cpp
复制代码
#include <QCoreApplication>
#include <QVariant>
#include <QDebug>
#include <QDate>
#include <QTime>
#include <QDateTime>
#include <QByteArray>
#include <QStringList>
#include <QColor>
#include <QFont>
#include <QPoint>
#include <QSize>
#include <QRect>
#include <QMetaType>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
// 创建一个QVariant对象并设置其值
QVariant var;
// 1. 整数
int intValue = 42;
var = QVariant(intValue);
// 2. 浮点数
double doubleValue = 3.14159;
var = QVariant(doubleValue);
// 3. 字符串
QString stringValue = "Hello, QVariant!";
var = QVariant(stringValue);
// 4. 布尔值
bool boolValue = true;
var = QVariant(boolValue);
// 5. 列表
QVariantList list;
list.append(1);
list.append("Two");
list.append(3.0);
var = QVariant(list);
// 6. Map
QVariantMap map;
map["name"] = "Alice";
map["age"] = 30;
map["isStudent"] = false;
var = QVariant(map);
// 7. 枚举
enum Color { Red, Green, Blue };
Color colorValue = Blue;
var = QVariant(colorValue);
// 8. 自定义类型
class CustomType {
public:
int value;
QString name;
};
CustomType customValue;
customValue.value = 123;
customValue.name = "Custom";
var = QVariant::fromValue(customValue);
// 9. 数据类型检查
if (var.type() == QVariant::Int) {
int intValue = var.toInt();
}
// 10. 数据类型转换
QString strValue = var.toString();
// 11. 比较
QVariant anotherIntValue = QVariant(42);
if (var == anotherIntValue) {
qDebug() << "var is equal to anotherIntValue";
}
// 12. 访问Map中的值
QVariantMap mapValue = var.toMap();
QString name = mapValue["name"].toString();
int age = mapValue["age"].toInt();
// 13. 获取枚举值名称
QString enumName = var.typeName();
// 14. 清空QVariant
var.clear();
// 15. 判断QVariant是否为空
if (var.isNull()) {
qDebug() << "var is null";
}
// 其他高级方法:
// 16. QVariant类型的自省
QVariant::Type type = var.type();
// 17. QVariant的详细类型信息
const QMetaObject *metaObject = var.metaObject();
// 18. 类型是否可转换
bool canConvert = var.canConvert(QVariant::Int);
// 19. 从字符串创建QVariant
QVariant fromStringVar = QVariant::fromValue("42");
// 20. 将QVariant转为JSON
QJsonObject jsonObject = var.toJsonValue().toObject();
// 21. 将JSON转为QVariant
QVariant fromJsonVar = QVariant::fromValue(jsonObject);
// 22. 根据类型名创建QVariant
QVariant typeVar = QVariant::fromType(QMetaType::Int);
// 23. 使用 QVariantList 创建 QVariant
QVariantList listVar;
listVar << 1 << 2 << 3;
// 24. 使用 QVariantMap 创建 QVariant
QVariantMap mapVar;
mapVar["name"] = "John";
mapVar["age"] = 25;
// 25. QVariant的复制
QVariant copyVar = var;
// 26. 使用 QVariantList 创建 QVariant
QVariantList listVar2 = QVariantList() << 4 << 5 << 6;
// 27. 检查是否有值
if (var.isValid()) {
qDebug() << "var is valid";
}
// 28. 获取 QVariant 内部数据指针
const void *dataPtr = var.constData();
// 29. 获取 QVariant 内部数据大小
int dataSize = var.dataSize();
// 30. 使用自定义转换函数
QVariant customConvertedVar = var.value<CustomType>();
// 31. QDate
QDate dateValue(2023, 11, 4);
var = QVariant(dateValue);
// 32. QTime
QTime timeValue(14, 30);
var = QVariant(timeValue);
// 33. QDateTime
QDateTime dateTimeValue(QDate(2023, 11, 4), QTime(14, 30));
var = QVariant(dateTimeValue);
// 34. QByteArray
QByteArray byteArrayValue = QByteArray("Hello, QVariant!");
var = QVariant(byteArrayValue);
// 35. QStringList
QStringList stringListValue;
stringListValue << "One" << "Two" << "Three";
var = QVariant(stringListValue);
// 36. QColor
QColor colorValue(255, 0, 0); // 红色
var = QVariant(colorValue);
// 37. QFont
QFont fontValue("Arial", 12);
var = QVariant(fontValue);
// 38. QPoint
QPoint pointValue(100, 200);
var = QVariant(pointValue);
// 39. QSize
QSize sizeValue(300, 400);
var = QVariant(sizeValue);
// 40. QRect
QRect rectValue(100, 100, 300, 200);
var = QVariant(rectValue);
// 41. QVariantList,嵌套QVariant
QVariantList nestedList;
nestedList << QVariant(1) << QVariant("Nested") << QVariant(3.0);
QVariant nestedVar = QVariant(nestedList);
var = QVariant(nestedVar);
// 42. QVariantMap,嵌套QVariant
QVariantMap nestedMap;
nestedMap["key1"] = QVariant(42);
nestedMap["key2"] = QVariant("Nested");
QVariant nestedMapVar = QVariant(nestedMap);
var = QVariant(nestedMapVar);
// 43. 多个类型混合的QVariantList
QVariantList mixedList;
mixedList << QVariant(42) << QVariant("Mixed") << QVariant(QDate(2023, 11, 4));
var = QVariant(mixedList);
// 44. 使用toXxx()函数获取值
int intValue = var.toInt();
double doubleValue = var.toDouble();
QString stringValue = var.toString();
QDate date = var.toDate();
QTime time = var.toTime();
QDateTime dateTime = var.toDateTime();
QByteArray byteArray = var.toByteArray();
QStringList stringList = var.toStringList();
QColor color = var.value<QColor>();
QFont font = var.value<QFont>();
QPoint point = var.value<QPoint>();
QSize size = var.value<QSize>();
QRect rect = var.value<QRect>();
// 45. 使用value<T>()函数获取自定义类型
class CustomType {
public:
int value;
QString name;
};
CustomType customValue = var.value<CustomType>();
// 46. 使用constData()获取数据指针
const void *dataPtr = var.constData();
// 47. 检查是否为空
if (var.isNull()) {
qDebug() << "var is null";
}
// 48. 获取类型名称
QString typeName = var.typeName();
// 49. 将QVariant转为JSON字符串
QString jsonStr = QVariant::fromValue(var).toJsonValue().toString();
// 50. 从JSON字符串创建QVariant
QVariant fromJsonVar = QVariant::fromValue(QJsonDocument::fromJson(jsonStr.toUtf8()).toVariant());
// 51. QList
QList<int> intList;
intList << 1 << 2 << 3;
var = QVariant::fromValue(intList);
// 52. QVector
QVector<QString> stringVector;
stringVector << "One" << "Two" << "Three";
var = QVariant::fromValue(stringVector);
// 53. QMap
QMap<QString, int> stringIntMap;
stringIntMap["One"] = 1;
stringIntMap["Two"] = 2;
var = QVariant::fromValue(stringIntMap);
// 54. QStringList
QStringList stringList;
stringList << "Apple" << "Banana" << "Cherry";
var = QVariant::fromValue(stringList);
// 55. QVariantList,混合数据类型
QVariantList mixedDataList;
mixedDataList << 42 << "Mixed" << 3.14;
var = QVariant(mixedDataList);
// 56. QVariantMap,混合数据类型
QVariantMap mixedDataMap;
mixedDataMap["key1"] = 42;
mixedDataMap["key2"] = "Mixed";
mixedDataMap["key3"] = 3.14;
var = QVariant(mixedDataMap);
// 57. QVariantList,深度嵌套
QVariantList deepNestedList;
QVariantList innerList;
innerList << 1 << 2 << 3;
deepNestedList << innerList << "Nested" << 3.14;
var = QVariant(deepNestedList);
// 58. QVariantMap,深度嵌套
QVariantMap deepNestedMap;
QVariantMap innerMap;
innerMap["key1"] = 42;
innerMap["key2"] = "Nested";
deepNestedMap["inner"] = innerMap;
deepNestedMap["key3"] = 3.14;
var = QVariant(deepNestedMap);
// 59. QVariantMap,枚举类型
enum Fruit { Apple, Banana, Cherry };
QVariantMap enumMap;
enumMap["fruit"] = Fruit::Apple;
var = QVariant(enumMap);
// 60. QVariantList,枚举类型
QVariantList enumList;
enumList << Fruit::Apple << Fruit::Banana << Fruit::Cherry;
var = QVariant(enumList);
// 61. QVariantList,指针类型
int* intPointer = new int(42);
var = QVariant::fromValue(intPointer);
// 62. QVariantList,QSharedPointer类型
QSharedPointer<int> sharedInt = QSharedPointer<int>(new int(42));
var = QVariant::fromValue(sharedInt);
// 63. QVariantList,自定义类指针
class CustomType {
public:
int value;
QString name;
};
CustomType* customPointer = new CustomType();
customPointer->value = 42;
customPointer->name = "CustomPointer";
var = QVariant::fromValue(customPointer);
// 64. QVariantList,QList指针
QList<int>* intListPointer = new QList<int>();
intListPointer->append(1);
intListPointer->append(2);
intListPointer->append(3);
var = QVariant::fromValue(intListPointer);
// 65. QVariantList,QMap指针
QMap<QString, int>* stringIntMapPointer = new QMap<QString, int>();
stringIntMapPointer->insert("One", 1);
stringIntMapPointer->insert("Two", 2);
var = QVariant::fromValue(stringIntMapPointer);
// 66. QVariantList,QVariantList指针
QVariantList* nestedListPointer = new QVariantList();
nestedListPointer->append(1);
nestedListPointer->append("Nested");
var = QVariant::fromValue(nestedListPointer);
// 67. QVariantList,QVariantMap指针
QVariantMap* nestedMapPointer = new QVariantMap();
(*nestedMapPointer)["key1"] = 42;
(*nestedMapPointer)["key2"] = "Nested";
var = QVariant::fromValue(nestedMapPointer);
// 68. QVariantList,复合结构
struct ComplexStruct {
int intValue;
QString stringValue;
QMap<QString, QVariant> dataMap;
};
ComplexStruct complexValue = {42, "Complex", stringIntMap};
var = QVariant::fromValue(complexValue);
// 69. QVariantList,QVariant指针
QVariant* varPointer = new QVariant(42);
var = QVariant::fromValue(varPointer);
// 70. QVariantList,QVariantList指针
QVariantList* varListPointer = new QVariantList();
varListPointer->append(1);
varListPointer->append("Nested");
var = QVariant::fromValue(varListPointer);
// 71. QVariantList,QVariantMap指针
QVariantMap* varMapPointer = new QVariantMap();
(*varMapPointer)["key1"] = 42;
(*varMapPointer)["key2"] = "Nested";
var = QVariant::fromValue(varMapPointer);
// 72. 检查是否包含特定类型
if (var.canConvert(QVariant::Int)) {
int convertedInt = var.toInt();
qDebug() << "Can convert to int: " << convertedInt;
}
// 73. 检查是否包含特定自定义类型
bool hasCustomType = QMetaType::type("CustomType") != QMetaType::UnknownType;
if (hasCustomType && var.canConvert(QMetaType::type("CustomType"))) {
CustomType custom = var.value<CustomType>();
qDebug() << "Can convert to CustomType: " << custom.value << custom.name;
}
// 74. 使用 QVariantList 遍历QVariantMap
QVariantMap mapInList;
mapInList["name"] = "John";
mapInList["age"] = 30;
QVariantList listInMap;
listInMap << 1 << 2 << mapInList;
QVariantMap mapWithList;
mapWithList["data"] = listInMap;
var = QVariant(mapWithList);
QVariantList nestedDataList = var.toMap()["data"].toList();
for (const QVariant& item : nestedDataList) {
if (item.canConvert(QVariant::String)) {
QString strValue = item.toString();
qDebug() << "String in nested list: " << strValue;
}
else if (item.canConvert(QVariant::Map)) {
QVariantMap mapValue = item.toMap();
QString name = mapValue["name"].toString();
int age = mapValue["age"].toInt();
qDebug() << "Map in nested list: Name - " << name << ", Age - " << age;
}
}
// 75. 使用 QVariantMap 遍历QVariantMap
QVariantMap mapData;
mapData["key1"] = 42;
mapData["key2"] = "Value";
mapData["key3"] = 3.14;
var = QVariant(mapData);
QVariantMap dataMap = var.toMap();
for (const QString& key : dataMap.keys()) {
QVariant value = dataMap[key];
if (value.canConvert(QVariant::Int)) {
int intValue = value.toInt();
qDebug() << "Key: " << key << " - Int Value: " << intValue;
}
else if (value.canConvert(QVariant::String)) {
QString strValue = value.toString();
qDebug() << "Key: " << key << " - String Value: " << strValue;
}
else if (value.canConvert(QVariant::Double)) {
double doubleValue = value.toDouble();
qDebug() << "Key: " << key << " - Double Value: " << doubleValue;
}
}
// 76. QVariantList 转换为数组
QVariantList listToConvert;
listToConvert << 1 << 2 << 3 << 4 << 5;
int* intArray = listToConvert.data<int>();
for (int i = 0; i < listToConvert.size(); ++i) {
qDebug() << "Array Value: " << intArray[i];
}
// 77. QVariantList 转换为自定义类数组
class CustomType {
public:
int value;
QString name;
};
QVariantList customList;
CustomType custom1 = {1, "One"};
CustomType custom2 = {2, "Two"};
CustomType custom3 = {3, "Three"};
customList << QVariant::fromValue(custom1) << QVariant::fromValue(custom2) << QVariant::fromValue(custom3);
CustomType* customArray = customList.data<CustomType>();
for (int i = 0; i < customList.size(); ++i) {
qDebug() << "Custom Array Value: " << customArray[i].value << customArray[i].name;
}
// 78. 使用 QVariantList 进行排序
QVariantList sortList;
sortList << 5 << 2 << 1 << 4 << 3;
std::sort(sortList.begin(), sortList.end(), [](const QVariant& a, const QVariant& b) {
return a.toInt() < b.toInt();
});
qDebug() << "Sorted List: " << sortList;
// 79. 使用 QVariantList 进行过滤
QVariantList filterList;
filterList << 1 << 2 << 3 << 4 << 5;
QVariantList filtered = filterList.filter([](const QVariant& value) {
return value.toInt() % 2 == 0;
});
qDebug() << "Filtered List: " << filtered;
// 80. 使用 QVariantList 进行映射
QVariantList mapList;
mapList << 1 << 2 << 3;
QVariantList mapped = mapList.map([](const QVariant& value) {
return value.toInt() * 2;
});
qDebug() << "Mapped List: " << mapped;
// 81. 使用 QVariantList 进行折叠
QVariantList foldList;
foldList << 1 << 2 << 3 << 4 << 5;
int sum = foldList.fold(0, [](int accumulator, const QVariant& value) {
return accumulator + value.toInt();
});
qDebug() << "Folded Sum: " << sum;
// 82. 使用 QVariantList 进行查找
QVariantList findList;
findList << 10 << 20 << 30 << 40 << 50;
QVariant found = findList.find([](const QVariant& value) {
return value.toInt() == 30;
});
qDebug() << "Found Value: " << found;
// 83. 使用 QVariantList 进行去重
QVariantList duplicateList;
duplicateList << 1 << 2 << 3 << 2 << 1;
QVariantList unique = duplicateList.unique();
qDebug() << "Unique List: " << unique;
// 84. 使用 QVariantMap 进行排序
QVariantMap sortMap;
sortMap["one"] = 5;
sortMap["two"] = 2;
sortMap["three"] = 1;
QVariantMap sortedMap = sortMap.sortedKeys();
qDebug() << "Sorted Map: " << sortedMap;
// 85. 使用 QVariantMap 进行过滤
QVariantMap filterMap;
filterMap["one"] = 1;
filterMap["two"] = 2;
filterMap["three"] = 3;
QVariantMap filteredMap = filterMap.filter([](const QVariant& key, const QVariant& value) {
return value.toInt() % 2 == 0;
});
qDebug() << "Filtered Map: " << filteredMap;
// 86. 使用 QVariantMap 进行映射
QVariantMap mapMap;
mapMap["one"] = 1;
mapMap["two"] = 2;
mapMap["three"] = 3;
QVariantMap mappedMap = mapMap.map([](const QVariant& key, const QVariant& value) {
return QVariant(key.toString() + "Squared", value.toInt() * value.toInt());
});
qDebug() << "Mapped Map: " << mappedMap;
// 87. 使用 QVariantMap 进行折叠
QVariantMap foldMap;
foldMap["one"] = 1;
foldMap["two"] = 2;
foldMap["three"] = 3;
int sumMap = foldMap.fold(0, [](int accumulator, const QVariant& key, const QVariant& value) {
return accumulator + value.toInt();
});
qDebug() << "Folded Sum in Map: " << sumMap;
return a.exec();
}