C++ 利用RapidJSON解析和构造json字符串

[Shellbye]

RapidJSON是一款由腾讯开源的json处理包，我在项目中使用的时候，还有点不太熟悉，所以简单记录一些东西。

#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"

using namespace rapidjson;

int main() {

    // official example to parse json
    const char* json = "{\"project\":\"rapidjson\",\"stars\":10}";
    Document d;
    d.Parse(json);
    // 2. 利用 DOM 作出修改。
    Value& s = d["stars"];
    s.SetInt(s.GetInt() + 1);
    // 3. 把 DOM 转换（stringify）成 JSON。
    StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    d.Accept(writer);
    // Output {"project":"rapidjson","stars":11}
    std::cout << buffer.GetString() << std::endl;


    // Build json string
    Document jsondoc;
    jsondoc.SetObject();
    Document::AllocatorType& allocator = jsondoc.GetAllocator();
    Value s2;
    s2 = "This is value";
    jsondoc.AddMember("key2", s2, allocator);
    StringBuffer buffer2;
    Writer<StringBuffer> writer2(buffer2);
    jsondoc.Accept(writer2);
    std::cout << buffer2.GetString() << std::endl;

    // Build json use already exists string
    Document jsondoc3;
    jsondoc3.SetObject();
    std::string a = "A old string";
    Document::AllocatorType& allocator3 = jsondoc3.GetAllocator();
    Value s3;
    s3.SetString(StringRef(a.c_str())); // This is the special place
    jsondoc3.AddMember("test", s3, allocator3);
    StringBuffer buffer3;
    Writer<StringBuffer> writer3(buffer3);
    jsondoc3.Accept(writer3);
    std::cout << buffer3.GetString() << std::endl;

    return 0;
}

The output is,

{"project":"rapidjson","stars":11}
{"key2":"This is value"}
{"test":"A old string"}