Qt文档阅读笔记-Simple Chat Example解析
这个实例使用QWebSocket和QWebSocketServer去构造WebSocket协议的极简聊天室。
官方对于这个实例给出的文档方面的介绍就这么多，下面是对应的代码，我自己补充下：
文件一共如下：
我们由简入深分析下，首先是simplechat.pro
QT = websockets
TARGET = chatserver
CONFIG += console
CONFIG -= app_bundle
TEMPLATE = app
SOURCES += \
main.cpp \
chatserver.cpp
HEADERS += \
chatserver.h
EXAMPLE_FILES += chatclient.html
target.path = $$[QT_INSTALL_EXAMPLES]/websockets/simplechat
INSTALLS += target这里主要是包含websockets模块，使用的语法是 QT = websockets
main.cpp就是实例化ChatServer在此不再说明。
下面是chartserver.h和chartserver.cpp
#ifndef CHATSERVER_H
#define CHATSERVER_H
#include <QtCore/QObject>
#include <QtCore/QList>
QT_FORWARD_DECLARE_CLASS(QWebSocketServer)
QT_FORWARD_DECLARE_CLASS(QWebSocket)
QT_FORWARD_DECLARE_CLASS(QString)
class ChatServer : public QObject
{
Q_OBJECT
public:
explicit ChatServer(quint16 port, QObject *parent = nullptr);
~ChatServer() override;
private slots:
void onNewConnection();
void processMessage(const QString &message);
void socketDisconnected();
private:
QWebSocketServer *m_pWebSocketServer;
QList<QWebSocket *> m_clients;
};
#endif //CHATSERVER_H#include "chatserver.h"
#include <QtWebSockets>
#include <QtCore>
#include <cstdio>
using namespace std;
QT_USE_NAMESPACE
static QString getIdentifier(QWebSocket *peer)
{
return QStringLiteral("%1:%2").arg(peer->peerAddress().toString(),
QString::number(peer->peerPort()));
}
//! [constructor]
ChatServer::ChatServer(quint16 port, QObject *parent) :
QObject(parent),
m_pWebSocketServer(new QWebSocketServer(QStringLiteral("Chat Server"),
QWebSocketServer::NonSecureMode,
this))
{
if (m_pWebSocketServer->listen(QHostAddress::Any, port))
{
QTextStream(stdout) << "Chat Server listening on port " << port << '\n';
connect(m_pWebSocketServer, &QWebSocketServer::newConnection,
this, &ChatServer::onNewConnection);
}
}
ChatServer::~ChatServer()
{
m_pWebSocketServer->close();
}
//! [constructor]
//! [onNewConnection]
void ChatServer::onNewConnection()
{
auto pSocket = m_pWebSocketServer->nextPendingConnection();
QTextStream(stdout) << getIdentifier(pSocket) << " connected!\n";
pSocket->setParent(this);
connect(pSocket, &QWebSocket::textMessageReceived,
this, &ChatServer::processMessage);
connect(pSocket, &QWebSocket::disconnected,
this, &ChatServer::socketDisconnected);
m_clients << pSocket;
}
//! [onNewConnection]
//! [processMessage]
void ChatServer::processMessage(const QString &message)
{
QWebSocket *pSender = qobject_cast<QWebSocket *>(sender());
for (QWebSocket *pClient : qAsConst(m_clients)) {
if (pClient != pSender) //don't echo message back to sender
pClient->sendTextMessage(message);
}
}
//! [processMessage]
//! [socketDisconnected]
void ChatServer::socketDisconnected()
{
QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());
QTextStream(stdout) << getIdentifier(pClient) << " disconnected!\n";
if (pClient)
{
m_clients.removeAll(pClient);
pClient->deleteLater();
}
}
//! [socketDisconnected]这里解释几个点：
①m_pWebSocketServer是QWebSocketServer，指定其名和mode以及开通的端口号；
②newConnection中，使用m_pWebSocketServer获取nextPendingConnection，然后得到这个与客户端相连的socket后，设置信号与槽。
③processMessage，将获取到用户发来的信号与槽，发送给所有连接到服务器的用户。
④socketDisconnect，当用户断开连接后，把其用户移除m_clients。
下面是chartclient.html
<html>
<head>
<title>WebSocket Chat Client</title>
</head>
<body>
<h1>WebSocket Chat Client</h1>
<p>
Host: <input id="webSocketHost" type="text" value="localhost:1234"/>
</p>
<p>
<button onClick="initWebSocket();">Connect</button>
<button id="disconnectButton" onClick="stopWebSocket();" disabled>Disconnect</button>
<button onClick="checkSocket();">State</button>
</p>
<p>
<textarea id="debugTextArea" style="width:400px;height:200px;" readonly></textarea>
</p>
<p>
<input type="text" id="inputNick" value="nickname" />
<input type="text" id="inputText" onkeydown="if(event.keyCode==13)sendMessage();"/>
<button id="sendButton" onClick="sendMessage();" disabled>Send</button>
</p>
<script type="text/javascript">
var debugTextArea = document.getElementById("debugTextArea");
function debug(message) {
debugTextArea.value += message + "\n";
debugTextArea.scrollTop = debugTextArea.scrollHeight;
}
function sendMessage() {
var nickname = document.getElementById("inputNick").value;
var msg = document.getElementById("inputText").value;
var strToSend = nickname + ": " + msg;
if ( websocket != null )
{
document.getElementById("inputText").value = "";
websocket.send( strToSend );
console.log( "string sent :", '"'+strToSend+'"' );
debug(strToSend);
}
}
var websocket = null;
function initWebSocket() {
try {
if (typeof MozWebSocket == 'function')
WebSocket = MozWebSocket;
if ( websocket && websocket.readyState == 1 )
websocket.close();
var wsUri = "ws://" + document.getElementById("webSocketHost").value;
websocket = new WebSocket( wsUri );
websocket.onopen = function (evt) {
debug("CONNECTED");
document.getElementById("disconnectButton").disabled = false;
document.getElementById("sendButton").disabled = false;
};
websocket.onclose = function (evt) {
debug("DISCONNECTED");
document.getElementById("disconnectButton").disabled = true;
document.getElementById("sendButton").disabled = true;
};
websocket.onmessage = function (evt) {
console.log( "Message received :", evt.data );
debug( evt.data );
};
websocket.onerror = function (evt) {
debug('ERROR: ' + evt.data);
};
} catch (exception) {
debug('ERROR: ' + exception);
}
}
function stopWebSocket() {
if (websocket)
websocket.close();
}
function checkSocket() {
if (websocket != null) {
var stateStr;
switch (websocket.readyState) {
case 0: {
stateStr = "CONNECTING";
break;
}
case 1: {
stateStr = "OPEN";
break;
}
case 2: {
stateStr = "CLOSING";
break;
}
case 3: {
stateStr = "CLOSED";
break;
}
default: {
stateStr = "UNKNOW";
break;
}
}
debug("WebSocket state = " + websocket.readyState + " ( " + stateStr + " )");
} else {
debug("WebSocket is null");
}
}
</script>
</body>
</html>这个html代码，浏览器运行后，会创建一个websocket连接到服务端上，然后进行文本串的交互。
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