如何用Qt库编写FTP上传下载功能的示例代码？

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Qt的Network模块提供了丰富的网络编程功能。该模块包含多种类，例如QNetworkAccessManager、QNetworkReply等，用于实现网络通信。以下是用Qt实现FTP上传和下载的简单示例，供大家参考：

cpp#include #include #include #include #include

class FtpClient : public QObject { Q_OBJECT

public: FtpClient(QObject *parent=nullptr) : QObject(parent) { QNetworkAccessManager *manager=new QNetworkAccessManager(this); connect(manager, &QNetworkAccessManager::finished, this, &FtpClient::onRequestFinished); }

public slots: void uploadFile(const QString &filePath, const QString &ftpPath) { QFile file(filePath); if (!file.open(QIODevice::ReadOnly)) { qWarning(Unable to open file for reading: %s, filePath.toUtf8().constData()); return; }

QNetworkRequest request(QUrl(ftp://username:password@ftpserver.com/ + ftpPath)); QNetworkReply *reply=manager->put(request, &file);

file.close(); }

void downloadFile(const QString &ftpPath, const QString &localPath) { QNetworkRequest request(QUrl(ftp://username:password@ftpserver.com/ + ftpPath)); QNetworkReply *reply=manager->get(request);

QFile file(localPath); if (!file.open(QIODevice::WriteOnly)) { qWarning(Unable to open file for writing: %s, localPath.toUtf8().constData()); return; }

connect(reply, &QNetworkReply::finished, [this, &file, reply]() { file.write(reply->readAll()); file.close(); reply->deleteLater(); }); }

private slots: void onRequestFinished(QNetworkReply *reply) { if (reply->error()) { qWarning(Error: %s, reply->errorString().toUtf8().constData()); } else { qDebug(Success); } reply->deleteLater(); }};

int main(int argc, char *argv[]) { QCoreApplication a(argc, argv);

FtpClient client; client.uploadFile(local_file.txt, remote_file.txt); client.downloadFile(remote_file.txt, local_file.txt);

return a.exec();}

以上代码展示了如何使用Qt的Network模块实现FTP客户端的上传和下载功能。你可以根据实际需求调整代码中的参数和逻辑。

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 gui QT += network #这里要添加这个库 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets TARGET = QFtp TEMPLATE = app SOURCES += main.cpp dialog.cpp HEADERS += 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_OBJECT public: 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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