在Rust中生成Json
前言
周末在家,没什么事,看到之前学习Rust时,当时想生成JSON,不管那个语言,在项目中使用JSON序列化和反序列化,都是必不可少的.在Rust中使用serdejson组件.serde是Rust语言的序列化和反序列化框架,serdejson就是serde框架下json序列化和反序列话的组件.在官方文档介绍
1. 在toml文件引入serde和serdejson包
[dependencies]
# 引入serde组件
serde = { version = "1.0.192", features = ["derive"]}
# 引入serde json组件
serde_json = "1"2. 测试代码
//引入serde
use serde::{Deserialize, Serialize};
//这一点和其他语言差不多,不过是用宏Serialize指定序列化
//Deserialize宏 指定反序列化
#[derive(Serialize, Deserialize, Debug)]
struct Person
{
id: i32,
name: &'static str,
}
fn main() {
println!("Hello, world!");
//序列化 将实体序列化为json字符串
let person = Person { id: 20, name: "test string" };
let ps = serde_json::to_string(&person).unwrap(); println!("serialize json:{:?}", pt);
//反序列化 从json 字符串反序列化为实体
let pt: Person = serde_json::from_str(&ps).unwrap();
println!("deserialize person{:?}", pt);
let pp1 = Person{ id: 20, name:""};
}这样的代码,编译会不通过的.错误提示:
是因为Person中name定义的类型是有生命周期的.这里不应该用这个类型.
#[derive(Serialize, Deserialize, Debug)]
struct Person
{
id: i32,
name: String //&'static str改为String
}
let person = Person { id: 20, name: "test string".to_string() }; //"test string"改为 "test string".to_string()编译成功后,打印的效果:
serde文档上介绍说是没有反射和运行时的开销,这是因为Serialize和Deserialize在编译时在实体上实现了Serialize和Deserialize方法.这个可以通过cargo expand工具,查看生成宏
# 使用expan 将宏展开 输出到macor.rs
cargo expand > macro.rs
expand在Windows上输出到文件,在RustRover无法直接查看的,是因为在Windows上通过管道符输出到文件中,创建文件的编码格式,不是UTF-8,是UTF-16,所以想在RustRover查看该文件的话,就需要将macro.rs文件编码格式改为UTF-8.
#![feature(prelude_import)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
use serde::{Deserialize, Serialize};
struct Person {
id: i32,
name: String,
}
#[doc(hidden)]
#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
const _: () = {
#[allow(unused_extern_crates, clippy::useless_attribute)]
extern crate serde as _serde;
#[automatically_derived]
//为Person实现serialize
impl _serde::Serialize for Person {
fn serialize<__S>(
&self,
__serializer: __S,
) -> _serde::__private::Result<__S::Ok, __S::Error>
where
__S: _serde::Serializer,
{
let mut __serde_state = _serde::Serializer::serialize_struct(
__serializer,
"Person",
false as usize + 1 + 1,
)?;
_serde::ser::SerializeStruct::serialize_field(
&mut __serde_state,
"id",
&self.id,
)?;
_serde::ser::SerializeStruct::serialize_field(
&mut __serde_state,
"name",
&self.name,
)?;
_serde::ser::SerializeStruct::end(__serde_state)
}
}
};
#[doc(hidden)]
#[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
const _: () = {
#[allow(unused_extern_crates, clippy::useless_attribute)]
extern crate serde as _serde;
#[automatically_derived]
//为Person实现deserialize
impl<'de> _serde::Deserialize<'de> for Person {
fn deserialize<__D>(
__deserializer: __D,
) -> _serde::__private::Result<Self, __D::Error>
where
__D: _serde::Deserializer<'de>,
{
#[allow(non_camel_case_types)]
#[doc(hidden)]
enum __Field {
__field0,
__field1,
__ignore,
}
#[doc(hidden)]
struct __FieldVisitor;
impl<'de> _serde::de::Visitor<'de> for __FieldVisitor {
type Value = __Field;
fn expecting(
&self,
__formatter: &mut _serde::__private::Formatter,
) -> _serde::__private::fmt::Result {
_serde::__private::Formatter::write_str(
__formatter,
"field identifier",
)
}
fn visit_u64<__E>(
self,
__value: u64,
) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
0u64 => _serde::__private::Ok(__Field::__field0),
1u64 => _serde::__private::Ok(__Field::__field1),
_ => _serde::__private::Ok(__Field::__ignore),
}
}
fn visit_str<__E>(
self,
__value: &str,
) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
"id" => _serde::__private::Ok(__Field::__field0),
"name" => _serde::__private::Ok(__Field::__field1),
_ => _serde::__private::Ok(__Field::__ignore),
}
}
fn visit_bytes<__E>(
self,
__value: &[u8],
) -> _serde::__private::Result<Self::Value, __E>
where
__E: _serde::de::Error,
{
match __value {
b"id" => _serde::__private::Ok(__Field::__field0),
b"name" => _serde::__private::Ok(__Field::__field1),
_ => _serde::__private::Ok(__Field::__ignore),
}
}
}
impl<'de> _serde::Deserialize<'de> for __Field {
#[inline]
fn deserialize<__D>(
__deserializer: __D,
) -> _serde::__private::Result<Self, __D::Error>
where
__D: _serde::Deserializer<'de>,
{
_serde::Deserializer::deserialize_identifier(
__deserializer,
__FieldVisitor,
)
}
}
#[doc(hidden)]
struct __Visitor<'de> {
marker: _serde::__private::PhantomData<Person>,
lifetime: _serde::__private::PhantomData<&'de ()>,
}
impl<'de> _serde::de::Visitor<'de> for __Visitor<'de> {
type Value = Person;
fn expecting(
&self,
__formatter: &mut _serde::__private::Formatter,
) -> _serde::__private::fmt::Result {
_serde::__private::Formatter::write_str(__formatter, "struct Person")
}
#[inline]
fn visit_seq<__A>(
self,
mut __seq: __A,
) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::SeqAccess<'de>,
{
let __field0 = match _serde::de::SeqAccess::next_element::<
i32,
>(&mut __seq)? {
_serde::__private::Some(__value) => __value,
_serde::__private::None => {
return _serde::__private::Err(
_serde::de::Error::invalid_length(
0usize,
&"struct Person with 2 elements",
),
);
}
};
let __field1 = match _serde::de::SeqAccess::next_element::<
String,
>(&mut __seq)? {
_serde::__private::Some(__value) => __value,
_serde::__private::None => {
return _serde::__private::Err(
_serde::de::Error::invalid_length(
1usize,
&"struct Person with 2 elements",
),
);
}
};
_serde::__private::Ok(Person {
id: __field0,
name: __field1,
})
}
#[inline]
fn visit_map<__A>(
self,
mut __map: __A,
) -> _serde::__private::Result<Self::Value, __A::Error>
where
__A: _serde::de::MapAccess<'de>,
{
let mut __field0: _serde::__private::Option<i32> = _serde::__private::None;
let mut __field1: _serde::__private::Option<String> = _serde::__private::None;
while let _serde::__private::Some(__key) = _serde::de::MapAccess::next_key::<
__Field,
>(&mut __map)? {
match __key {
__Field::__field0 => {
if _serde::__private::Option::is_some(&__field0) {
return _serde::__private::Err(
<__A::Error as _serde::de::Error>::duplicate_field("id"),
);
}
__field0 = _serde::__private::Some(
_serde::de::MapAccess::next_value::<i32>(&mut __map)?,
);
}
__Field::__field1 => {
if _serde::__private::Option::is_some(&__field1) {
return _serde::__private::Err(
<__A::Error as _serde::de::Error>::duplicate_field("name"),
);
}
__field1 = _serde::__private::Some(
_serde::de::MapAccess::next_value::<String>(&mut __map)?,
);
}
_ => {
let _ = _serde::de::MapAccess::next_value::<
_serde::de::IgnoredAny,
>(&mut __map)?;
}
}
}
let __field0 = match __field0 {
_serde::__private::Some(__field0) => __field0,
_serde::__private::None => {
_serde::__private::de::missing_field("id")?
}
};
let __field1 = match __field1 {
_serde::__private::Some(__field1) => __field1,
_serde::__private::None => {
_serde::__private::de::missing_field("name")?
}
};
_serde::__private::Ok(Person {
id: __field0,
name: __field1,
})
}
}
#[doc(hidden)]
const FIELDS: &'static [&'static str] = &["id", "name"];
_serde::Deserializer::deserialize_struct(
__deserializer,
"Person",
FIELDS,
__Visitor {
marker: _serde::__private::PhantomData::<Person>,
lifetime: _serde::__private::PhantomData,
},
)
}
}
};
#[automatically_derived]
impl ::core::fmt::Debug for Person {
#[inline]
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
::core::fmt::Formatter::debug_struct_field2_finish(
f,
"Person",
"id",
&self.id,
"name",
&&self.name,
)
}
}
fn main() {
{
::std::io::_print(format_args!("Hello, world!\n"));
};
let person = Person {
id: 20,
name: "test string".to_string(),
};
let json = serde_json::to_string(&person).unwrap();
{
::std::io::_print(format_args!("serialize json:{0}\n", json));
};
let pt: Person = serde_json::from_str(&json).unwrap();
{
::std::io::_print(format_args!("deserialize person:{0:?}\n", pt));
};
}
秋风
2024-07-14