Redis原理之网络通信协议笔记

￡神魔★判官ぃ 2024-02-05 17:06 8阅读 0赞

**目录**

1. RESP协议

2. 自定义Socket连接Redis

--------------------

## 1. RESP协议 ##

![774a7b0ea3224f3c84d5d7866f7e2ab6.png][]

## ![25319447cb9b461ab6b7d43769b98330.png][] 2. 自定义Socket连接Redis ##

public class MyRedisClient {
    
        static Socket s;
        static PrintWriter writer;
        static BufferedReader reader;
    
        static Object obj;
    
        public static void main(String[] args) {
            try {
                // 1.建立连接
                String host = "xx";
                int port = 6379;
                s = new Socket(host, port);
                // 2.获取输出流、输入流
                writer = new PrintWriter(new OutputStreamWriter(s.getOutputStream(), StandardCharsets.UTF_8));
                reader = new BufferedReader(new InputStreamReader(s.getInputStream(), StandardCharsets.UTF_8));
    
                // 3.发出请求
    
    
                // 3.2.set name helloworld
                sendRequest("set", "name", "helloworld");
                // 4.解析响应
                obj = handleResponse();
                System.out.println("obj = " + obj);
    
                // 3.2.set name 虎哥
                sendRequest("get", "name");
                // 4.解析响应
                obj = handleResponse();
                System.out.println("obj = " + obj);
    
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                // 5.释放连接
                try {
                    if (reader != null) reader.close();
                    if (writer != null) writer.close();
                    if (s != null) s.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    
        private static Object handleResponse() throws IOException {
            // 读取首字节
            int prefix = reader.read();
            // 判断数据类型标示
            switch (prefix) {
                case '+': // 单行字符串，直接读一行
                    return reader.readLine();
                case '-': // 异常，也读一行
                    throw new RuntimeException(reader.readLine());
                case ':': // 数字
                    return Long.parseLong(reader.readLine());
                case '$': // 多行字符串
                    // 先读长度
                    int len = Integer.parseInt(reader.readLine());
                    if (len == -1) {
                        return null;
                    }
                    if (len == 0) {
                        return "";
                    }
                    // 再读数据,读len个字节。我们假设没有特殊字符，所以读一行（简化）
                    return reader.readLine();
                case '*':
                    return readBulkString();
                default:
                    throw new RuntimeException("错误的数据格式！");
            }
        }
    
        private static Object readBulkString() throws IOException {
            // 获取数组大小
            int len = Integer.parseInt(reader.readLine());
            if (len <= 0) {
                return null;
            }
            // 定义集合，接收多个元素
            List<Object> list = new ArrayList<>(len);
            // 遍历，依次读取每个元素
            for (int i = 0; i < len; i++) {
                list.add(handleResponse());
            }
            return list;
        }
    
        // set name 虎哥
        private static void sendRequest(String ... args) {
            writer.println("*" + args.length);
            for (String arg : args) {
                writer.println("$" + arg.getBytes(StandardCharsets.UTF_8).length);
                writer.println(arg);
            }
            writer.flush();
        }
    }

[774a7b0ea3224f3c84d5d7866f7e2ab6.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/51507eaef94d4bb99cc16b05c02145ee.png
[25319447cb9b461ab6b7d43769b98330.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/ed451d231087475a8154527f70061303.png