最近要用到Qt的Socket部分，網上關於這部分的資料都比較複雜，我在這總結一下，把Socket的主要部分提取出來，實現TCP和UDP的簡單通訊。

1.UDP通訊

UDP沒有特定的server端和client端，簡單來說就是向特定的ip傳送報文，因此我把它分為傳送端和接收端。 注意：在.pro檔案中要新增QT += network，否則無法使用Qt的網路功能。

1.1.UDP傳送端

1. #include<QtNetwork>
2. QUdpSocket*sender;
3. sender =newQUdpSocket(this);
4. QByteArray datagram =“hello world
   !”;
5. //UDP廣播
6. sender->writeDatagram(datagram.data(),datagram.size(),QHostAddress::Broadcast,6665);
7. //向特定IP傳送
8. QHostAddress serverAddress =QHostAddress("10.21.11.66");
9. sender->writeDatagram(datagram.data(), datagram.size(),serverAddress,6665);
10. /* writeDatagram函式原型，傳送成功返回位元組數，否則-1
11. qint64 writeDatagram(const char *data,qint64 size,const QHostAddress &address,quint16 port)
12. qint64 writeDatagram(const QByteArray &datagram,const QHostAddress &host,quint16 port)
13. */

1.2.UDP接收端

1. #include<QtNetwork>
2. QUdpSocket*receiver;
3. //訊號槽
4. private slots:
5. void readPendingDatagrams();
6. receiver =newQUdpSocket(this);
7. receiver->bind(QHostAddress::LocalHost,6665);
8. connect(receiver, SIGNAL
   (readyRead()),this, SLOT(readPendingDatagrams()));
9. void readPendingDatagrams()
10. {
11. while(receiver->hasPendingDatagrams()){
12. QByteArray datagram;
13. datagram.resize(receiver->pendingDatagramSize());
14. receiver->readDatagram(datagram.data(), datagram.size());
15. //資料接收在datagram裡
16. /* readDatagram 函式原型
17. qint64 readDatagram(char *data,qint64 maxSize,QHostAddress *address=0,quint16 *port=0)
18. */
19. }
20. }

2.TCP通訊

TCP的話要複雜點，必須先建立連線才能傳輸資料，分為server端和client端。

2.1.TCP client端

1. #include<QtNetwork>
2. QTcpSocket*client;
3. char*data="hello qt!";
4. client =newQTcpSocket(this);
5. client->connectToHost(QHostAddress("10.21.11.66"),6665);
6. client->write(data);

2.2.TCP server端

1. #include<QtNetwork>
2. QTcpServer*server;
3. QTcpSocket*clientConnection;
4. server =newQTcpServer();
5. server->listen(QHostAddress::Any,6665);
6. connect(server, SIGNAL(newConnection()),this, SLOT(acceptConnection()));
7. void acceptConnection()
8. {
9. clientConnection = server->nextPendingConnection();
10. connect(clientConnection, SIGNAL(readyRead()),this, SLOT(readClient()));
11. }
12. void readClient()
13. {
14. QString str = clientConnection->readAll();
15. //或者
16. char buf[1024];
17. clientConnection->read(buf,1024);
18. }