使用serde_json序列化具有非字符串键的映射

[dependencies]
serde = "1.0"
serde_json = "1.0"

use std::collections::HashMap;

fn main() {
    let mut map = HashMap::new();
    map.insert(1, "value1");
    map.insert(2, "value2");
    map.insert(3, "value3");
}

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct CustomMap(HashMap<i32, String>);

use serde_json;

fn main() {
    let custom_map = CustomMap(map);
    let json_string = serde_json::to_string(&custom_map).unwrap();
    println!("{}", json_string);
}

use serde_json;

fn main() {
    let json_string = r#"{"0": "value1", "1": "value2", "2": "value3"}"#;
    let custom_map: CustomMap = serde_json::from_str(json_string).unwrap();
    println!("{:?}", custom_map);
}