Rust :也谈Json与转换

Json类型是一种重要“可读”的数据类型，用到的地方很多，Rust在Json上各种处理还是很人性化，使用起来也很方便。

一、toml

[dependencies]
serde_json = "1.0.1"
serde = {version ="1.0" ,features = ["derive"]}

二、main.rs

知识点：Json创建和转化。

1、Json如何创建?
不管是创建类似python dict类型，还是从字符类型来生成，都是很方便的。

2、有类型的与Struct的转化和无类型与Value的转化。

serde_json常见方法是from_str()、from_value(),from_bytes()、from_reader()。

也就是说，可以从字符串，从文件，从字节都可以转换至特定或不特定的对象。

相关txt素材：

在src目录下，创建一个text.txt文件，试验一下Json从文件的类型转换，内容格式如下（格式不要错）：

    {
        "name": "newbi",
        "age": 43,
        "phones": [
            "021 68888888",
            "021 77788888"
        ]
    }

相关代码如下：

use serde_json::json;
use serde::{Deserialize, Serialize};
use serde_json:: Value;
use std::net::{TcpListener, TcpStream};
#[derive(Debug,Deserialize, Serialize,PartialEq)]
struct TypeRecord {
    name: String,
    age: u32,
    phones: Vec<String>,
}

#[derive(Deserialize, Debug)]
struct Client {
    name: String,
    old: i32,
}

fn main(){
    // 创建一个空的JSON对象
    // 对象类似于python中的dict
    let mut _json    = json!({});
    // 添加元素，name,age，address及对应值
    _json["name"]    = json!("newbii");//多写i
    _json["age"]     = json!(43);
    _json["address"] = json!("pudong xiangshan street");
    _json["phones"]  = json!(["021 68888888","021 77788888"]);
    _json["games"]   = json!(vec!["wukong","World War Z"]);
    // 修改值并覆盖
    _json["name"] = json!("newbi");//更正多写i
    // 删除address,games及对应值
    _json.as_object_mut().unwrap().remove("address");
    _json.as_object_mut().unwrap().remove("games");
    println!("_json:{:?}",_json);

    // json是&str类型
    let json = r#"
    {
        "name": "newbi",
        "age": 43,
        "phones": [
            "021 68888888",
            "021 77788888"
        ]
    }"#;
    let json_value = json!({
        "name": "newbi",
        "age": 43,
        "phones": [
            "021 68888888",
            "021 77788888"
        ]
    });
    assert_eq!(json_value,_json);
    // 在字符的引号前加"\"
    let bytes = b"
    {
        \"name\": \"newbi\",
        \"age\": 43,
        \"phones\": [
            \"021 68888888\",
            \"021 77788888\"
        ]
    }";

    //json的目的解析为特定的struct
    let record_1: TypeRecord = serde_json::from_str(json).unwrap();
    let record_2: TypeRecord  = serde_json::from_value(json_value.clone()).unwrap();
    println!("json_value: {:?}",json_value);
    println!("record1   : {:?}", record_1);
    println!("record2   : {:?}", record_2);
    let record_3: TypeRecord = serde_json::from_slice(bytes).unwrap();
    println!("record3   : {:?}", record_3);
    let record_4: TypeRecord = json_from_reader_path();
    println!("record4   : {:?}", record_4);
    let record_5 : TypeRecord = json_from_reader_file();
    println!("record5   : {:?}", record_5);
    assert_eq!(record_4, record_5);
    let record_6 :TypeRecord= json_from_reader_file2();
    println!("record6   : {:?}",record_6);
    // 比较一下从json到string 
    let str_record = serde_json::to_string(&record_3).unwrap();
    println!("str_record: {:?}",str_record);
    
    // json的目的不解析为特定的struct，转化为通用的Value类型
    let _str = r#"{"name":"我就是我，不一样的烟火！","address":"四海为家"}"#;

    let none_type_value :Value = serde_json::from_str(_str).unwrap();
    println!("none_type_value: {:?}",none_type_value);
    
}

fn json_from_reader_path()->TypeRecord {
    use std::fs::File;
    use std::io::BufReader;
    
    let file = File::open("test.txt").unwrap();
    let reader = BufReader::new(file);
    let record:TypeRecord = serde_json::from_reader(reader).unwrap();
    println!("{:?}", record);
    record
}
fn json_from_reader_file()->TypeRecord {
    let content = std::fs::read_to_string("test.txt").unwrap();
    let record: TypeRecord = serde_json::from_str(&content).unwrap();
    record
}
fn json_from_reader_file2()->TypeRecord {
    let content = include_str!("test.txt");
    let record: TypeRecord = serde_json::from_str(content).unwrap();
    record
}
fn json_from_reader_stream(tcp_stream:TcpStream) {
    let mut de = serde_json::Deserializer::from_reader(tcp_stream);
    let _u = Client::deserialize(&mut de).unwrap();
}

上面代码还可以看到，TcpStream也可以通过Json转化为特定类型。

serde_json::Deserializer::from_reader(tcp_stream);

三、输出

    Finished `release` profile [optimized] target(s) in 12.08s
     Running `D:\my_program\test_rust\target\release\test_rust.exe`
_json:Object {"age": Number(43), "name": String("newbi"), "phones": Array [String("021 68888888"), String("021 77788888")]}
json_value: Object {"age": Number(43), "name": String("newbi"), "phones": Array [String("021 68888888"), String("021 77788888")]}
record1   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record2   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record3   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
g("021 77788888")]}
record1   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record2   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record3   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record2   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record3   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record3   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record4   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record5   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
record6   : TypeRecord { name: "newbi", age: 43, phones: ["021 68888888", "021 77788888"] }
str_record: "{\"name\":\"newbi\",\"age\":43,\"phones\":[\"021 68888888\",\"021 77788888\"]}"
none_type_value: Object {"address": String("四海为家"), "name": String("我就是我，不一样的烟火！")}