在Rust中如何将一个结构映射到另一个结构？

#[derive(Debug)]
struct StructA {
    field1: i32,
    field2: String,
}

#[derive(Debug)]
struct StructB {
    field1: i32,
    field2: String,
}

impl From<StructA> for StructB {
    fn from(a: StructA) -> Self {
        StructB {
            field1: a.field1,
            field2: a.field2,
        }
    }
}

fn main() {
    let a = StructA {
        field1: 42,
        field2: String::from("Hello"),
    };

    let b: StructB = a.into();
    println!("{:?}", b);
}