1.下载
GitHub - Tencent/rapidjson: A fast JSON parser/generator for C++ with both SAX/DOM style APIA fast JSON parser/generator for C++ with both SAX/DOM style API - Tencent/rapidjson![RapidJson开源库使用-LMLPHP]( "RapidJson开源库使用-LMLPHP")
https://github.com/Tencent/rapidjson
官方使用手册：RapidJSON: 首页（中文版）
2.RapidJson简介
RapidJSON特点：
（1）RapidJSON小而全：它同时支持SAX和DOM风格的API，SAX解析器只有约500行代码。
（2） RapidJSON快：它的性能可与strlen()相比，可支持SSE2/SSE4.2加速，使用模版及内联函数去降低函数调用开销。
（3）RapidJSON独立：它不依赖于BOOST等外部库，它甚至不依赖于STL。
（4）RapidJSON对内存友好：在大部分32/64位机器上，每个JSON值只占16字节(除字符串外)，它预设使用一个快速的内存分配器，令分析器可以紧凑地分配内存。
（5）RapidJSON对Unicode友好：它支持UTF-8、UTF-16、UTF-32(大端序/小端序)，并内部支持这些编码的检测、校验及转码。例如，RapidJSON可以在分析一个UTF-8文件至DOM (Document Object Model, 文件对象模型)时，把当中的JSON字符串转码至UTF-16。它也支持代理对(surrogate pair)及"\u0000"(空字符)。
每个JSON值都储存为Value类，而Document类则表示整个DOM，它存储了一个DOM 树的根Value。RapidJSON的所有公开类型及函数都在rapidjson命名空间中。
3.加载RapidJson库
在项目中只需要将 include/rapidjson 目录复制至系统或项目的 include 目录中。
4.代码示例
#include "funset.hpp"
#include "rapidjson/document.h"
// #include "rapidjson/writer.h"
#include "rapidjson/prettywriter.h"
#include "rapidjson/stringbuffer.h"
#include <iostream>
#include <fstream>
#include <string>
#include "common.hpp"
int test_rapidjson_parse()
{
#ifdef _MSC_VER
const char *file_name = "E:/GitCode/Messy_Test/testdata/json.data";
#else
const char *file_name = "testdata/json.data";
#endif
std::ifstream in(file_name);
if (!in.is_open())
{
fprintf(stderr, "fail to read json file: %s\n", file_name);
return -1;
}
std::string json_content((std::istreambuf_iterator<char>(in)), std::istreambuf_iterator<char>());
in.close();
rapidjson::Document dom;
if (!dom.Parse(json_content.c_str()).HasParseError())
{
if (dom.HasMember("name") && dom["name"].IsString())
{
fprintf(stdout, "name: %s\n", dom["name"].GetString());
}
if (dom.HasMember("address") && dom["address"].IsString())
{
fprintf(stdout, "address: %s\n", utf8_to_gbk(dom["address"].GetString()));
}
if (dom.HasMember("age") && dom["age"].IsInt())
{
fprintf(stdout, "age: %d\n", dom["age"].GetInt());
}
const char *tmp = "xxx";
if (!dom.HasMember(tmp))
{
fprintf(stdout, "Warning: it has no member: %s\n", tmp);
}
if (dom.HasMember("value1") && dom["value1"].IsArray())
{
const rapidjson::Value &arr = dom["value1"];
for (int i = 0; i < arr.Size(); ++i)
{
const rapidjson::Value &tmp = arr[i];
fprintf(stdout, "value1:\ni = %d:", i);
for (int j = 0; j < tmp.Size(); ++j)
{
if (tmp[j].IsInt())
fprintf(stdout, "%d, ", tmp[j].GetInt());
if (tmp[j].IsFloat())
fprintf(stdout, "%.1f, ", tmp[j].GetFloat());
}
fprintf(stdout, "\n");
}
}
if (dom.HasMember("value2") && dom["value2"].IsArray())
{
const rapidjson::Value &arr = dom["value2"];
fprintf(stdout, "value2: ");
for (int i = 0; i < arr.Size(); ++i)
{
fprintf(stdout, "%.2f, ", arr[i].GetFloat());
}
fprintf(stdout, "\n");
}
if (dom.HasMember("bei_jing") && dom["bei_jing"].IsObject())
{
const rapidjson::Value &obj = dom["bei_jing"];
if (obj.HasMember("address") && obj["address"].IsString())
{
fprintf(stdout, "address: %s\n", utf8_to_gbk(obj["address"].GetString()));
}
if (obj.HasMember("car") && obj["car"].IsBool())
{
fprintf(stdout, "car: %d\n", obj["car"].GetBool());
}
if (obj.HasMember("cat") && obj["cat"].IsBool())
{
fprintf(stdout, "cat: %d\n", obj["cat"].GetBool());
}
}
if (dom.HasMember("shan_dong") && dom["shan_dong"].IsObject())
{
const rapidjson::Value &obj = dom["shan_dong"];
if (obj.HasMember("address") && obj["address"].IsString())
{
fprintf(stdout, "address: %s\n", utf8_to_gbk(obj["address"].GetString()));
}
if (obj.HasMember("value1") && obj["value1"].IsArray())
{
const rapidjson::Value &arr = obj["value1"];
if (arr[0].HasMember("ji_nan") && arr[0]["ji_nan"].IsString())
{
fprintf(stdout, "ji_nan: %s\n", utf8_to_gbk(arr[0]["ji_nan"].GetString()));
}
if (arr[0].HasMember("tai_an") && arr[0]["tai_an"].IsString())
{
fprintf(stdout, "tai_an: %s\n", utf8_to_gbk(arr[0]["tai_an"].GetString()));
}
}
}
}
else
{
fprintf(stderr, "fail to parse json file: %s\n", file_name);
return -1;
}
// iter json
for (rapidjson::Value::ConstMemberIterator iter = dom.MemberBegin(); iter != dom.MemberEnd(); ++iter)
{
fprintf(stdout, "iter json name: %s, type: %d\n", iter->name.GetString(), iter->value.GetType());
}
return 0;
}
int test_rapidjson_write()
{
rapidjson::StringBuffer buf;
// rapidjson::Writer<rapidjson::StringBuffer> writer(buf);
rapidjson::PrettyWriter<rapidjson::StringBuffer> writer(buf); // it can word wrap
writer.StartObject();
writer.Key("name");
writer.String("spring");
writer.Key("address");
writer.String("北京");
writer.Key("age");
writer.Int(30);
writer.Key("value1");
writer.StartArray();
writer.StartArray();
writer.Double(23);
writer.Double(43);
writer.Double(-2.3);
writer.Double(6.7);
writer.Double(90);
writer.EndArray();
writer.StartArray();
writer.Int(-9);
writer.Int(-19);
writer.Int(10);
writer.Int(2);
writer.EndArray();
writer.StartArray();
writer.Int(-5);
writer.Int(-55);
writer.EndArray();
writer.EndArray();
writer.Key("value2");
writer.StartArray();
writer.Double(13.3);
writer.Double(1.9);
writer.Double(2.10);
writer.EndArray();
writer.Key("bei_jing");
writer.StartObject();
writer.Key("address");
writer.String("海淀");
writer.Key("car");
writer.Bool(false);
writer.Key("cat");
writer.Bool(true);
writer.EndObject();
writer.Key("shan_dong");
writer.StartObject();
writer.Key("address");
writer.String("济南");
writer.Key("value1");
writer.StartArray();
writer.Key("ji_nan");
writer.String("趵突泉");
writer.Key("tai_an");
writer.String("泰山");
writer.EndArray();
writer.EndObject();
writer.EndObject();
const char *json_content = buf.GetString();
fprintf(stdout, "json content: %s\n", json_content);
#ifdef _MSC_VER
const char *file_name = "E:/GitCode/Messy_Test/testdata/out.json";
#else
const char *file_name = "testdata/out.json";
#endif
std::ofstream outfile;
outfile.open(file_name);
if (!outfile.is_open())
{
fprintf(stderr, "fail to open file to write: %s\n", file_name);
return -1;
}
outfile << json_content << std::endl;
outfile.close();
return 0;
}json文件内容如下所示：
{
"name": "spring",
"address": "北京",
"age": 30,
"value1": [
[
23,
43,
-2.3,
6.7,
90
],
[
-9,
-19,
10,
2
],
[
-5,
-55
]
],
"value2": [
13.3,
1.9,
2.10
],
"bei_jing": {
"address": "海淀",
"car": false,
"cat": true
},
"shan_dong": {
"address": "济南",
"value1": [
{
"ji_nan": "趵突泉"
},
{
"tai_an": "泰山"
}
]
}
}