#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtNetwork>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    tcpServer = new QTcpServer(this);
    //使用了IPv4的本地主机地址，等价于QHostAddress("127.0.0.1")
    if(!tcpServer->listen(QHostAddress::LocalHost, 6666)) {
        qDebug()<<tcpServer->errorString();
        close();
    }
    connect(tcpServer, SIGNAL(newConnection()), this, SLOT(sendMessage()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::sendMessage()
{
    //用于暂存要发送的数据
    QByteArray block;
    QDataStream out(&block, QIODevice::WriteOnly);

    //设置数据流的版本，客户端和服务器端使用的版本要相同
    out.setVersion(QDataStream::Qt_4_0);
    out<<(quint16)0;                            //用两个字节表示数据长度
    out<<tr("hello TCP!!!");
    out.device()->seek(0);
    out<<(quint16)(block.size() - sizeof(quint16));     //总数据大小减去数据块开头两个字节大小

    //获取已建立的连接的套接字
    QTcpSocket *clientConnection = tcpServer->nextPendingConnection();
    connect(clientConnection, SIGNAL(disconnected()), clientConnection, SLOT(deleteLater()));       //失去连接后删除
    clientConnection->write(block);
    clientConnection->disconnectFromHost();         //等待数据发送完毕后关闭

    //发送数据成功后，显示提示
    ui->label->setText("send message successful!!!");
}

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtNetwork>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    tcpSocket = new QTcpSocket(this);
    connect(tcpSocket, SIGNAL(readyRead()), this, SLOT(readMessage()));
    connect(tcpSocket, SIGNAL(error(QAbstractSocket::SocketError)),
            this, SLOT(displayError(QAbstractSocket::SocketError)));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::newConnect()
{
    //初始化数据大小信系为0
    blockSize = 0;

    //取消已有的连接
    tcpSocket->abort();
    tcpSocket->connectToHost(ui->hostLineEdit->text(), ui->portLineEdit->text().toInt());
}

void MainWindow::readMessage()
{
    QDataStream in(tcpSocket);
    //设置数据流版本，这里要和服务器端相同
    in.setVersion(QDataStream::Qt_4_6);

    //如果是刚开始接收数据
    if(blockSize == 0) {
        //判断接收的数据是否大于两个字节，也就是文件的大小信息所占的空间
        //如果是则保存到blockSize变量中，否则直接返回，继续接收数据
        if(tcpSocket->bytesAvailable()<(int)sizeof(quint16)) return;
        in>>blockSize;
    }
    //如果没有得到全部的数据，则返回，继续接收数据
    if(tcpSocket->bytesAvailable() < blockSize) return;
    //将接收到的数据存放到变量中
    in>>message;
    //显示接收到的数据
    qDebug()<<message;
    ui->messageLabel->setText(message);
}

void MainWindow::displayError(QAbstractSocket::SocketError)
{
    qDebug()<<tcpSocket->errorString();
}

void MainWindow::on_connectButton_clicked()
{
    newConnect();
}