How to receive Go WebSocket messages?

The method of receiving WebSocket messages in Go depends on the client and server side: Client: Use the ReadMessage function to read the message and return the message type, payload and error. Server: Read the ReadMessage method of the connected client, which also returns the message type, payload and error.

How to receive Go WebSocket messages?

WebSocket is a full-duplex communication protocol that allows clients and servers to communicate in both directions after establishing a single connection. This article explains how to receive WebSocket messages in Go.

Client receives messages

On the client, you can receive messages through the ReadMessage function:

import "github.com/gorilla/websocket"

type Message struct {
    Type int
    Payload []byte
}

func readMessage(conn *websocket.Conn) (*Message, error) {
    mt, r, err := conn.ReadMessage()
    if err != nil {
        return nil, err
    }

    return &Message{
        Type:    mt,
        Payload: r,
    }, nil
}

ReadMessage The function returns three Values: message type (mt), message payload (r), and an error (err). The message type is an integer value indicating the type of message (text, binary, etc.).

Server receives messages

On the server side, you can receive messages through the ReadMessage method of client connection:

func (c *Client) readMessage() (*Message, error) {
    mt, r, err := c.conn.ReadMessage()
    if err != nil {
        return nil, err
    }

    return &Message{
        Type:    mt,
        Payload: r,
    }, nil
}

Practical case

The following is an example of a Go client that receives WebSocket messages and outputs them to the console:

package main

import (
    "fmt"
    "log"

    "github.com/gorilla/websocket"
)

func main() {
    conn, _, err := websocket.DefaultDialer.Dial("ws://example.com/ws", nil)
    if err != nil {
        log.Fatal("dial:", err)
    }
    defer conn.Close()

    for {
        _, message, err := conn.ReadMessage()
        if err != nil {
            if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway,
                websocket.CloseAbnormalClosure) {
                log.Fatal("unexpected close:", err)
            }
            continue
        }

        fmt.Printf("received: %s\n", message)
    }
}

Similarly, the following is an example of a Go server that receives WebSocket messages and stores them in the database:

package main

import (
    "database/sql"
    "fmt"
    "log"

    "github.com/gorilla/websocket"
)

func main() {
    // 数据库设置...

    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        log.Fatal("upgrade:", err)
    }
    defer conn.Close()

    for {
        _, message, err := conn.ReadMessage()
        if err != nil {
            if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway,
                websocket.CloseAbnormalClosure) {
                log.Fatal("unexpected close:", err)
            }
            continue
        }

        // 将消息保存到数据库...
    }
}

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