利用rapidjson实现解析嵌套的json的方法示例

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利用rapidjson解析嵌套的json

看json串1：{"system":{"version":"v2.6.1", "name":"value"}}

废话少说，直接撸代码：

#include <iostream>
#include <stdio.h>
#include<unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<sstream>
// 请自己下载开源的rapidjson
#include "rapidjson/prettywriter.h"
#include "rapidjson/rapidjson.h"
#include "rapidjson/document.h"
#include "rapidjson/stringbuffer.h"
#include "rapidjson/writer.h"
#include "rapidjson/memorystream.h"
using namespace std;
using rapidjson::Document;
using rapidjson::StringBuffer;
using rapidjson::Writer;
using namespace rapidjson;
string getVersion(const string &jvStr)
{
 Document document;
 if (document.Parse(jvStr.c_str()).HasParseError() || !document.HasMember("system")) 
 {
 return "";
 }
 const rapidjson::Value &jvObject = document["system"];
 if(!jvObject.IsObject())
 {
 return "";
 }
 if(!jvObject.HasMember("version"))
 {
 return "";
 }
 const rapidjson::Value &jv = jvObject["version"];
 return jv.GetString();
}
int main(int argc, char *argv[])
{
 string s = "{\"system\":{\"version\":\"v2.6.1\", \"name\":\"value\"}}";
 cout << s << endl;
 cout << getVersion(s) << endl;
 return 0;
}

结果：

{"system":{"version":"v2.6.1", "name":"value"}}
v2.6.1

再看字符串：{"system": "{\"version\":\"v2.6.1\", \"name\":\"value\"}"}

直接上马：

#include <iostream>
#include <stdio.h>
#include<unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<sstream>
// 请自己下载开源的rapidjson
#include "rapidjson/prettywriter.h"
#include "rapidjson/rapidjson.h"
#include "rapidjson/document.h"
#include "rapidjson/stringbuffer.h"
#include "rapidjson/writer.h"
#include "rapidjson/memorystream.h"
using namespace std;
using rapidjson::Document;
using rapidjson::StringBuffer;
using rapidjson::Writer;
using namespace rapidjson;
string getStringFromJson(const string &jsStr, const string &strKey) 
{ 
  Document document; 
  if (document.Parse(jsStr.c_str()).HasParseError() || !document.HasMember(strKey.c_str()))  
  { 
    return ""; 
  } 
  const rapidjson::Value &jv = document[strKey.c_str()]; 
  return jv.GetString(); 
} 
int main(int argc, char *argv[])
{
 string s = "{\"system\": \"{\\\"version\\\":\\\"v2.6.1\\\", \\\"name\\\":\\\"value\\\"}\"}";
 cout << s << endl;
 string str = getStringFromJson(s, "system");
 cout << str << endl;
 cout << getStringFromJson(str, "version") << endl;
 return 0;
}

结果：