1. 环境

• OS：macOS 11.6.8
• Rust：rustc 1.63.0 (4b91a6ea7 2022-08-08)
• Protobuf：libprotoc 3.21.5

2. 创建测试项目

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cargo new testpb
cd testpb/
cargo new snazzy --lib

在 snazzy/Cargo.toml 中添加：

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[dependencies]
bytes = "1.2.1"
prost = "0.11.0"

[build-dependencies]
prost-build = "0.11.1"

prost-build 的文档在：https://docs.rs/prost-build/0.11.1/prost_build/。

创建 snazzy/build.rs：

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fn main() {
    let mut config = prost_build::Config::new();
    config
        .out_dir("src")
        .compile_protos(&["src/items.proto"], &["."])
        .unwrap();
}

创建 snazzy/src/items.proto：

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syntax = "proto3";

package snazzy.items;

// A snazzy new shirt!
message Shirt {
  enum Size {
    SMALL = 0;
    MEDIUM = 1;
    LARGE = 2;
  }

  string color = 1;
  Size size = 2;
}

修改 snazzy/src/lib.rs：

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use std::io::Cursor;

use prost::Message;

// Include the `items` module, which is generated from items.proto.
pub mod items {
    include!("snazzy.items.rs");
}

pub fn create_large_shirt(color: String) -> items::Shirt {
    let mut shirt = items::Shirt::default();
    shirt.color = color;
    shirt.set_size(items::shirt::Size::Large);
    shirt
}

pub fn serialize_shirt(shirt: &items::Shirt) -> Vec<u8> {
    let mut buf = Vec::new();
    buf.reserve(shirt.encoded_len());
    // Unwrap is safe, since we have reserved sufficient capacity in the vector.
    shirt.encode(&mut buf).unwrap();
    buf
}

pub fn deserialize_shirt(buf: &Vec<u8>) -> Result<items::Shirt, prost::DecodeError> {
    items::Shirt::decode(&mut Cursor::new(buf))
}

在 Cargo.toml 中添加：

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[dependencies]
snazzy = { path = "snazzy" }

修改 src/main.rs：

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fn main() {
    let shirt = snazzy::create_large_shirt("White".to_string());
    println!("{:?}", shirt);
    let bytes: Vec<u8> = snazzy::serialize_shirt(&shirt);
    println!("{:?}", bytes);
    let shirt = snazzy::deserialize_shirt(&bytes);
    println!("{:?}", shirt);
}

执行：

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cargo run

输出：

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Shirt { color: "White", size: Large }
[10, 5, 87, 104, 105, 116, 101, 16, 2]
Ok(Shirt { color: "White", size: Large })