Qt学习笔记网络(一)-白红宇

Qt学习笔记网络(一)

阅读量：5052 次

发布时间：2019-06-12

本文共 5252 字，大约阅读时间需要 17 分钟。

Qt5 移除了QHttp是因为功能重复用QNetworkAccessManager完全能搞定

新建一个控制台应用程序

看一下QNetworkAccessManager的帮助文档

需要添加Qt + =network

新建一个类

.h文件

#ifndef DOWNPAGES_H#define DOWNPAGES_H#include
     
      #include 
      
       class DownPages : public QObject{    Q_OBJECTpublic:    explicit DownPages(QObject *parent = 0);    void Do_Download();signals:public slots:void replyFinished(QNetworkReply*);private :    QNetworkAccessManager *manager;};#endif // DOWNPAGES_H

我们声明了一个 QNetworkAccesManager

在.cpp里我们把它初始化并把它的finshed信号关联槽

并判断状态是如果是200也就是请求正常状态把页面输出

.cpp文件

#include "downpages.h"#include 
     
      #include
      
       #include
       
        #include
        
         DownPages::DownPages(QObject *parent) :    QObject(parent){    manager = new QNetworkAccessManager(this);    connect(manager, SIGNAL(finished(QNetworkReply*)),            this, SLOT(replyFinished(QNetworkReply*)));    QUrl url;    //url.setUrl("http://www.cnblogs.com/a/b");    //url.setUrl("http://www.baidu.com/");    url.setUrl("http://www.sibaieteco.com/");    //url.setUrl("www.abaibduc.com");    QNetworkRequest request(url);    manager->get(request);}void DownPages::Do_Download(){}/* * 请求完成 * * */void DownPages::replyFinished(QNetworkReply * reply){    //查看是否有错误    switch(reply->error())    {    //如果没有错误把页面输出    case QNetworkReply::NoError:        qDebug()<<"no error";    {        QTextCodec * cod=QTextCodec::codecForName("utf-8");        QString str=cod->toUnicode(reply->readAll());        qDebug()<
         
          request().url();        int httpStatus = reply->attribute(                    QNetworkRequest::HttpStatusCodeAttribute).toInt();        QString reason = reply->attribute( QNetworkRequest::HttpReasonPhraseAttribute ).toString();        qDebug()<<"url"<
          
           <
           
            <<" "<
            
             errorString()<<" error "<
             
              error(); } } qDebug()<<"finished";}

再在这个基础上添加一个下载功能

.h文件

#ifndef DOWNPAGES_H#define DOWNPAGES_H#include
     
      #include 
      
       #include 
       
        class QNetworkReply;class DownPages : public QObject{    Q_OBJECTpublic:    explicit DownPages(QObject *parent = 0);    void Do_Download();signals:public slots:void replyFinished(QNetworkReply*);void readyRead();void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);void downFinished();private :    QNetworkAccessManager *manager;    QNetworkReply * managerReply;    QFile *file;};#endif // DOWNPAGES_H

.cpp文件

主要是添加了这三个信号

managerReply  = manager->get(request);    connect(managerReply,SIGNAL(readyRead()),this,SLOT(readyRead()));    connect(managerReply,SIGNAL(downloadProgress(qint64,qint64)),            this,SLOT(downloadProgress(qint64,qint64)));    connect(managerReply,SIGNAL(finished()),this,SLOT(downFinished()));

readyRead()开始下载数据

DownloadProgress显示下载的进度

还有一个finished

#include "downpages.h"#include 
     
      #include
      
       #include
       
        #include
        
         #include
         
          #include
          
           DownPages::DownPages(QObject *parent) : QObject(parent){ manager = new QNetworkAccessManager(this); connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*))); QUrl url; //url.setUrl("http://www.cnblogs.com/a/b"); //url.setUrl("http://www.baidu.com/"); //url.setUrl("http://www.sibaieteco.com/"); url.setUrl("http://files.cnblogs.com/li-peng/WPFMultLanguageDemo.rar"); QNetworkRequest request(url); managerReply = manager->get(request); connect(managerReply,SIGNAL(readyRead()),this,SLOT(readyRead())); connect(managerReply,SIGNAL(downloadProgress(qint64,qint64)), this,SLOT(downloadProgress(qint64,qint64))); connect(managerReply,SIGNAL(finished()),this,SLOT(downFinished()));}void DownPages::Do_Download(){}void DownPages::replyFinished(QNetworkReply * reply){ switch(reply->error()) { case QNetworkReply::NoError: qDebug()<<"no error"; { QTextCodec * cod=QTextCodec::codecForName("utf-8"); QString str=cod->toUnicode(reply->readAll()); //qDebug()<
           
            request().url(); int httpStatus = reply->attribute( QNetworkRequest::HttpStatusCodeAttribute).toInt(); QString reason = reply->attribute( QNetworkRequest::HttpReasonPhraseAttribute ).toString(); qDebug()<<"url"<
            
             <
             
              <<" "<
              
               errorString()<<" error "<
               
                error(); } } qDebug()<<"finished";}void DownPages::readyRead(){ QFileInfo fileinfo(managerReply->url().path()); QString thefileName = fileinfo.fileName().isEmpty()?"index.html":fileinfo.fileName(); QString thePath ="E:/Test/Down/"; //qDebug()<
                
                 open(QIODevice::Append))// {// file->write(managerReply->readAll());// file->flush();// file->close();// } if(file->open(QIODevice::Append )) { file->write(managerReply->readAll()); qDebug()<<"flu"; file->flush(); } //delete file;}void DownPages::downloadProgress(qint64 bytesReceived, qint64 bytesTotal){ qDebug()<<"Total: "<
                 
                  <<" current received : "<
                  
                   flush(); file->close(); delete file;}

file->open(QIODevice::Append)

枚举值	描述
`QIODevice::NotOpen`	未打开
`QIODevice::ReadOnly`	以只读方式打开
`QIODevice::WriteOnly`	以只写方式打开
`QIODevice::ReadWrite`	以读写方式打开
`QIODevice::Append`	以追加的方式打开，新增加的内容将被追加到文件末尾
`QIODevice::Truncate`	以重写的方式打开，在写入新的数据时会将原有数据全部清除，游标设置在文件开头。
`QIODevice::Text`	在读取时，将行结束符转换成 \n；在写入时，将行结束符转换成本地格式，例如 Win32 平台上是 \r\n
`QIODevice::Unbuffered`	忽略缓存