C++ 使用 Qt 进行序列化
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原文地址: http://stackoverflow.com/questions/2570679/
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Serialization with Qt
提问by Narek
I am programming a GUI with Qt library. In my GUI I have a huge std::map.
我正在用 Qt 库编程一个 GUI。在我的 GUI 中，我有一个巨大的 std::map。
"MyType" is a class that has different kinds of fields.
“MyType”是一个具有不同类型字段的类。
I want to serialize the std::map. How can I do that? Does Qt provides us with neccesary features?
我想序列化 std::map。我怎样才能做到这一点？Qt 是否为我们提供了必要的功能？
回答by Narek
QDataStream handles a variety of C++ and Qt data types. The complete list is available at http://doc.qt.io/qt-4.8/datastreamformat.html. We can also add support for our own custom types by overloading the << and >> operators. Here's the definition of a custom data type that can be used with QDataStream:
QDataStream 处理各种 C++ 和 Qt 数据类型。完整列表可在http://doc.qt.io/qt-4.8/datastreamformat.html 获得。我们还可以通过重载 << 和 >> 运算符来添加对我们自己的自定义类型的支持。这是可以与 QDataStream 一起使用的自定义数据类型的定义：
class Painting
{
public:
Painting() { myYear = 0; }
Painting(const QString &title, const QString &artist, int year) {
myTitle = title;
myArtist = artist;
myYear = year;
}
void setTitle(const QString &title) { myTitle = title; }
QString title() const { return myTitle; }
...
private:
QString myTitle;
QString myArtist;
int myYear;
};
QDataStream &operator<<(QDataStream &out, const Painting &painting);
QDataStream &operator>>(QDataStream &in, Painting &painting);
Here's how we would implement the << operator:
下面是我们如何实现 << 操作符：
QDataStream &operator<<(QDataStream &out, const Painting &painting)
{
out << painting.title() << painting.artist()
<< quint32(painting.year());
return out;
}
To output a Painting, we simply output two QStrings and a quint32. At the end of the function, we return the stream. This is a common C++ idiom that allows us to use a chain of << operators with an output stream. For example:
为了输出一幅画，我们只需输出两个 QStrings 和一个 quint32。在函数结束时，我们返回流。这是一个常见的 C++ 习惯用法，它允许我们在输出流中使用一连串 << 运算符。例如：
out << painting1 << painting2 << painting3;
出<<绘画1<<绘画2<<绘画3；
The implementation of operator>>() is similar to that of operator<<():
operator>>() 的实现与 operator<<() 类似：
QDataStream &operator>>(QDataStream &in, Painting &painting)
{
QString title;
QString artist;
quint32 year;
in >> title >> artist >> year;
painting = Painting(title, artist, year);
return in;
}
This is from: C++ GUI Programming with Qt 4 By Jasmin Blanchette, Mark Summerfield
这是来自：C++ GUI Programming with Qt 4 By Jasmin Blanchette, Mark Summerfield
