为了方便网络编程，Qt 提供了 Network 模块。该模块包含了许多类，本文介绍了Qt实现FTP的上传和下载，分享给大家

本来想简单抄抄书，随便手写个Ftp客户端的，结果发现教材上的是基于Qt4的QFtp类库，而在Qt5中取消了这一个类库（同时也取消了QHttp等的类），取而代之的是QNetworkAccessManager 这个类，把这些杂货全都揽下来了，据说是因为之前的两个类有重复而且效率有问题balabala。于是就百度了一下，发现百度上要么讲的不全，要么就是要去下一个由热心网民重新封装的QFtp类。显然我并不喜欢无脑复制粘贴，想好好看下Qt官方提供的东西的用法，深入的理解下Qt网络编程，于是就果断自行google（话说google真好用），加上查看帮助文档，终于把一个简版的Ftp客户端大概框架弄清楚了。

不多说，上源码：

Dialog.pro

#-------------------------------------------------## Project created by QtCreator 2015-10-29T23:52:56##-------------------------------------------------QT += core guiQT += network #这里要添加这个库greaterThan(QT_MAJOR_VERSION, 4): QT += widgetsTARGET = QFtpTEMPLATE = appSOURCES += main.cpp dialog.cppHEADERS += dialog.h

dialog.h

#ifndef DIALOG_H#define DIALOG_H//注意需要添加的头文件#include<QDialog>#include<QPushButton>#include<QFile>#include<QNetworkReply>#include<QLineEdit>#include<QtNetwork/QNetworkAccessManager>#include<QtNetwork/QNetworkRequest>#include<QLabel>#include<QString>#include<QGridLayout>#include<QMessageBox>class Dialog : public QDialog{ Q_OBJECTpublic: Dialog(QWidget *parent = 0); ~Dialog();public: QGridLayout *layout; QLabel *LbServer,*LbUser,*LbPasswd; QLineEdit *LeServer,*LeUser,*LePasswd; QPushButton *PbPut,*PbGet; QNetworkAccessManager manager;//这个是重点protected slots: //处理按钮的点击信号 void slotPut(); void slotGet(); //处理网络连接的信号 void managePut(QNetworkReply*); void manageGet(QNetworkReply*);};#endif // DIALOG_H

dialog.cpp

#include "dialog.h"Dialog::Dialog(QWidget *parent) : QDialog(parent){ setWindowTitle("My Ftp"); layout=new QGridLayout(this); LbServer=new QLabel("Server:"); LbUser=new QLabel("User:"); LbPasswd=new QLabel("Passwd:"); LeServer=new QLineEdit("ftp://120.27.41.126/home/myths/1.txt"); LeUser=new QLineEdit("myths"); LePasswd=new QLineEdit("123456"); LePasswd->setEchoMode(QLineEdit::Password);//设置加密显示 PbPut=new QPushButton("Put"); PbGet=new QPushButton("Get"); layout->addWidget(LbServer,0,0); layout->addWidget(LeServer,0,1); layout->addWidget(LbUser,1,0); layout->addWidget(LeUser,1,1); layout->addWidget(LbPasswd,2,0); layout->addWidget(LePasswd,2,1); layout->addWidget(PbPut,3,0); layout->addWidget(PbGet,3,1); setFixedSize(300,200);//固定大小 //按钮点击事件信号槽的连接 connect(PbPut,SIGNAL(clicked()),this,SLOT(slotPut())); connect(PbGet,SIGNAL(clicked()),this,SLOT(slotGet()));}void Dialog::managePut(QNetworkReply * reply){ qDebug()<<reply->error();//输出调试信息 switch(reply->error()){//判断连接后的状态 case QNetworkReply::NoError: QMessageBox::information(this,"Put information","Upload Success!"); break; case QNetworkReply::HostNotFoundError: QMessageBox::information(this,"Put information","Host Not Found!"); break; case QNetworkReply::AuthenticationRequiredError: QMessageBox::information(this,"Put information","Login Failure!"); break; default: QMessageBox::information(this,"Put information","Unknown Failure"); break; }}void Dialog::manageGet(QNetworkReply *reply){ //基本和managerPut类似 qDebug()<<reply->error(); QByteArray data; switch(reply->error()){ case QNetworkReply::NoError: data=reply->readAll();//从url中读取文件内容，输出到data中（也可以再将数据写入到文件中，为了方便，这里就权且打印一下吧） QMessageBox::information(this,"Put information","Upload Success!nThe file you've got is :n"+data); break; case QNetworkReply::HostNotFoundError: QMessageBox::information(this,"Put information","Host Not Found!"); break; case QNetworkReply::AuthenticationRequiredError: QMessageBox::information(this,"Put information","Login Failure!"); break; default: QMessageBox::information(this,"Put information","Unknown Failure"); break; }}Dialog::~Dialog(){}void Dialog::slotPut(){ //判断信息输入完整 if(LeUser->text().isEmpty()||LePasswd->text().isEmpty()||LeServer->text().isEmpty()){ QMessageBox::warning(this,"Error","Please fill in the information"); return ; } //重点！将之前的槽清空并重新连接至需要的 manager.disconnect(SIGNAL(finished(QNetworkReply*))); //完全清空某对象连接的槽可以用manager.disconnect(); connect(&manager,SIGNAL(finished(QNetworkReply*)),SLOT(managePut(QNetworkReply*))); //设置登录信息 QUrl url(LeServer->text()); url.setPort(21); url.setUserName(LeUser->text()); url.setPassword(LePasswd->text()); QByteArray data="This is the test data.n"; /*QNetworkReply *reply=*/ manager.put(QNetworkRequest(url),data);//将data上传到url中，返回的reply将触发网络的连接信号}void Dialog::slotGet(){ //基本意义与slotPut类似 if(LeUser->text().isEmpty()||LePasswd->text().isEmpty()||LeServer->text().isEmpty()){ QMessageBox::warning(this,"Error","Please fill in the information"); return ; } manager.disconnect(SIGNAL(finished(QNetworkReply*))); connect(&manager,SIGNAL(finished(QNetworkReply*)),SLOT(manageGet(QNetworkReply*))); QUrl url(LeServer->text()); url.setPort(21); url.setUserName(LeUser->text()); url.setPassword(LePasswd->text()); /*QNetworkReply *reply=*/ manager.get((QNetworkRequest(url)));}

main.cpp

#include "dialog.h"#include <QApplication>int main(int argc, char *argv[]){ QApplication a(argc, argv); Dialog w; w.show(); return a.exec();}

5、运行截图

权且只显示主界面：

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