前言
随便写写,自己经常用到;官方教程比我详细.
安装
sudo apt-get install rapidjson-dev
这个库完全是通过头文件实现的,直接拷贝到头文件的文件夹 also can do it.
流
内存流
输入
StringStream
#include
#include
using namespace std;
int main(int, char **)
{
const char *json = "{\"hello\" : \"ligoudan\"}";
rapidjson::StringStream input(json);
rapidjson::Document document;
document.ParseStream(input);
cout << document["hello"].GetString() << endl;
return 0;
}
输出
StringBuffer
#include
#include
#include
#include
using namespace std;
int main(int, char **)
{
rapidjson::Document document;
rapidjson::Document::AllocatorType &allocator = document.GetAllocator();
document.SetObject();
rapidjson::Value name;
name.SetString("misaka");
document.AddMember("name", name, allocator);
// output
rapidjson::StringBuffer SB;
rapidjson::Writer writer(SB);
document.Accept(writer);
cout << SB.GetString() << endl;
return 0;
}
文件流
输入
文件
{
"hello": "world",
"t": true,
"f": false,
"n": null,
"i": 123,
"pi": 3.1416,
"a": [1, 2, 3, 4]
}
呆马
#include
#include
#include
#include
using namespace std;
int main(int, char **)
{
FILE *fp = fopen("input.json", "r"); // stupid windows need rb
char buf[0XFFFF];
//FileReadStream(FILE *fp, char *buffer, std::size_t bufferSize)
rapidjson::FileReadStream input(fp, buf, sizeof(buf));
rapidjson::Document document;
document.ParseStream(input);
fclose(fp);
cout << boolalpha;
cout << document["hello"].GetString() << endl;
cout << document["t"].GetBool() << endl;
cout << (document["n"].IsNull() ? "null" : "He He") << endl;
cout << document["pi"].GetDouble() << endl;
return 0;
}
输出
格式有点小问题
#include
#include
#include
#include
using namespace std;
int main(int, char **)
{
rapidjson::Document document;
rapidjson::Document::AllocatorType &allocator = document.GetAllocator();
document.SetObject();
rapidjson::Value hello;
hello.SetString("world");
rapidjson::Value t;
t.SetBool(true);
rapidjson::Value f(false);
rapidjson::Value n;
n.SetNull();
rapidjson::Value i(123);
rapidjson::Value pi(3.1416);
rapidjson::Value a;
a.SetArray();
for (int i = 0; i < 4; ++i) {
a.PushBack(i+1, allocator);
}
document.AddMember("hello", hello, allocator);
document.AddMember("t", t, allocator);
document.AddMember("f", f, allocator);
document.AddMember("n", n, allocator);
document.AddMember("i", i, allocator);
document.AddMember("pi", pi, allocator);
document.AddMember("a", a, allocator);
//output
FILE *fp = fopen("output.json", "w"); // stupid win need wb
char buf[0XFFFF];
// FileWriteStream(FILE *fp, char *buffer, std::size_t bufferSize)
rapidjson::FileWriteStream output(fp, buf, sizeof (buf));
rapidjson::Writer writer(output);
document.Accept(writer);
fclose(fp);
return 0;
}
常用操作(抄一遍教程)
#include
#include
#include
#include
// #define NDEBUG
#include
void for_each_json(const rapidjson::Document &document);
using namespace std;
int main(int, char **)
{
cout << boolalpha;
rapidjson::Document document;
rapidjson::Document::AllocatorType &allocator = document.GetAllocator();
document.SetObject();
assert(document.IsObject());
// 查找有没有name
cout << "name=" <<
(document.HasMember("name") ? document["name"].GetString() : "没有")
<< endl;
// fill
rapidjson::Value hello("world");
rapidjson::Value t(true);
rapidjson::Value f(false);
rapidjson::Value n;
n.SetNull();
rapidjson::Value i(123);
rapidjson::Value pi(3.1416);
// 暂时先不fill array 因为不会...
rapidjson::Value a;
a.SetArray();
// add member
// NOTE rapidjson为了性能,AddMember执行之后会让Value变成null
document.AddMember("hello", hello, allocator);
document.AddMember("t", t, allocator);
document.AddMember("f", f, allocator);
document.AddMember("i", i, allocator);
document.AddMember("n", n, allocator);
document.AddMember("pi", pi, allocator);
document.AddMember("a", a, allocator);
// try
assert(document["hello"].IsString());
assert(document["t"].IsBool());
assert(document["n"].IsNull());
assert(document["i"].IsInt());
assert(document["i"].IsNumber());
assert(document["pi"].IsDouble());
assert(document["a"].IsArray());
// get
cout << document["hello"].GetString() << endl;
cout << document["t"].GetBool() << endl;
cout << document["f"].GetBool() << endl;
cout << (document["n"].IsNull() ? "null" : "SB") << endl;
cout << document["i"].GetInt() << endl;
cout << document["pi"].GetDouble() << endl;
cout << "-*-*-*-*-*-华丽的分割线-*-*-*-*-*-" << endl;
// fill array
rapidjson::Value &array = document["a"]; // 因为a已经变成废铁了
/**
* 关于Array的基本操作
* Clear();
* Value & PushBack(Value &, Allocator &);
* template GenericValue & PushBack(T, Allocator &);
* Value & PopBack();
* ValueIterator Erase(ConstValueIterator pos);
* ValueIterator Erase(ConstValueIterator first, ConstValueIterator last);
*/
for (int i = 0; i < 4; ++i) {
array.PushBack(i, allocator);
}
// for each array
/*
关于Array
索引类型 : SizeType
数组size : a.Size();
*/
for(rapidjson::SizeType index = 0; index < array.Size(); ++index) {
cout << "a[" << index << "] = " << array[index].GetInt() << endl;
}
// by iterator
for (rapidjson::Value::ConstValueIterator it = array.Begin();
it != array.End(); ++it) {
cout << it->GetInt() << ' ';
} cout << endl;
// for each json
for_each_json(document);
rapidjson::StringBuffer SB;
rapidjson::Writer writer(SB);
document.Accept(writer);
cout << SB.GetString() << endl;
return 0;
}
void for_each_json(const rapidjson::Document &document)
{
rapidjson::Value::ConstMemberIterator it;
for (it = document.MemberBegin();
it != document.MemberEnd(); ++it) {
cout << it->name.GetString() << ": ";
if (it->value.IsNull()) {
cout << "null";
}
else if (it->value.IsString()) {
cout << it->value.GetString();
cout << "\tStringLength = " << it->value.GetStringLength();
}
else if (it->value.IsBool()) {
cout << it->value.GetBool();
}
else if (it->value.IsInt()) {
cout << it->value.GetInt();
}
else if (it->value.IsDouble()) {
cout << it->value.GetDouble();
}
else if (it->value.IsArray()) { // 默认Int数组
rapidjson::Value::ConstValueIterator val_it
= it->value.Begin();
for (; val_it != it->value.End(); ++val_it) {
cout << val_it->GetInt() << ' ';
}
}
else if (it->value.IsObject()) {
;
}
else {
;
}
cout << endl;
}
}
Python json模块(很抱(qian)歉(zou),我是宇宙术)
使用Python内置的json模块
test.json
{
"hello": "world",
"t": true,
"f": false,
"n": null,
"i": 123,
"pi": 3.1416,
"a": [1, 2, 3, 4]
}
#!/usr/bin/python3
import json
if __name__ == '__main__':
json_str = '''
{
"hello": "world",
"t": true,
"f": false,
"n": null,
"i": 123,
"pi": 3.1416,
"a": [1, 2, 3, 4]
}
'''
# memory stream input
data = json.loads(json_str)
print(data)
# memory stream output
out_string = json.dumps(data, ensure_ascii=False, indent=2)
print(out_string)
# file stream input
with open('test.json', 'r', encoding='utf-8') as input:
data = json.load(input, encoding='utf-8')
print(data)
# file stream output
with open('output.json', 'w', encoding='utf-8') as output:
json.dump(data, output, ensure_ascii=False, indent=4)
print('Done')
ujson版本(没什么变化)
#!/usr/bin/python3
import ujson
import json
"""
ujson
dump dumps
load loads
encode decode
"""
if __name__ == '__main__':
json_str = '''
{
"name": "misaka",
"age":14,
"school": null
}
'''
data = ujson.loads(json_str)
print(data)
with open('test.json', 'r', encoding='utf-8') as input:
data = ujson.load(input)
print(data)
# ensure_ascii=False 输出的是utf-8
result_str = ujson.dumps(data, indent=4, ensure_ascii=False)
print(result_str)
with open('output.json', 'w', encoding='utf-8') as output:
ujson.dump(data, output, indent=4, ensure_ascii=False)
print('Done')