C++ 如何将 RapidJSON 文档序列化为字符串？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/33294941/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How to serialize RapidJSON document to a string?
提问by Lochana Thenuwara
How to serialize RapidJSON document to a string?
In all the examples the serializing text is redirected to the standard output through the FileStream, but I need to redirect it to a string variable.
如何将 RapidJSON 文档序列化为字符串？
在所有示例中，序列化文本都通过 重定向到标准输出FileStream，但我需要将其重定向到字符串变量。
回答by A.Franzen
Like this:
像这样：
const char *GetJsonText()
{
rapidjson::StringBuffer buffer;
buffer.Clear();
rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
doc.Accept(writer);
return strdup( buffer.GetString() );
}
Then of couse you have to call free() on the return, or do:
然后当然你必须在返回时调用 free() ，或者执行以下操作：
return string( buffer.GetString() );
instead.
反而。
回答by Milo Yip
In the first page of the project, the code already shows how to serialize a document into a string (stringify a document):
在项目的第一页，代码已经展示了如何将文档序列化为字符串（stringify a document）：
// 3. Stringify the DOM
StringBuffer buffer;
Writer<StringBuffer> writer(buffer);
d.Accept(writer);
// Output {"project":"rapidjson","stars":11}
std::cout << buffer.GetString() << std::endl;
buffer.GetString()here returns a string of const char*type. It also has a buffer.GetSize()for returning the size of output string. So, if you would convert it to a std::string, the best way is:
buffer.GetString()这里返回一个const char*类型的字符串。它还有一个buffer.GetSize()用于返回输出字符串的大小。因此，如果您要将其转换为 a std::string，最好的方法是：
std::string s(buffer.GetString(), buffer.GetSize());
The tutorial.cppalso show the same thing, in addition to other common usage of RapidJSON.
该tutorial.cpp也显示了同样的事情，除了RapidJSON的其他常见的用法。
回答by Lochana Thenuwara
Example code:
示例代码：
Document document;
const char *json = " { \"x\" : \"0.01\", \"y\" :\"0.02\" , \"z\" : \"0.03\"} ";
document.Parse<0>(json);
//convert document to string
StringBuffer strbuf;
strbuf.Clear();
Writer<StringBuffer> writer(strbuf);
document.Accept(writer);
std::string ownShipRadarString = strbuf.GetString();
std::cout << "**********************************************" << ownShipRadarString << std::endl;
回答by Simon Pickup
To avoid having to copy out the string contents, you can create a rapidjson Stream-concept class to wrap an existing std::string, ref: https://github.com/Tencent/rapidjson/issues/846#issuecomment-298088278
为避免复制字符串内容，您可以创建一个 Rapidjson Stream-concept 类来包装现有的 std::string，参考：https: //github.com/Tencent/rapidjson/issues/846#issuecomment-298088278
In fact, not all the methods implemented there are required. This should do:
事实上，并非所有在那里实现的方法都是必需的。这应该做：
void writeDocumentToString(const rapidjson::Document& document,
std::string& output)
{
class StringHolder
{
public:
typedef char Ch;
StringHolder(std::string& s) : s_(s) { s_.reserve(4096); }
void Put(char c) { s_.push_back(c); }
void Flush() { return; }
private:
std::string& s_;
};
StringHolder os(output);
rapidjson::Writer<StringHolder> writer(os);
document.Accept(writer);
}
