最近迷上了买相机，大疆Pocket、Insta Go3、大疆Mini3、佳能50D、vivo徕卡人像大师（狗头），在买配件的时候，发现1/4螺口简直是神中之神，这个万能接口让我想到计算机设计中的接口，遂有此篇——

接口的代码格式因编程语言而异，下面提供两个经典接口的示例，分别是 REST API 和 gRPC，并对比它们的区别。

1. REST API 示例（Python Flask）
   REST API 使用 HTTP 协议，通过不同的 HTTP 方法（GET、POST、PUT、DELETE）操作资源，返回 JSON 或 XML 格式的数据。

from flask import Flask, jsonify, request

app = Flask(__name__)

# 模拟数据
books = [
    {"id": 1, "title": "Python Crash Course", "author": "Eric Matthes"},
    {"id": 2, "title": "Clean Code", "author": "Robert C. Martin"}
]

# 获取所有书籍
@app.route('/api/books', methods=['GET'])
def get_books():
    return jsonify(books)

# 获取单个书籍
@app.route('/api/books/<int:book_id>', methods=['GET'])
def get_book(book_id):
    book = next((b for b in books if b['id'] == book_id), None)
    if book is None:
        return jsonify({"error": "Book not found"}), 404
    return jsonify(book)

# 添加书籍
@app.route('/api/books', methods=['POST'])
def add_book():
    data = request.get_json()
    new_book = {
        "id": len(books) + 1,
        "title": data.get('title'),
        "author": data.get('author')
    }
    books.append(new_book)
    return jsonify(new_book), 201

if __name__ == '__main__':
    app.run(debug=True)

2. gRPC 示例（Python + Protocol Buffers）
   gRPC 使用 Protocol Buffers 定义服务和消息格式，通过 HTTP/2 进行通信，提供强类型接口和高性能。
   首先定义 .proto 文件（book.proto）：

syntax = "proto3";

package book;

// 定义消息格式
message Book {
    int32 id = 1;
    string title = 2;
    string author = 3;
}

message BookRequest {
    int32 id = 1;
}

message BookList {
    repeated Book books = 1;
}

// 定义服务接口
service BookService {
    // 获取所有书籍
    rpc GetBooks(google.protobuf.Empty) returns (BookList);
    
    // 获取单个书籍
    rpc GetBook(BookRequest) returns (Book);
    
    // 添加书籍
    rpc AddBook(Book) returns (Book);
}

然后实现服务端（server.py）：

import grpc
from concurrent import futures
import book_pb2
import book_pb2_grpc

class BookService(book_pb2_grpc.BookServiceServicer):
    def __init__(self):
        self.books = [
            book_pb2.Book(id=1, title="Python Crash Course", author="Eric Matthes"),
            book_pb2.Book(id=2, title="Clean Code", author="Robert C. Martin")
        ]

    def GetBooks(self, request, context):
        return book_pb2.BookList(books=self.books)

    def GetBook(self, request, context):
        for book in self.books:
            if book.id == request.id:
                return book
        context.set_code(grpc.StatusCode.NOT_FOUND)
        return book_pb2.Book()

    def AddBook(self, request, context):
        new_book = book_pb2.Book(
            id=len(self.books) + 1,
            title=request.title,
            author=request.author
        )
        self.books.append(new_book)
        return new_book

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    book_pb2_grpc.add_BookServiceServicer_to_server(BookService(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    print("Server started, listening on port 50051")
    server.wait_for_termination()

if __name__ == '__main__':
    serve()

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