柚子快報(bào)邀請(qǐng)碼778899分享：?悟透Qt—Http網(wǎng)絡(luò)編程

http://yzkb.51969.com/

目錄

概述實(shí)踐理論QNetworkAccessManager進(jìn)行Http編程的基本步驟代碼實(shí)戰(zhàn)(重點(diǎn)片段)

概述

網(wǎng)絡(luò)訪問 API 建立在一個(gè) QNetworkAccessManager 對(duì)象之上，該對(duì)象保存了發(fā)送請(qǐng)求所需的公共配置和設(shè)置。它包含代理和緩存配置，以及與此類問題相關(guān)的信號(hào)和可用于監(jiān)視網(wǎng)絡(luò)操作進(jìn)度的回復(fù)信號(hào)。整個(gè) Qt 應(yīng)用程序只需要一個(gè) QNetworkAccessManager 實(shí)例。由于 QNetworkAccessManager 基于 QObject，因此只能從它所屬的線程中使用。

創(chuàng)建了 QNetworkAccessManager 對(duì)象后，應(yīng)用程序可以使用它來通過網(wǎng)絡(luò)發(fā)送請(qǐng)求。提供了一組標(biāo)準(zhǔn)函數(shù)，這些函數(shù)接受請(qǐng)求和可選數(shù)據(jù)，并返回一個(gè) QNetworkReply 對(duì)象。返回的對(duì)象用于獲取響應(yīng)對(duì)應(yīng)請(qǐng)求返回的任何數(shù)據(jù)。

一旦你創(chuàng)建了QNetworkAccessManager對(duì)象，就可以使用它提供的一組標(biāo)準(zhǔn)方法來發(fā)送網(wǎng)絡(luò)請(qǐng)求，而每個(gè)方法都會(huì)返回一個(gè)QNetworkReply對(duì)象，這個(gè)對(duì)象代表了與你發(fā)送的請(qǐng)求相應(yīng)的反饋，通過它，你既可以讀取網(wǎng)絡(luò)應(yīng)答的元數(shù)據(jù)，又可以讀取實(shí)體數(shù)據(jù)。QNetworkAccessManager的get()、post()、head()、put()、deleteResourse()、sendCustomRequest()等方法可用于發(fā)送網(wǎng)絡(luò)請(qǐng)求，http、ftp、https都是小菜一碟，只要你構(gòu)造一個(gè)QNetworkRequest對(duì)象傳遞給它們就行了。

如果你仔細(xì)研究QNetworkAccessManager的接口及其枚舉類型Operation，還有QNetworkRequest的接口及其KnownHeaders、Attribute等枚舉類型，可能會(huì)發(fā)現(xiàn)，其實(shí)，它好像就是專門為http編程設(shè)計(jì)的，畢竟，http協(xié)議在網(wǎng)絡(luò)世界里廣泛使用。不過喜歡ftp的朋友也別灰心，QNetworkAccessManager是萬能的，它也支持下載、上傳等常見的ftp操作。

實(shí)踐理論

我們使用QNetworkAccessManager進(jìn)行網(wǎng)絡(luò)編程，與4個(gè)類打交道比較多一些，這里先介紹一下，為后面的代碼解釋做做準(zhǔn)備。

QNetworkAccessManager是中心，它提供了發(fā)送請(qǐng)求的各種API以及網(wǎng)絡(luò)配置相關(guān)的方法。QNetworkRequest代表一個(gè)網(wǎng)絡(luò)請(qǐng)求，包括URL、HTTP訪問用的UserAgent、用戶名、密碼等都通過它設(shè)置。QNetworkReply是QNetworkAccessManager根據(jù)你提交的QNetworkRequest構(gòu)造的一個(gè)應(yīng)答對(duì)象，一旦請(qǐng)求發(fā)出，你就可以通過它獲知網(wǎng)絡(luò)操作過程中的各種狀態(tài)。QUrl是構(gòu)造請(qǐng)求（QNetworkRequest）時(shí)常用的類，它可以編解碼URL，提取URL中的主機(jī)、路徑、文件、用戶名、密碼等信息。

QNetworkAccessManager進(jìn)行Http編程的基本步驟

根據(jù)URL生成QUrl對(duì)象，然后根據(jù)QUrl創(chuàng)建一個(gè)網(wǎng)絡(luò)請(qǐng)求QNetworkRequest，必要時(shí)可設(shè)置一些header。調(diào)用QNetworkAccessManager的get()、post()等方法中的一個(gè)。使用QNetworkAccessManager返回的QNetworkReply實(shí)例來跟蹤應(yīng)答的各種狀態(tài)反饋。

如果要上傳數(shù)據(jù)到服務(wù)器，則需要提供一個(gè)QIODevice指針或者QByteArray給post()方法。通常情況下你可以使用QFile打開指定的文件然后傳給post()方法來上傳本地文件。而后者則允許你直接將裸數(shù)據(jù)上傳到服務(wù)器。

需要特別說明的是：

開發(fā)者必須自己選擇合適的時(shí)機(jī)釋放QNetworkAccessManager返回的QNetworkReply對(duì)象。請(qǐng)不要在響應(yīng)QNetworkReply對(duì)象的信號(hào)時(shí)直接刪除QNetworkReply對(duì)象，應(yīng)該使用其deleteLater()方法延遲銷毀它。對(duì)于重定向消息，可以通過QNetworkReply::header（QNetworkRequest::LocationHeader）獲取定向到的新地址，然后針對(duì)新地址重走長(zhǎng)征路。

代碼實(shí)戰(zhàn)(重點(diǎn)片段)

首先要在qmake或cmake構(gòu)建中添加相關(guān)配置：

Header: #include CMake: find_package(Qt6 REQUIRED COMPONENTS Network) target_link_libraries(mytarget PRIVATE Qt6::Network) qmake: QT += network

QNetworkAccessManager m_nam;

QNetworkReply * m_reply;

QNetworkRequest * m_request;

QString m_strFilePath;

QFile * m_file;

*************************************************

Widget::Widget(QWidget* parent): QWidget(parent), m_nam(this), m_reply(0), m_request(0), m_file(0) {

setupGUI();

}

Widget::~Widget() {

if (m_file) {

m_file->close();

delete m_file;

}

if (m_reply) {

m_reply->disconnect(this);

m_reply->abort();

delete m_reply;

}

}

static const char* g_ext_to_content_type[] = {

".001", "application/x-001"

, ".301", "application/x-301"

, ".323", "text/h323"

, ".906", "application/x-906"

, ".907", "drawing/907"

, ".a11", "application/x-a11"

, ".acp", "audio/x-mei-aac"

, ".ai", "application/postscript"

, ".aif", "audio/aiff"

, ".aifc", "audio/aiff"

, ".aiff", "audio/aiff"

, ".anv", "application/x-anv"

, ".asa", "text/asa"

, ".asf", "video/x-ms-asf"

, ".asp", "text/asp"

, ".asx", "video/x-ms-asf"

, ".au", "audio/basic"

, ".avi", "video/avi"

, ".awf", "application/vnd.adobe.workflow"

, ".biz", "text/xml"

, ".bmp", "application/x-bmp"

, ".bot", "application/x-bot"

, ".c4t", "application/x-c4t"

, ".c90", "application/x-c90"

, ".cal", "application/x-cals"

, ".cat", "application/vnd.ms-pki.seccat"

, ".cdf", "application/x-netcdf"

, ".cdr", "application/x-cdr"

, ".cel", "application/x-cel"

, ".cer", "application/x-x509-ca-cert"

, ".cg4", "application/x-g4"

, ".cgm", "application/x-cgm"

, ".cit", "application/x-cit"

, ".class", "java/*"

, ".cml", "text/xml"

, ".cmp", "application/x-cmp"

, ".cmx", "application/x-cmx"

, ".cot", "application/x-cot"

, ".conf", "text/plain"

, ".crl", "application/pkix-crl"

, ".crt", "application/x-x509-ca-cert"

, ".csi", "application/x-csi"

, ".css", "text/css"

, ".cut", "application/x-cut"

, ".dbf", "application/x-dbf"

, ".dbm", "application/x-dbm"

, ".dbx", "application/x-dbx"

, ".dcd", "text/xml"

, ".dcx", "application/x-dcx"

, ".der", "application/x-x509-ca-cert"

, ".dgn", "application/x-dgn"

, ".dib", "application/x-dib"

, ".dll", "application/x-msdownload"

, ".doc", "application/msword"

, ".dot", "application/msword"

, ".drw", "application/x-drw"

, ".dtd", "text/xml"

, ".dwf", "Model/vnd.dwf"

, ".dwf", "application/x-dwf"

, ".dwg", "application/x-dwg"

, ".dxb", "application/x-dxb"

, ".dxf", "application/x-dxf"

, ".edn", "application/vnd.adobe.edn"

, ".emf", "application/x-emf"

, ".eml", "message/rfc822"

, ".ent", "text/xml"

, ".epi", "application/x-epi"

, ".eps", "application/x-ps"

, ".eps", "application/postscript"

, ".etd", "application/x-ebx"

, ".exe", "application/x-msdownload"

, ".fax", "image/fax"

, ".fdf", "application/vnd.fdf"

, ".fif", "application/fractals"

, ".fo", "text/xml"

, ".frm", "application/x-frm"

, ".g4", "application/x-g4"

, ".gbr", "application/x-gbr"

, ".gcd", "application/x-gcd"

, ".gif", "image/gif"

, ".gl2", "application/x-gl2"

, ".gp4", "application/x-gp4"

, ".hgl", "application/x-hgl"

, ".hmr", "application/x-hmr"

, ".hpg", "application/x-hpgl"

, ".hpl", "application/x-hpl"

, ".hqx", "application/mac-binhex40"

, ".hrf", "application/x-hrf"

, ".hta", "application/hta"

, ".htc", "text/x-component"

, ".htm", "text/html"

, ".html", "text/html"

, ".htt", "text/webviewhtml"

, ".htx", "text/html"

, ".icb", "application/x-icb"

, ".ico", "image/x-icon"

, ".ico", "application/x-ico"

, ".iff", "application/x-iff"

, ".ig4", "application/x-g4"

, ".igs", "application/x-igs"

, ".iii", "application/x-iphone"

, ".img", "application/x-img"

, ".ini", "text/plain"

, ".ins", "application/x-internet-signup"

, ".isp", "application/x-internet-signup"

, ".IVF", "video/x-ivf"

, ".java", "java/*"

, ".jfif", "image/jpeg"

, ".jpe", "image/jpeg"

, ".jpe", "application/x-jpe"

, ".jpeg", "image/jpeg"

, ".jpg", "image/jpeg"

, ".jpg", "application/x-jpg"

, ".js", "application/x-javascript"

, ".jsp", "text/html"

, ".la1", "audio/x-liquid-file"

, ".lar", "application/x-laplayer-reg"

, ".latex", "application/x-latex"

, ".lavs", "audio/x-liquid-secure"

, ".lbm", "application/x-lbm"

, ".lmsff", "audio/x-la-lms"

, ".log", "text/plain"

, ".ls", "application/x-javascript"

, ".ltr", "application/x-ltr"

, ".m1v", "video/x-mpeg"

, ".m2v", "video/x-mpeg"

, ".m3u", "audio/mpegurl"

, ".m4e", "video/mpeg4"

, ".mac", "application/x-mac"

, ".man", "application/x-troff-man"

, ".math", "text/xml"

, ".mdb", "application/msaccess"

, ".mdb", "application/x-mdb"

, ".mfp", "application/x-shockwave-flash"

, ".mht", "message/rfc822"

, ".mhtml", "message/rfc822"

, ".mi", "application/x-mi"

, ".mid", "audio/mid"

, ".midi", "audio/mid"

, ".mil", "application/x-mil"

, ".mml", "text/xml"

, ".mnd", "audio/x-musicnet-download"

, ".mns", "audio/x-musicnet-stream"

, ".mocha", "application/x-javascript"

, ".movie", "video/x-sgi-movie"

, ".mp1", "audio/mp1"

, ".mp2", "audio/mp2"

, ".mp2v", "video/mpeg"

, ".mp3", "audio/mp3"

, ".mp4", "video/mpeg4"

, ".mpa", "video/x-mpg"

, ".mpd", "application/vnd.ms-project"

, ".mpe", "video/x-mpeg"

, ".mpeg", "video/mpg"

, ".mpg", "video/mpg"

, ".mpga", "audio/rn-mpeg"

, ".mpp", "application/vnd.ms-project"

, ".mps", "video/x-mpeg"

, ".mpt", "application/vnd.ms-project"

, ".mpv", "video/mpg"

, ".mpv2", "video/mpeg"

, ".mpw", "application/vnd.ms-project"

, ".mpx", "application/vnd.ms-project"

, ".mtx", "text/xml"

, ".mxp", "application/x-mmxp"

, ".net", "image/pnetvue"

, ".nrf", "application/x-nrf"

, ".nws", "message/rfc822"

, ".odc", "text/x-ms-odc"

, ".out", "application/x-out"

, ".p10", "application/pkcs10"

, ".p12", "application/x-pkcs12"

, ".p7b", "application/x-pkcs7-certificates"

, ".p7c", "application/pkcs7-mime"

, ".p7m", "application/pkcs7-mime"

, ".p7r", "application/x-pkcs7-certreqresp"

, ".p7s", "application/pkcs7-signature"

, ".pc5", "application/x-pc5"

, ".pci", "application/x-pci"

, ".pcl", "application/x-pcl"

, ".pcx", "application/x-pcx"

, ".pdf", "application/pdf"

, ".pdf", "application/pdf"

, ".pdx", "application/vnd.adobe.pdx"

, ".pfx", "application/x-pkcs12"

, ".pgl", "application/x-pgl"

, ".pic", "application/x-pic"

, ".pko", "application/vnd.ms-pki.pko"

, ".pl", "application/x-perl"

, ".plg", "text/html"

, ".pls", "audio/scpls"

, ".plt", "application/x-plt"

, ".png", "image/png"

, ".png", "application/x-png"

, ".pot", "application/vnd.ms-powerpoint"

, ".ppa", "application/vnd.ms-powerpoint"

, ".ppm", "application/x-ppm"

, ".pps", "application/vnd.ms-powerpoint"

, ".ppt", "application/vnd.ms-powerpoint"

, ".ppt", "application/x-ppt"

, ".pr", "application/x-pr"

, ".prf", "application/pics-rules"

, ".prn", "application/x-prn"

, ".prt", "application/x-prt"

, ".ps", "application/x-ps"

, ".ps", "application/postscript"

, ".ptn", "application/x-ptn"

, ".pwz", "application/vnd.ms-powerpoint"

, ".r3t", "text/vnd.rn-realtext3d"

, ".ra", "audio/vnd.rn-realaudio"

, ".ram", "audio/x-pn-realaudio"

, ".ras", "application/x-ras"

, ".rat", "application/rat-file"

, ".rdf", "text/xml"

, ".rec", "application/vnd.rn-recording"

, ".red", "application/x-red"

, ".rgb", "application/x-rgb"

, ".rjs", "application/vnd.rn-realsystem-rjs"

, ".rjt", "application/vnd.rn-realsystem-rjt"

, ".rlc", "application/x-rlc"

, ".rle", "application/x-rle"

, ".rm", "application/vnd.rn-realmedia"

, ".rmf", "application/vnd.adobe.rmf"

, ".rmi", "audio/mid"

, ".rmj", "application/vnd.rn-realsystem-rmj"

, ".rmm", "audio/x-pn-realaudio"

, ".rmp", "application/vnd.rn-rn_music_package"

, ".rms", "application/vnd.rn-realmedia-secure"

, ".rmvb", "application/vnd.rn-realmedia-vbr"

, ".rmx", "application/vnd.rn-realsystem-rmx"

, ".rnx", "application/vnd.rn-realplayer"

, ".rp", "image/vnd.rn-realpix"

, ".rpm", "audio/x-pn-realaudio-plugin"

, ".rsml", "application/vnd.rn-rsml"

, ".rt", "text/vnd.rn-realtext"

, ".rtf", "application/msword"

, ".rtf", "application/x-rtf"

, ".rv", "video/vnd.rn-realvideo"

, ".sam", "application/x-sam"

, ".sat", "application/x-sat"

, ".sdp", "application/sdp"

, ".sdw", "application/x-sdw"

, ".sit", "application/x-stuffit"

, ".slb", "application/x-slb"

, ".sld", "application/x-sld"

, ".slk", "drawing/x-slk"

, ".smi", "application/smil"

, ".smil", "application/smil"

, ".smk", "application/x-smk"

, ".snd", "audio/basic"

, ".sol", "text/plain"

, ".sor", "text/plain"

, ".spc", "application/x-pkcs7-certificates"

, ".spl", "application/futuresplash"

, ".spp", "text/xml"

, ".ssm", "application/streamingmedia"

, ".sst", "application/vnd.ms-pki.certstore"

, ".stl", "application/vnd.ms-pki.stl"

, ".stm", "text/html"

, ".sty", "application/x-sty"

, ".svg", "text/xml"

, ".swf", "application/x-shockwave-flash"

, ".tdf", "application/x-tdf"

, ".tg4", "application/x-tg4"

, ".tga", "application/x-tga"

, ".tif", "image/tiff"

, ".tif", "application/x-tif"

, ".tiff", "image/tiff"

, ".tld", "text/xml"

, ".top", "drawing/x-top"

, ".torrent", "application/x-bittorrent"

, ".tsd", "text/xml"

, ".txt", "text/plain"

, ".uin", "application/x-icq"

, ".uls", "text/iuls"

, ".vcf", "text/x-vcard"

, ".vda", "application/x-vda"

, ".vdx", "application/vnd.visio"

, ".vml", "text/xml"

, ".vpg", "application/x-vpeg005"

, ".vsd", "application/vnd.visio"

, ".vsd", "application/x-vsd"

, ".vss", "application/vnd.visio"

, ".vst", "application/vnd.visio"

, ".vst", "application/x-vst"

, ".vsw", "application/vnd.visio"

, ".vsx", "application/vnd.visio"

, ".vtx", "application/vnd.visio"

, ".vxml", "text/xml"

, ".wav", "audio/wav"

, ".wax", "audio/x-ms-wax"

, ".wb1", "application/x-wb1"

, ".wb2", "application/x-wb2"

, ".wb3", "application/x-wb3"

, ".wbmp", "image/vnd.wap.wbmp"

, ".wiz", "application/msword"

, ".wk3", "application/x-wk3"

, ".wk4", "application/x-wk4"

, ".wkq", "application/x-wkq"

, ".wks", "application/x-wks"

, ".wm", "video/x-ms-wm"

, ".wma", "audio/x-ms-wma"

, ".wmd", "application/x-ms-wmd"

, ".wmf", "application/x-wmf"

, ".wml", "text/vnd.wap.wml"

, ".wmv", "video/x-ms-wmv"

, ".wmx", "video/x-ms-wmx"

, ".wmz", "application/x-ms-wmz"

, ".wp6", "application/x-wp6"

, ".wpd", "application/x-wpd"

, ".wpg", "application/x-wpg"

, ".wpl", "application/vnd.ms-wpl"

, ".wq1", "application/x-wq1"

, ".wr1", "application/x-wr1"

, ".wri", "application/x-wri"

, ".wrk", "application/x-wrk"

, ".ws", "application/x-ws"

, ".ws2", "application/x-ws"

, ".wsc", "text/scriptlet"

, ".wsdl", "text/xml"

, ".wvx", "video/x-ms-wvx"

, ".xdp", "application/vnd.adobe.xdp"

, ".xdr", "text/xml"

, ".xfd", "application/vnd.adobe.xfd"

, ".xfdf", "application/vnd.adobe.xfdf"

, ".xhtml", "text/html"

, ".xls", "application/vnd.ms-excel"

, ".xls", "application/x-xls"

, ".xlw", "application/x-xlw"

, ".xml", "text/xml"

, ".xpl", "audio/scpls"

, ".xq", "text/xml"

, ".xql", "text/xml"

, ".xquery", "text/xml"

, ".xsd", "text/xml"

, ".xsl", "text/xml"

, ".xslt", "text/xml"

, ".xwd", "application/x-xwd"

, ".x_b", "application/x-x_b"

, ".x_t", "application/x-x_t"

};

static const char* get_content_type(char* filename) {

int i = 0;

int size = sizeof(g_ext_to_content_type) / sizeof(g_ext_to_content_type[0]);

char* ext = filename;

char* slash = strrchr(filename, '/');

if (slash)

slash++;

else

slash = filename;

ext = strrchr(filename, '.');

if (!ext)

return "application/octet-stream";

for (; i < size; i += 2) {

if (!strcmp(ext, g_ext_to_content_type[i]))

return g_ext_to_content_type[i + 1];

}

return "application/octet-stream";

}

QString Widget::requestString(QNetworkRequest* req) {

QString joinedHeader;

QVariant variant = req->header(QNetworkRequest::ContentTypeHeader);

if (variant.isValid()) {

joinedHeader += "content-type: ";

joinedHeader += variant.toString();

joinedHeader += "\n";

}

variant = req->header(QNetworkRequest::UserAgentHeader);

if (variant.isValid()) {

joinedHeader += "user-agent: ";

joinedHeader += variant.toString();

joinedHeader += "\n";

}

QList headerList = req->rawHeaderList();

int count = headerList.size();

QByteArray value;

for (int i = 0; i < count; i++) {

const QByteArray& tag = headerList.at(i);

value = req->rawHeader(tag);

joinedHeader += QString("%1: %2\n").arg(tag.data()).arg(value.data());

}

return joinedHeader;

}

QString Widget::responseString(QNetworkReply* reply) {

QString joinedHeader;

QVariant variant = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);

if (variant.isValid())

joinedHeader = QString("STATUS: %1\n").arg(variant.toInt());

QList headerList = reply->rawHeaderList();

int count = headerList.size();

QByteArray value;

for (int i = 0; i < count; i++) {

const QByteArray& tag = headerList.at(i);

value = reply->rawHeader(tag);

joinedHeader += QString("%1: %2\n").arg(tag.data()).arg(value.data());

}

return joinedHeader;

}

void Widget::onAddHttpHeaderValue() {

if (!m_request)

m_request = new QNetworkRequest();

QString header = m_headerKeyEdit->text();

if (header.compare("user-agent", Qt::CaseInsensitive) == 0)

m_request->setHeader(QNetworkRequest::UserAgentHeader, m_headerValueEdit->text());

m_request->setRawHeader(header, m_headerValueEdit->text());

m_stateText->setText(requestString(m_request));

}

void Widget::onStart() {

if (!m_request)

m_request = new QNetworkRequest();

QString strURL = m_urlEdit->text();

QUrl qurl(strURL);

QString httpMethod = m_methodCombo->currentText();

m_request->setUrl(qurl);

if (httpMethod == "GET") {

QString errorString;

if (!openFile(true, errorString)) {

QMessageBox::warning(this, "Save File Error", errorString, QMessageBox::Ok);

resetState();

return;

}

m_reply = m_nam.get(*m_request);

} else if (httpMethod == "POST") {

QString errorString;

if (!openFile(false, errorString)) {

QMessageBox::warning(this, "Upload File Error", errorString, QMessageBox::Ok);

resetState();

return;

}

m_reply = m_nam.post(*m_request, m_file);

m_request->setHeader(QNetworkRequest::ContentTypeHeader, get_content_type(m_strFilePath.data()));

} else if (httpMethod == "HEAD")

m_reply = m_nam.head(*m_request);

else if (httpMethod == "DELETE")

m_reply = m_nam.deleteResource(*m_request);

else {

QMessageBox::information(this, "information", "Please select a Method!", QMessageBox::Ok);

resetState();

return;

}

connect(m_reply, SIGNAL(finished()), this, SLOT(onFinished()));

connect(m_reply, SIGNAL(readyRead()), this, SLOT(onReadyRead()));

connect(m_reply, SIGNAL(downloadProgress(qint64, qint64)),

this, SLOT(onDownloadProgress(qint64, qint64)));

connect(m_reply, SIGNAL(uploadProgress(qint64, qint64)),

this, SLOT(onUploadProgress(qint64, qint64)));

connect(m_reply, SIGNAL(metaDataChanged()), this, SLOT(onMetaDataChanged()));

connect(m_reply, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(onFinished()));

m_stateText->setText(requestString(m_request));

m_stateText->append("\n===========response==========\n");

}

void Widget::onMetaDataChanged() {

m_stateText->setText(responseString(m_reply));

}

void Widget::onDownloadProgress(qint64 bytesReceived, qint64 bytesTotal) {

if (bytesTotal > 0) {

int value = (bytesReceived * 100) / bytesTotal;

m_progress->setValue(value);

}

}

void Widget::onUploadProgress(qint64 bytesSent, qint64 bytesTotal) {

if (bytesTotal > 0) {

int value = (bytesSent * 100) / bytesTotal;

m_progress->setValue(value);

}

}

void Widget::onReadyRead() {

QByteArray data = m_reply->readAll();

m_stateText->append(QString("read %1 bytes\n").arg(data.length()));

if (m_file) {

m_file->write(data);

}

}

void Widget::onFinished() {

QString strState = m_reply->error() == QNetworkReply::NoError ? "success" : m_reply->errorString();

m_stateText->append(QString("\nhttp request done - %1\n").arg(strState));

m_stateText->append("\n-------\n");

resetState();

}

void Widget::resetState() {

if (m_file) {

m_file->close();

delete m_file;

m_file = 0;

}

if (m_request) {

delete m_request;

m_request = 0;

}

if (m_reply) {

m_reply->disconnect(this);

m_reply->deleteLater();

m_reply = 0;

}

}

函數(shù)——strrchr() const char* strrchr(const char* str, int character); ???????????? char* strrchr(char* str, int character); Locate last occurrence of character in string. Returns a pointer to the last occurrence of character in the C string str. The terminating null-character is considered part of the C string. Therefore, it can also be located to retrieve a pointer to the end of a string. Parameters str - C string. character - Character to be located. It is passed as its int promotion, but it is internally converted back to char. Return Value A pointer to the last occurrence of character in str. If the character is not found, the function returns a null pointer.

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