Question

如何将GeoJson文件的所有字符串转换为类对象？

GeoJson文件示例：

{"type":"FeatureCollection","features" :[ 
{"type":"feature","properties":{"type":"126"},"geometry":
{"type":"POINT","coordinates":[197,98]}}
{"type":"feature","properties":{"type":"126"},"geometry":
{"type":"POINT","coordinates":[142,24]}}
{"type":"feature","properties":{"type":"126"},"geometry":
{"type":"POINT","coordinates":[185,53]}}]}

我需要为每个字符串创建一个类对象并填写其字段：

class Json
{
public:
    Json();
    QString type;
    QString propeties_type;
    QString geometry_type;
    int x_coord,y_coord;
};

我尝试使用QVariant，但我不知道如何提取信息：

QByteArray data = file.readAll();
QJsonDocument jsdoc = QJsonDocument::fromJson(data);
QVariant variant = jsdoc.object()["features"].toVariant();

Answer 1

我会按以下方式进行：

std::vector<Json> result;

QByteArray data = file.readAll();
QJsonDocument jsdoc = QJsonDocument::fromJson(data);

QJsonArray features = jsdoc.object()["features"].toArray();

QJsonArray::const_iterator it = features.constBegin();
while (it != features.constEnd())
{
  Json json;

  QJsonObject feature = it->toObject();

  json.type = "feature";
  json.propeties_type = feature["properties"].toObject()["type"].toString();

  QJsonObject geometry = feature["geometry"].toObject();
  json.geometry_type = geometry["type"].toString();

  QJsonArray coordinates = geometry["coordinates"].toArray();
  assert(coordinates.size() == 2);
  json.x_coord = coordinates.at(0).toInt();
  json.x_coord = coordinates.at(1).toInt();

  result.push_back(json);

  ++it;
}

代码生成Json个对象的向量，每个对象都包含有关“特征”的信息。

如何从GeoJson文件中提取数据到Qt类对象？

1 个答案: