Describes how to export data in VCard format.
This part covers some additional features that make the address book more convenient for the frequent user.
Although our address book is useful in isolation, it would be better if we could exchange contact data with other applications. The vCard format is a popular file format that can be used for this purpose. Here we extend our address book client to allow contacts to be exported to vCard
.vcf
文件。
我们添加
QPushButton
对象，
exportButton
, and a corresponding public slot,
exportAsVCard()
to our
AddressBook
类在
addressbook.h
文件。
void exportAsVCard();
...
QPushButton *exportButton;
在
AddressBook
constructor, we connect
exportButton
's
clicked()
signal to
exportAsVCard()
. We also add this button to our
buttonLayout1
, the layout responsible for our panel of buttons on the right.
In our
exportAsVCard()
function, we start by extracting the contact's name into
名称
. We declare
firstName
,
lastName
and
nameList
. Next, we look for the index of the first white space in
名称
. If there is a white space, we split the contact's name into
firstName
and
lastName
. Then, we replace the space with an underscore ("
_
"). Alternately, if there is no white space, we assume that the contact only has a first name.
void AddressBook::exportAsVCard() { QString name = nameLine->text(); QString address = addressText->toPlainText(); QString firstName; QString lastName; QStringList nameList; int index = name.indexOf(" "); if (index != -1) { nameList = name.split(QRegularExpression("\\s+"), Qt::SkipEmptyParts); firstName = nameList.first(); lastName = nameList.last(); } else { firstName = name; lastName = ""; } QString fileName = QFileDialog::getSaveFileName(this, tr("Export Contact"), "", tr("vCard Files (*.vcf);;All Files (*)")); if (fileName.isEmpty()) return; QFile file(fileName);
就像
saveToFile()
function, we open a file dialog to let the user choose a location for the file. Using the file name chosen, we create an instance of
QFile
to write to.
We attempt to open the file in
WriteOnly
mode. If this process fails, we display a
QMessageBox
to inform the user about the problem and return. Otherwise, we pass the file as a parameter to a
QTextStream
对象，
out
。像
QDataStream
，
QTextStream
class provides functionality to read and write plain text to files. As a result, the
.vcf
file generated can be opened for editing in a text editor.
if (!file.open(QIODevice::WriteOnly)) {
QMessageBox::information(this, tr("Unable to open file"),
file.errorString());
return;
}
QTextStream out(&file);
We then write out a vCard file with the
BEGIN:VCARD
tag, followed by the
VERSION:2.1
tag. The contact's name is written with the
N:
tag. For the
FN:
tag, which fills in the "File as" property of a vCard, we have to check whether the contact has a last name or not. If the contact does, we use the details in
nameList
to fill it. Otherwise, we write
firstName
仅。
out << "BEGIN:VCARD" << '\n';
out << "VERSION:2.1" << '\n';
out << "N:" << lastName << ';' << firstName << '\n';
if (!nameList.isEmpty())
out << "FN:" << nameList.join(' ') << '\n';
else
out << "FN:" << firstName << '\n';
We proceed to write the contact's address. The semicolons in the address are escaped with "\", the newlines are replaced with semicolons, and the commas are replaced with spaces. Lastly, we write the
ADR;HOME:;
tag, followed by
address
and then the
END:VCARD
标签。
address.replace(";", "\\;", Qt::CaseInsensitive);
address.replace('\n', ";", Qt::CaseInsensitive);
address.replace(",", " ", Qt::CaseInsensitive);
out << "ADR;HOME:;" << address << '\n';
out << "END:VCARD" << '\n';
QMessageBox::information(this, tr("Export Successful"),
tr("\"%1\" has been exported as a vCard.").arg(name));
}
In the end, a QMessageBox is displayed to inform the user that the vCard has been successfully exported.
vCard is a trademark of the Internet Mail Consortium .