利用rapidjson解析嵌套的json

来源：互联网发布：杨修之死知乎编辑：程序博客网时间：2024/04/29 21:29

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：

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

第二种方式的json串，看起来太恶心了。

另外，再次强调一下， json串解析的时候，容易core dump, 所以要做好异常判断，也要注意类型。

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