如何在Qt5中创建/读/写JSon文件 [英] How to create/read/write JSon files in Qt5

问题描述

Qt5有一个新的JSon解析器，我想使用它。问题是，它不是太清楚什么功能做外行人的术语，如何写它的代码。

我想知道在Qt5中创建Json文件的代码，以及封装是什么意思。

解决方案

示例从文件读取json

 code> / * test.json * / 
 {
appDesc：{
description：SomeDescription，
message：SomeMessage
}，
appName：{
description：Home，
message：Welcome，
imp：[awesome ，best，good] 
} 
} 
 
 
 void readJson（）
 {
 QString val; 
 QFile文件; 
 file.setFileName（test.json）; 
 file.open（QIODevice :: ReadOnly | QIODevice :: Text）; 
 val = file.readAll（）; 
 file.close（）; 
 qWarning（）<< val; 
 QJsonDocument d = QJsonDocument :: fromJson（val.toUtf8（））; 
 QJsonObject sett2 = d.object（）; 
 QJsonValue value = sett2.value（QString（appName））; 
 qWarning（）<<值; 
 QJsonObject item = value.toObject（）; 
 qWarning（）<< tr（QJsonObject of description：）<<项目; 
 
 / *包含字符串值获取值并转换为字符串* / 
 qWarning（）< tr（QJsonObject [appName] of description：）<<商品描述]; 
 QJsonValue subobj = item [description]; 
 qWarning（）<< subobj.toString（）; 
 
 / * incase数组get数组并转换成字符串* / 
 qWarning（）<< tr（QJsonObject [appName] of value：）< item [imp]; 
 QJsonArray test = item [imp]。toArray（）; 
 qWarning（）<< test [1] .toString（）; 
} 
  

---

OUTPUT

  QJsonValue（object，QJsonObject（{description：Home，imp：[awesome ，best，good]，message：YouTube}））
QJsonObject of description：QJsonObject（{description：Home，imp：[awesome， best，good]，message：YouTube}）
QJsonObject [appName] of description：QJsonValue（string，Home）
Home
 QJsonObject [appName] value：QJsonValue（array，QJsonArray（[awesome，best，good]））
best
  pre> 
 
 
 
 
 
 示例从字符串读取json。 ** 
 ** 将json分配给下面的字符串，并使用上面的readJson（）函数  
  val = 
'{
appDesc：{
description：SomeDescription，
message：SomeMessage
 }，
appName：{
description：Home，
message：Welcome，
imp：[awesome，best ，good] 
} 
}'; 
 
 
 
 
 
 
 
 
  OUTPUT  p> 
 
 
  QJsonValue（object，QJsonObject（{description：Home，imp：[awesome，best good]，message：YouTube}））
QJsonObject of description：QJsonObject（{description：Home，imp：[awesome，best好的]，消息：YouTube}）
QJsonObject [appName]的描述：QJsonValue（string，Home）
Home
的值：QJsonValue（array，QJsonArray（[awesome，best，good]））
best
  
Qt5 has a new JSon parser and I want to use it.  The problem is that it isn't too clear about what the functions do in layman's terms and how to write code with it.  That or I could be reading it wrong.

I want to know the code on creating a Json file in Qt5 and what "encapsulates" mean.
解决方案
Example read json from file
/* test.json */
{
   "appDesc": {
      "description": "SomeDescription",
      "message": "SomeMessage"
   },
   "appName": {
      "description": "Home",
      "message": "Welcome",
      "imp":["awesome","best","good"]
   }
}


void readJson()
   {
      QString val;
      QFile file;
      file.setFileName("test.json");
      file.open(QIODevice::ReadOnly | QIODevice::Text);
      val = file.readAll();
      file.close();
      qWarning() << val;
      QJsonDocument d = QJsonDocument::fromJson(val.toUtf8());
      QJsonObject sett2 = d.object();
      QJsonValue value = sett2.value(QString("appName"));
      qWarning() << value;
      QJsonObject item = value.toObject();
      qWarning() << tr("QJsonObject of description: ") << item;

      /* incase of string value get value and convert into string*/
      qWarning() << tr("QJsonObject[appName] of description: ") << item["description"];
      QJsonValue subobj = item["description"];
      qWarning() << subobj.toString();

      /* incase of array get array and convert into string*/
      qWarning() << tr("QJsonObject[appName] of value: ") << item["imp"];
      QJsonArray test = item["imp"].toArray();
      qWarning() << test[1].toString();
   }




OUTPUT
QJsonValue(object, QJsonObject({"description": "Home","imp": ["awesome","best","good"],"message": "YouTube"}) ) 
"QJsonObject of description: " QJsonObject({"description": "Home","imp": ["awesome","best","good"],"message": "YouTube"}) 
"QJsonObject[appName] of description: " QJsonValue(string, "Home") 
"Home" 
"QJsonObject[appName] of value: " QJsonValue(array, QJsonArray(["awesome","best","good"]) ) 
"best" 




Example read json from string. **
**assign json to string as below and use above readJson() function
val =   
'  {
       "appDesc": {
          "description": "SomeDescription",
          "message": "SomeMessage"
       },
       "appName": {
          "description": "Home",
          "message": "Welcome",
          "imp":["awesome","best","good"]
       }
    }';




OUTPUT
QJsonValue(object, QJsonObject({"description": "Home","imp": ["awesome","best","good"],"message": "YouTube"}) ) 
"QJsonObject of description: " QJsonObject({"description": "Home","imp": ["awesome","best","good"],"message": "YouTube"}) 
"QJsonObject[appName] of description: " QJsonValue(string, "Home") 
"Home" 
"QJsonObject[appName] of value: " QJsonValue(array, QJsonArray(["awesome","best","good"]) ) 
"best" 


                        
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