"Sec\-WebSocket\-Key:(.*?)\r\n", "$1").Trim();
}
byte[] encryptionString = SHA1.Create().ComputeHash(Encoding.ASCII.GetBytes(key + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
return Convert.ToBase64String(encryptionString);
}
/// <summary>
/// 解析客戶端資料包
/// </summary>
/// <param name="recBytes">伺服器接收的資料包</param>
/// <param name="recByteLength">有效資料長度</param>
/// <returns></returns>
private static string AnalyticData(byte[] recBytes, int recByteLength)
{
if (recByteLength < 2) { return string.Empty; }
bool fin = (recBytes[0] & 0x80) == 0x80; // 1bit，1表示最後一幀
if (!fin)
{
return string.Empty;// 超過一幀暫不處理
}
bool mask_flag = (recBytes[1] & 0x80) == 0x80; // 是否包含掩碼
if (!mask_flag)
{
return string.Empty;// 不包含掩碼的暫不處理
}
int payload_len = recBytes[1] & 0x7F; // 資料長度
byte[] masks = new byte[4];
byte[] payload_data;
if (payload_len == 126)
{
Array.Copy(recBytes, 4, masks, 0, 4);
payload_len = (UInt16)(recBytes[2] << 8 | recBytes[3]);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 8, payload_data, 0, payload_len);
}
else if (payload_len == 127)
{
Array.Copy(recBytes, 10, masks, 0, 4);
byte[] uInt64Bytes = new byte[8];
for (int i = 0; i < 8; i++)
{
uInt64Bytes[i] = recBytes[9 - i];
}
UInt64 len = BitConverter.ToUInt64(uInt64Bytes, 0);
payload_data = new byte[len];
for (UInt64 i = 0; i < len; i++)
{
payload_data[i] = recBytes[i + 14];
}
}
else
{
Array.Copy(recBytes, 2, masks, 0, 4);
payload_data = new byte[payload_len];
Array.Copy(recBytes, 6, payload_data, 0, payload_len);
}
for (var i = 0; i < payload_len; i++)
{
payload_data[i] = (byte)(payload_data[i] ^ masks[i % 4]);
}
return Encoding.UTF8.GetString(payload_data);
}
/// <summary>
/// 打包伺服器資料
/// </summary>
/// <param name="message">資料</param>
/// <returns>資料包</returns>
private static byte[] PackData(string message)
{
byte[] contentBytes = null;
byte[] temp = Encoding.UTF8.GetBytes(message);
if (temp.Length < 126)
{
contentBytes = new byte[temp.Length + 2];
contentBytes[0] = 0x81;
contentBytes[1] = (byte)temp.Length;
Array.Copy(temp, 0, contentBytes, 2, temp.Length);
}
else if (temp.Length < 0xFFFF)
{
contentBytes = new byte[temp.Length + 4];
contentBytes[0] = 0x81;
contentBytes[1] = 126;
contentBytes[2] = (byte)(temp.Length & 0xFF);
contentBytes[3] = (byte)(temp.Length >> 8 & 0xFF);
Array.Copy(temp, 0, contentBytes, 4, temp.Length);
}
else
{
// 暫不處理超長內容
}
return contentBytes;
}
}
}